# Crypto



> Stability: 2 - Stable



The `node:crypto` module provides cryptographic functionality that includes a
set of wrappers for OpenSSL's hash, HMAC, cipher, decipher, sign, and verify
functions.

```mjs
const { createHmac } = await import('node:crypto');

const secret = 'abcdefg';
const hash = createHmac('sha256', secret)
               .update('I love cupcakes')
               .digest('hex');
console.log(hash);
// Prints:
//   c0fa1bc00531bd78ef38c628449c5102aeabd49b5dc3a2a516ea6ea959d6658e
```

```cjs
const { createHmac } = require('node:crypto');

const secret = 'abcdefg';
const hash = createHmac('sha256', secret)
               .update('I love cupcakes')
               .digest('hex');
console.log(hash);
// Prints:
//   c0fa1bc00531bd78ef38c628449c5102aeabd49b5dc3a2a516ea6ea959d6658e
```

## Determining if crypto support is unavailable

It is possible for Node.js to be built without including support for the
`node:crypto` module. In such cases, attempting to `import` from `crypto` or
calling `require('node:crypto')` will result in an error being thrown.

When using CommonJS, the error thrown can be caught using try/catch:



```cjs
let crypto;
try {
  crypto = require('node:crypto');
} catch (err) {
  console.error('crypto support is disabled!');
}
```

When using the lexical ESM `import` keyword, the error can only be
caught if a handler for `process.on('uncaughtException')` is registered
_before_ any attempt to load the module is made (using, for instance,
a preload module).

When using ESM, if there is a chance that the code may be run on a build
of Node.js where crypto support is not enabled, consider using the
[`import()`][] function instead of the lexical `import` keyword:

```mjs
let crypto;
try {
  crypto = await import('node:crypto');
} catch (err) {
  console.error('crypto support is disabled!');
}
```

## Class: `Certificate`



SPKAC is a Certificate Signing Request mechanism originally implemented by
Netscape and was specified formally as part of HTML5's `keygen` element.

`<keygen>` is deprecated since [HTML 5.2][] and new projects
should not use this element anymore.

The `node:crypto` module provides the `Certificate` class for working with SPKAC
data. The most common usage is handling output generated by the HTML5
`<keygen>` element. Node.js uses [OpenSSL's SPKAC implementation][] internally.

### Static method: `Certificate.exportChallenge(spkac[, encoding])`



* `spkac` {string|ArrayBuffer|Buffer|TypedArray|DataView}
* `encoding` {string} The [encoding][] of the `spkac` string.
* Returns: {Buffer} The challenge component of the `spkac` data structure, which
  includes a public key and a challenge.

```mjs
const { Certificate } = await import('node:crypto');
const spkac = getSpkacSomehow();
const challenge = Certificate.exportChallenge(spkac);
console.log(challenge.toString('utf8'));
// Prints: the challenge as a UTF8 string
```

```cjs
const { Certificate } = require('node:crypto');
const spkac = getSpkacSomehow();
const challenge = Certificate.exportChallenge(spkac);
console.log(challenge.toString('utf8'));
// Prints: the challenge as a UTF8 string
```

### Static method: `Certificate.exportPublicKey(spkac[, encoding])`



* `spkac` {string|ArrayBuffer|Buffer|TypedArray|DataView}
* `encoding` {string} The [encoding][] of the `spkac` string.
* Returns: {Buffer} The public key component of the `spkac` data structure,
  which includes a public key and a challenge.

```mjs
const { Certificate } = await import('node:crypto');
const spkac = getSpkacSomehow();
const publicKey = Certificate.exportPublicKey(spkac);
console.log(publicKey);
// Prints: the public key as <Buffer ...>
```

```cjs
const { Certificate } = require('node:crypto');
const spkac = getSpkacSomehow();
const publicKey = Certificate.exportPublicKey(spkac);
console.log(publicKey);
// Prints: the public key as <Buffer ...>
```

### Static method: `Certificate.verifySpkac(spkac[, encoding])`



* `spkac` {string|ArrayBuffer|Buffer|TypedArray|DataView}
* `encoding` {string} The [encoding][] of the `spkac` string.
* Returns: {boolean} `true` if the given `spkac` data structure is valid,
  `false` otherwise.

```mjs
import { Buffer } from 'node:buffer';
const { Certificate } = await import('node:crypto');

const spkac = getSpkacSomehow();
console.log(Certificate.verifySpkac(Buffer.from(spkac)));
// Prints: true or false
```

```cjs
const { Buffer } = require('node:buffer');
const { Certificate } = require('node:crypto');

const spkac = getSpkacSomehow();
console.log(Certificate.verifySpkac(Buffer.from(spkac)));
// Prints: true or false
```

### Legacy API

> Stability: 0 - Deprecated

As a legacy interface, it is possible to create new instances of
the `crypto.Certificate` class as illustrated in the examples below.

#### `new crypto.Certificate()`

Instances of the `Certificate` class can be created using the `new` keyword
or by calling `crypto.Certificate()` as a function:

```mjs
const { Certificate } = await import('node:crypto');

const cert1 = new Certificate();
const cert2 = Certificate();
```

```cjs
const { Certificate } = require('node:crypto');

const cert1 = new Certificate();
const cert2 = Certificate();
```

#### `certificate.exportChallenge(spkac[, encoding])`



* `spkac` {string|ArrayBuffer|Buffer|TypedArray|DataView}
* `encoding` {string} The [encoding][] of the `spkac` string.
* Returns: {Buffer} The challenge component of the `spkac` data structure, which
  includes a public key and a challenge.

```mjs
const { Certificate } = await import('node:crypto');
const cert = Certificate();
const spkac = getSpkacSomehow();
const challenge = cert.exportChallenge(spkac);
console.log(challenge.toString('utf8'));
// Prints: the challenge as a UTF8 string
```

```cjs
const { Certificate } = require('node:crypto');
const cert = Certificate();
const spkac = getSpkacSomehow();
const challenge = cert.exportChallenge(spkac);
console.log(challenge.toString('utf8'));
// Prints: the challenge as a UTF8 string
```

#### `certificate.exportPublicKey(spkac[, encoding])`



* `spkac` {string|ArrayBuffer|Buffer|TypedArray|DataView}
* `encoding` {string} The [encoding][] of the `spkac` string.
* Returns: {Buffer} The public key component of the `spkac` data structure,
  which includes a public key and a challenge.

```mjs
const { Certificate } = await import('node:crypto');
const cert = Certificate();
const spkac = getSpkacSomehow();
const publicKey = cert.exportPublicKey(spkac);
console.log(publicKey);
// Prints: the public key as <Buffer ...>
```

```cjs
const { Certificate } = require('node:crypto');
const cert = Certificate();
const spkac = getSpkacSomehow();
const publicKey = cert.exportPublicKey(spkac);
console.log(publicKey);
// Prints: the public key as <Buffer ...>
```

#### `certificate.verifySpkac(spkac[, encoding])`



* `spkac` {string|ArrayBuffer|Buffer|TypedArray|DataView}
* `encoding` {string} The [encoding][] of the `spkac` string.
* Returns: {boolean} `true` if the given `spkac` data structure is valid,
  `false` otherwise.

```mjs
import { Buffer } from 'node:buffer';
const { Certificate } = await import('node:crypto');

const cert = Certificate();
const spkac = getSpkacSomehow();
console.log(cert.verifySpkac(Buffer.from(spkac)));
// Prints: true or false
```

```cjs
const { Buffer } = require('node:buffer');
const { Certificate } = require('node:crypto');

const cert = Certificate();
const spkac = getSpkacSomehow();
console.log(cert.verifySpkac(Buffer.from(spkac)));
// Prints: true or false
```

## Class: `Cipher`



* Extends: {stream.Transform}

Instances of the `Cipher` class are used to encrypt data. The class can be
used in one of two ways:

* As a [stream][] that is both readable and writable, where plain unencrypted
  data is written to produce encrypted data on the readable side, or
* Using the [`cipher.update()`][] and [`cipher.final()`][] methods to produce
  the encrypted data.

The [`crypto.createCipher()`][] or [`crypto.createCipheriv()`][] methods are
used to create `Cipher` instances. `Cipher` objects are not to be created
directly using the `new` keyword.

Example: Using `Cipher` objects as streams:

```mjs
const {
  scrypt,
  randomFill,
  createCipheriv,
} = await import('node:crypto');

const algorithm = 'aes-192-cbc';
const password = 'Password used to generate key';

// First, we'll generate the key. The key length is dependent on the algorithm.
// In this case for aes192, it is 24 bytes (192 bits).
scrypt(password, 'salt', 24, (err, key) => {
  if (err) throw err;
  // Then, we'll generate a random initialization vector
  randomFill(new Uint8Array(16), (err, iv) => {
    if (err) throw err;

    // Once we have the key and iv, we can create and use the cipher...
    const cipher = createCipheriv(algorithm, key, iv);

    let encrypted = '';
    cipher.setEncoding('hex');

    cipher.on('data', (chunk) => encrypted += chunk);
    cipher.on('end', () => console.log(encrypted));

    cipher.write('some clear text data');
    cipher.end();
  });
});
```

```cjs
const {
  scrypt,
  randomFill,
  createCipheriv,
} = require('node:crypto');

const algorithm = 'aes-192-cbc';
const password = 'Password used to generate key';

// First, we'll generate the key. The key length is dependent on the algorithm.
// In this case for aes192, it is 24 bytes (192 bits).
scrypt(password, 'salt', 24, (err, key) => {
  if (err) throw err;
  // Then, we'll generate a random initialization vector
  randomFill(new Uint8Array(16), (err, iv) => {
    if (err) throw err;

    // Once we have the key and iv, we can create and use the cipher...
    const cipher = createCipheriv(algorithm, key, iv);

    let encrypted = '';
    cipher.setEncoding('hex');

    cipher.on('data', (chunk) => encrypted += chunk);
    cipher.on('end', () => console.log(encrypted));

    cipher.write('some clear text data');
    cipher.end();
  });
});
```

Example: Using `Cipher` and piped streams:

```mjs
import {
  createReadStream,
  createWriteStream,
} from 'node:fs';

import {
  pipeline,
} from 'node:stream';

const {
  scrypt,
  randomFill,
  createCipheriv,
} = await import('node:crypto');

const algorithm = 'aes-192-cbc';
const password = 'Password used to generate key';

// First, we'll generate the key. The key length is dependent on the algorithm.
// In this case for aes192, it is 24 bytes (192 bits).
scrypt(password, 'salt', 24, (err, key) => {
  if (err) throw err;
  // Then, we'll generate a random initialization vector
  randomFill(new Uint8Array(16), (err, iv) => {
    if (err) throw err;

    const cipher = createCipheriv(algorithm, key, iv);

    const input = createReadStream('test.js');
    const output = createWriteStream('test.enc');

    pipeline(input, cipher, output, (err) => {
      if (err) throw err;
    });
  });
});
```

```cjs
const {
  createReadStream,
  createWriteStream,
} = require('node:fs');

const {
  pipeline,
} = require('node:stream');

const {
  scrypt,
  randomFill,
  createCipheriv,
} = require('node:crypto');

const algorithm = 'aes-192-cbc';
const password = 'Password used to generate key';

// First, we'll generate the key. The key length is dependent on the algorithm.
// In this case for aes192, it is 24 bytes (192 bits).
scrypt(password, 'salt', 24, (err, key) => {
  if (err) throw err;
  // Then, we'll generate a random initialization vector
  randomFill(new Uint8Array(16), (err, iv) => {
    if (err) throw err;

    const cipher = createCipheriv(algorithm, key, iv);

    const input = createReadStream('test.js');
    const output = createWriteStream('test.enc');

    pipeline(input, cipher, output, (err) => {
      if (err) throw err;
    });
  });
});
```

Example: Using the [`cipher.update()`][] and [`cipher.final()`][] methods:

```mjs
const {
  scrypt,
  randomFill,
  createCipheriv,
} = await import('node:crypto');

const algorithm = 'aes-192-cbc';
const password = 'Password used to generate key';

// First, we'll generate the key. The key length is dependent on the algorithm.
// In this case for aes192, it is 24 bytes (192 bits).
scrypt(password, 'salt', 24, (err, key) => {
  if (err) throw err;
  // Then, we'll generate a random initialization vector
  randomFill(new Uint8Array(16), (err, iv) => {
    if (err) throw err;

    const cipher = createCipheriv(algorithm, key, iv);

    let encrypted = cipher.update('some clear text data', 'utf8', 'hex');
    encrypted += cipher.final('hex');
    console.log(encrypted);
  });
});
```

```cjs
const {
  scrypt,
  randomFill,
  createCipheriv,
} = require('node:crypto');

const algorithm = 'aes-192-cbc';
const password = 'Password used to generate key';

// First, we'll generate the key. The key length is dependent on the algorithm.
// In this case for aes192, it is 24 bytes (192 bits).
scrypt(password, 'salt', 24, (err, key) => {
  if (err) throw err;
  // Then, we'll generate a random initialization vector
  randomFill(new Uint8Array(16), (err, iv) => {
    if (err) throw err;

    const cipher = createCipheriv(algorithm, key, iv);

    let encrypted = cipher.update('some clear text data', 'utf8', 'hex');
    encrypted += cipher.final('hex');
    console.log(encrypted);
  });
});
```

### `cipher.final([outputEncoding])`



* `outputEncoding` {string} The [encoding][] of the return value.
* Returns: {Buffer | string} Any remaining enciphered contents.
  If `outputEncoding` is specified, a string is
  returned. If an `outputEncoding` is not provided, a [`Buffer`][] is returned.

Once the `cipher.final()` method has been called, the `Cipher` object can no
longer be used to encrypt data. Attempts to call `cipher.final()` more than
once will result in an error being thrown.

### `cipher.getAuthTag()`



* Returns: {Buffer} When using an authenticated encryption mode (`GCM`, `CCM`,
  `OCB`, and `chacha20-poly1305` are currently supported), the
  `cipher.getAuthTag()` method returns a
  [`Buffer`][] containing the _authentication tag_ that has been computed from
  the given data.

The `cipher.getAuthTag()` method should only be called after encryption has
been completed using the [`cipher.final()`][] method.

If the `authTagLength` option was set during the `cipher` instance's creation,
this function will return exactly `authTagLength` bytes.

### `cipher.setAAD(buffer[, options])`



* `buffer` {string|ArrayBuffer|Buffer|TypedArray|DataView}
* `options` {Object} [`stream.transform` options][]
  * `plaintextLength` {number}
  * `encoding` {string} The string encoding to use when `buffer` is a string.
* Returns: {Cipher} for method chaining.

When using an authenticated encryption mode (`GCM`, `CCM`, `OCB`, and
`chacha20-poly1305` are
currently supported), the `cipher.setAAD()` method sets the value used for the
_additional authenticated data_ (AAD) input parameter.

The `plaintextLength` option is optional for `GCM` and `OCB`. When using `CCM`,
the `plaintextLength` option must be specified and its value must match the
length of the plaintext in bytes. See [CCM mode][].

The `cipher.setAAD()` method must be called before [`cipher.update()`][].

### `cipher.setAutoPadding([autoPadding])`



* `autoPadding` {boolean} **Default:** `true`
* Returns: {Cipher} for method chaining.

When using block encryption algorithms, the `Cipher` class will automatically
add padding to the input data to the appropriate block size. To disable the
default padding call `cipher.setAutoPadding(false)`.

When `autoPadding` is `false`, the length of the entire input data must be a
multiple of the cipher's block size or [`cipher.final()`][] will throw an error.
Disabling automatic padding is useful for non-standard padding, for instance
using `0x0` instead of PKCS padding.

The `cipher.setAutoPadding()` method must be called before
[`cipher.final()`][].

### `cipher.update(data[, inputEncoding][, outputEncoding])`



* `data` {string|Buffer|TypedArray|DataView}
* `inputEncoding` {string} The [encoding][] of the data.
* `outputEncoding` {string} The [encoding][] of the return value.
* Returns: {Buffer | string}

Updates the cipher with `data`. If the `inputEncoding` argument is given,
the `data`
argument is a string using the specified encoding. If the `inputEncoding`
argument is not given, `data` must be a [`Buffer`][], `TypedArray`, or
`DataView`. If `data` is a [`Buffer`][], `TypedArray`, or `DataView`, then
`inputEncoding` is ignored.

The `outputEncoding` specifies the output format of the enciphered
data. If the `outputEncoding`
is specified, a string using the specified encoding is returned. If no
`outputEncoding` is provided, a [`Buffer`][] is returned.

The `cipher.update()` method can be called multiple times with new data until
[`cipher.final()`][] is called. Calling `cipher.update()` after
[`cipher.final()`][] will result in an error being thrown.

## Class: `Decipher`



* Extends: {stream.Transform}

Instances of the `Decipher` class are used to decrypt data. The class can be
used in one of two ways:

* As a [stream][] that is both readable and writable, where plain encrypted
  data is written to produce unencrypted data on the readable side, or
* Using the [`decipher.update()`][] and [`decipher.final()`][] methods to
  produce the unencrypted data.

The [`crypto.createDecipher()`][] or [`crypto.createDecipheriv()`][] methods are
used to create `Decipher` instances. `Decipher` objects are not to be created
directly using the `new` keyword.

Example: Using `Decipher` objects as streams:

```mjs
import { Buffer } from 'node:buffer';
const {
  scryptSync,
  createDecipheriv,
} = await import('node:crypto');

const algorithm = 'aes-192-cbc';
const password = 'Password used to generate key';
// Key length is dependent on the algorithm. In this case for aes192, it is
// 24 bytes (192 bits).
// Use the async `crypto.scrypt()` instead.
const key = scryptSync(password, 'salt', 24);
// The IV is usually passed along with the ciphertext.
const iv = Buffer.alloc(16, 0); // Initialization vector.

const decipher = createDecipheriv(algorithm, key, iv);

let decrypted = '';
decipher.on('readable', () => {
  let chunk;
  while (null !== (chunk = decipher.read())) {
    decrypted += chunk.toString('utf8');
  }
});
decipher.on('end', () => {
  console.log(decrypted);
  // Prints: some clear text data
});

// Encrypted with same algorithm, key and iv.
const encrypted =
  'e5f79c5915c02171eec6b212d5520d44480993d7d622a7c4c2da32f6efda0ffa';
decipher.write(encrypted, 'hex');
decipher.end();
```

```cjs
const {
  scryptSync,
  createDecipheriv,
} = require('node:crypto');
const { Buffer } = require('node:buffer');

const algorithm = 'aes-192-cbc';
const password = 'Password used to generate key';
// Key length is dependent on the algorithm. In this case for aes192, it is
// 24 bytes (192 bits).
// Use the async `crypto.scrypt()` instead.
const key = scryptSync(password, 'salt', 24);
// The IV is usually passed along with the ciphertext.
const iv = Buffer.alloc(16, 0); // Initialization vector.

const decipher = createDecipheriv(algorithm, key, iv);

let decrypted = '';
decipher.on('readable', () => {
  let chunk;
  while (null !== (chunk = decipher.read())) {
    decrypted += chunk.toString('utf8');
  }
});
decipher.on('end', () => {
  console.log(decrypted);
  // Prints: some clear text data
});

// Encrypted with same algorithm, key and iv.
const encrypted =
  'e5f79c5915c02171eec6b212d5520d44480993d7d622a7c4c2da32f6efda0ffa';
decipher.write(encrypted, 'hex');
decipher.end();
```

Example: Using `Decipher` and piped streams:

```mjs
import {
  createReadStream,
  createWriteStream,
} from 'node:fs';
import { Buffer } from 'node:buffer';
const {
  scryptSync,
  createDecipheriv,
} = await import('node:crypto');

const algorithm = 'aes-192-cbc';
const password = 'Password used to generate key';
// Use the async `crypto.scrypt()` instead.
const key = scryptSync(password, 'salt', 24);
// The IV is usually passed along with the ciphertext.
const iv = Buffer.alloc(16, 0); // Initialization vector.

const decipher = createDecipheriv(algorithm, key, iv);

const input = createReadStream('test.enc');
const output = createWriteStream('test.js');

input.pipe(decipher).pipe(output);
```

```cjs
const {
  createReadStream,
  createWriteStream,
} = require('node:fs');
const {
  scryptSync,
  createDecipheriv,
} = require('node:crypto');
const { Buffer } = require('node:buffer');

const algorithm = 'aes-192-cbc';
const password = 'Password used to generate key';
// Use the async `crypto.scrypt()` instead.
const key = scryptSync(password, 'salt', 24);
// The IV is usually passed along with the ciphertext.
const iv = Buffer.alloc(16, 0); // Initialization vector.

const decipher = createDecipheriv(algorithm, key, iv);

const input = createReadStream('test.enc');
const output = createWriteStream('test.js');

input.pipe(decipher).pipe(output);
```

Example: Using the [`decipher.update()`][] and [`decipher.final()`][] methods:

```mjs
import { Buffer } from 'node:buffer';
const {
  scryptSync,
  createDecipheriv,
} = await import('node:crypto');

const algorithm = 'aes-192-cbc';
const password = 'Password used to generate key';
// Use the async `crypto.scrypt()` instead.
const key = scryptSync(password, 'salt', 24);
// The IV is usually passed along with the ciphertext.
const iv = Buffer.alloc(16, 0); // Initialization vector.

const decipher = createDecipheriv(algorithm, key, iv);

// Encrypted using same algorithm, key and iv.
const encrypted =
  'e5f79c5915c02171eec6b212d5520d44480993d7d622a7c4c2da32f6efda0ffa';
let decrypted = decipher.update(encrypted, 'hex', 'utf8');
decrypted += decipher.final('utf8');
console.log(decrypted);
// Prints: some clear text data
```

```cjs
const {
  scryptSync,
  createDecipheriv,
} = require('node:crypto');
const { Buffer } = require('node:buffer');

const algorithm = 'aes-192-cbc';
const password = 'Password used to generate key';
// Use the async `crypto.scrypt()` instead.
const key = scryptSync(password, 'salt', 24);
// The IV is usually passed along with the ciphertext.
const iv = Buffer.alloc(16, 0); // Initialization vector.

const decipher = createDecipheriv(algorithm, key, iv);

// Encrypted using same algorithm, key and iv.
const encrypted =
  'e5f79c5915c02171eec6b212d5520d44480993d7d622a7c4c2da32f6efda0ffa';
let decrypted = decipher.update(encrypted, 'hex', 'utf8');
decrypted += decipher.final('utf8');
console.log(decrypted);
// Prints: some clear text data
```

### `decipher.final([outputEncoding])`



* `outputEncoding` {string} The [encoding][] of the return value.
* Returns: {Buffer | string} Any remaining deciphered contents.
  If `outputEncoding` is specified, a string is
  returned. If an `outputEncoding` is not provided, a [`Buffer`][] is returned.

Once the `decipher.final()` method has been called, the `Decipher` object can
no longer be used to decrypt data. Attempts to call `decipher.final()` more
than once will result in an error being thrown.

### `decipher.setAAD(buffer[, options])`



* `buffer` {string|ArrayBuffer|Buffer|TypedArray|DataView}
* `options` {Object} [`stream.transform` options][]
  * `plaintextLength` {number}
  * `encoding` {string} String encoding to use when `buffer` is a string.
* Returns: {Decipher} for method chaining.

When using an authenticated encryption mode (`GCM`, `CCM`, `OCB`, and
`chacha20-poly1305` are
currently supported), the `decipher.setAAD()` method sets the value used for the
_additional authenticated data_ (AAD) input parameter.

The `options` argument is optional for `GCM`. When using `CCM`, the
`plaintextLength` option must be specified and its value must match the length
of the ciphertext in bytes. See [CCM mode][].

The `decipher.setAAD()` method must be called before [`decipher.update()`][].

When passing a string as the `buffer`, please consider
[caveats when using strings as inputs to cryptographic APIs][].

### `decipher.setAuthTag(buffer[, encoding])`



* `buffer` {string|Buffer|ArrayBuffer|TypedArray|DataView}
* `encoding` {string} String encoding to use when `buffer` is a string.
* Returns: {Decipher} for method chaining.

When using an authenticated encryption mode (`GCM`, `CCM`, `OCB`, and
`chacha20-poly1305` are
currently supported), the `decipher.setAuthTag()` method is used to pass in the
received _authentication tag_. If no tag is provided, or if the cipher text
has been tampered with, [`decipher.final()`][] will throw, indicating that the
cipher text should be discarded due to failed authentication. If the tag length
is invalid according to [NIST SP 800-38D][] or does not match the value of the
`authTagLength` option, `decipher.setAuthTag()` will throw an error.

The `decipher.setAuthTag()` method must be called before [`decipher.update()`][]
for `CCM` mode or before [`decipher.final()`][] for `GCM` and `OCB` modes and
`chacha20-poly1305`.
`decipher.setAuthTag()` can only be called once.

When passing a string as the authentication tag, please consider
[caveats when using strings as inputs to cryptographic APIs][].

### `decipher.setAutoPadding([autoPadding])`



* `autoPadding` {boolean} **Default:** `true`
* Returns: {Decipher} for method chaining.

When data has been encrypted without standard block padding, calling
`decipher.setAutoPadding(false)` will disable automatic padding to prevent
[`decipher.final()`][] from checking for and removing padding.

Turning auto padding off will only work if the input data's length is a
multiple of the ciphers block size.

The `decipher.setAutoPadding()` method must be called before
[`decipher.final()`][].

### `decipher.update(data[, inputEncoding][, outputEncoding])`



* `data` {string|Buffer|TypedArray|DataView}
* `inputEncoding` {string} The [encoding][] of the `data` string.
* `outputEncoding` {string} The [encoding][] of the return value.
* Returns: {Buffer | string}

Updates the decipher with `data`. If the `inputEncoding` argument is given,
the `data`
argument is a string using the specified encoding. If the `inputEncoding`
argument is not given, `data` must be a [`Buffer`][]. If `data` is a
[`Buffer`][] then `inputEncoding` is ignored.

The `outputEncoding` specifies the output format of the enciphered
data. If the `outputEncoding`
is specified, a string using the specified encoding is returned. If no
`outputEncoding` is provided, a [`Buffer`][] is returned.

The `decipher.update()` method can be called multiple times with new data until
[`decipher.final()`][] is called. Calling `decipher.update()` after
[`decipher.final()`][] will result in an error being thrown.

## Class: `DiffieHellman`



The `DiffieHellman` class is a utility for creating Diffie-Hellman key
exchanges.

Instances of the `DiffieHellman` class can be created using the
[`crypto.createDiffieHellman()`][] function.

```mjs
import assert from 'node:assert';

const {
  createDiffieHellman,
} = await import('node:crypto');

// Generate Alice's keys...
const alice = createDiffieHellman(2048);
const aliceKey = alice.generateKeys();

// Generate Bob's keys...
const bob = createDiffieHellman(alice.getPrime(), alice.getGenerator());
const bobKey = bob.generateKeys();

// Exchange and generate the secret...
const aliceSecret = alice.computeSecret(bobKey);
const bobSecret = bob.computeSecret(aliceKey);

// OK
assert.strictEqual(aliceSecret.toString('hex'), bobSecret.toString('hex'));
```

```cjs
const assert = require('node:assert');

const {
  createDiffieHellman,
} = require('node:crypto');

// Generate Alice's keys...
const alice = createDiffieHellman(2048);
const aliceKey = alice.generateKeys();

// Generate Bob's keys...
const bob = createDiffieHellman(alice.getPrime(), alice.getGenerator());
const bobKey = bob.generateKeys();

// Exchange and generate the secret...
const aliceSecret = alice.computeSecret(bobKey);
const bobSecret = bob.computeSecret(aliceKey);

// OK
assert.strictEqual(aliceSecret.toString('hex'), bobSecret.toString('hex'));
```

### `diffieHellman.computeSecret(otherPublicKey[, inputEncoding][, outputEncoding])`



* `otherPublicKey` {string|ArrayBuffer|Buffer|TypedArray|DataView}
* `inputEncoding` {string} The [encoding][] of an `otherPublicKey` string.
* `outputEncoding` {string} The [encoding][] of the return value.
* Returns: {Buffer | string}

Computes the shared secret using `otherPublicKey` as the other
party's public key and returns the computed shared secret. The supplied
key is interpreted using the specified `inputEncoding`, and secret is
encoded using specified `outputEncoding`.
If the `inputEncoding` is not
provided, `otherPublicKey` is expected to be a [`Buffer`][],
`TypedArray`, or `DataView`.

If `outputEncoding` is given a string is returned; otherwise, a
[`Buffer`][] is returned.

### `diffieHellman.generateKeys([encoding])`



* `encoding` {string} The [encoding][] of the return value.
* Returns: {Buffer | string}

Generates private and public Diffie-Hellman key values unless they have been
generated or computed already, and returns
the public key in the specified `encoding`. This key should be
transferred to the other party.
If `encoding` is provided a string is returned; otherwise a
[`Buffer`][] is returned.

This function is a thin wrapper around [`DH_generate_key()`][]. In particular,
once a private key has been generated or set, calling this function only updates
the public key but does not generate a new private key.

### `diffieHellman.getGenerator([encoding])`



* `encoding` {string} The [encoding][] of the return value.
* Returns: {Buffer | string}

Returns the Diffie-Hellman generator in the specified `encoding`.
If `encoding` is provided a string is
returned; otherwise a [`Buffer`][] is returned.

### `diffieHellman.getPrime([encoding])`



* `encoding` {string} The [encoding][] of the return value.
* Returns: {Buffer | string}

Returns the Diffie-Hellman prime in the specified `encoding`.
If `encoding` is provided a string is
returned; otherwise a [`Buffer`][] is returned.

### `diffieHellman.getPrivateKey([encoding])`



* `encoding` {string} The [encoding][] of the return value.
* Returns: {Buffer | string}

Returns the Diffie-Hellman private key in the specified `encoding`.
If `encoding` is provided a
string is returned; otherwise a [`Buffer`][] is returned.

### `diffieHellman.getPublicKey([encoding])`



* `encoding` {string} The [encoding][] of the return value.
* Returns: {Buffer | string}

Returns the Diffie-Hellman public key in the specified `encoding`.
If `encoding` is provided a
string is returned; otherwise a [`Buffer`][] is returned.

### `diffieHellman.setPrivateKey(privateKey[, encoding])`



* `privateKey` {string|ArrayBuffer|Buffer|TypedArray|DataView}
* `encoding` {string} The [encoding][] of the `privateKey` string.

Sets the Diffie-Hellman private key. If the `encoding` argument is provided,
`privateKey` is expected
to be a string. If no `encoding` is provided, `privateKey` is expected
to be a [`Buffer`][], `TypedArray`, or `DataView`.

This function does not automatically compute the associated public key. Either
[`diffieHellman.setPublicKey()`][] or [`diffieHellman.generateKeys()`][] can be
used to manually provide the public key or to automatically derive it.

### `diffieHellman.setPublicKey(publicKey[, encoding])`



* `publicKey` {string|ArrayBuffer|Buffer|TypedArray|DataView}
* `encoding` {string} The [encoding][] of the `publicKey` string.

Sets the Diffie-Hellman public key. If the `encoding` argument is provided,
`publicKey` is expected
to be a string. If no `encoding` is provided, `publicKey` is expected
to be a [`Buffer`][], `TypedArray`, or `DataView`.

### `diffieHellman.verifyError`



A bit field containing any warnings and/or errors resulting from a check
performed during initialization of the `DiffieHellman` object.

The following values are valid for this property (as defined in `node:constants` module):

* `DH_CHECK_P_NOT_SAFE_PRIME`
* `DH_CHECK_P_NOT_PRIME`
* `DH_UNABLE_TO_CHECK_GENERATOR`
* `DH_NOT_SUITABLE_GENERATOR`

## Class: `DiffieHellmanGroup`



The `DiffieHellmanGroup` class takes a well-known modp group as its argument.
It works the same as `DiffieHellman`, except that it does not allow changing
its keys after creation. In other words, it does not implement `setPublicKey()`
or `setPrivateKey()` methods.

```mjs
const { createDiffieHellmanGroup } = await import('node:crypto');
const dh = createDiffieHellmanGroup('modp16');
```

```cjs
const { createDiffieHellmanGroup } = require('node:crypto');
const dh = createDiffieHellmanGroup('modp16');
```

The following groups are supported:

* `'modp14'` (2048 bits, [RFC 3526][] Section 3)
* `'modp15'` (3072 bits, [RFC 3526][] Section 4)
* `'modp16'` (4096 bits, [RFC 3526][] Section 5)
* `'modp17'` (6144 bits, [RFC 3526][] Section 6)
* `'modp18'` (8192 bits, [RFC 3526][] Section 7)

The following groups are still supported but deprecated (see [Caveats][]):

* `'modp1'` (768 bits, [RFC 2409][] Section 6.1) 
* `'modp2'` (1024 bits, [RFC 2409][] Section 6.2) 
* `'modp5'` (1536 bits, [RFC 3526][] Section 2) 

These deprecated groups might be removed in future versions of Node.js.

## Class: `ECDH`



The `ECDH` class is a utility for creating Elliptic Curve Diffie-Hellman (ECDH)
key exchanges.

Instances of the `ECDH` class can be created using the
[`crypto.createECDH()`][] function.

```mjs
import assert from 'node:assert';

const {
  createECDH,
} = await import('node:crypto');

// Generate Alice's keys...
const alice = createECDH('secp521r1');
const aliceKey = alice.generateKeys();

// Generate Bob's keys...
const bob = createECDH('secp521r1');
const bobKey = bob.generateKeys();

// Exchange and generate the secret...
const aliceSecret = alice.computeSecret(bobKey);
const bobSecret = bob.computeSecret(aliceKey);

assert.strictEqual(aliceSecret.toString('hex'), bobSecret.toString('hex'));
// OK
```

```cjs
const assert = require('node:assert');

const {
  createECDH,
} = require('node:crypto');

// Generate Alice's keys...
const alice = createECDH('secp521r1');
const aliceKey = alice.generateKeys();

// Generate Bob's keys...
const bob = createECDH('secp521r1');
const bobKey = bob.generateKeys();

// Exchange and generate the secret...
const aliceSecret = alice.computeSecret(bobKey);
const bobSecret = bob.computeSecret(aliceKey);

assert.strictEqual(aliceSecret.toString('hex'), bobSecret.toString('hex'));
// OK
```

### Static method: `ECDH.convertKey(key, curve[, inputEncoding[, outputEncoding[, format]]])`



* `key` {string|ArrayBuffer|Buffer|TypedArray|DataView}
* `curve` {string}
* `inputEncoding` {string} The [encoding][] of the `key` string.
* `outputEncoding` {string} The [encoding][] of the return value.
* `format` {string} **Default:** `'uncompressed'`
* Returns: {Buffer | string}

Converts the EC Diffie-Hellman public key specified by `key` and `curve` to the
format specified by `format`. The `format` argument specifies point encoding
and can be `'compressed'`, `'uncompressed'` or `'hybrid'`. The supplied key is
interpreted using the specified `inputEncoding`, and the returned key is encoded
using the specified `outputEncoding`.

Use [`crypto.getCurves()`][] to obtain a list of available curve names.
On recent OpenSSL releases, `openssl ecparam -list_curves` will also display
the name and description of each available elliptic curve.

If `format` is not specified the point will be returned in `'uncompressed'`
format.

If the `inputEncoding` is not provided, `key` is expected to be a [`Buffer`][],
`TypedArray`, or `DataView`.

Example (uncompressing a key):

```mjs
const {
  createECDH,
  ECDH,
} = await import('node:crypto');

const ecdh = createECDH('secp256k1');
ecdh.generateKeys();

const compressedKey = ecdh.getPublicKey('hex', 'compressed');

const uncompressedKey = ECDH.convertKey(compressedKey,
                                        'secp256k1',
                                        'hex',
                                        'hex',
                                        'uncompressed');

// The converted key and the uncompressed public key should be the same
console.log(uncompressedKey === ecdh.getPublicKey('hex'));
```

```cjs
const {
  createECDH,
  ECDH,
} = require('node:crypto');

const ecdh = createECDH('secp256k1');
ecdh.generateKeys();

const compressedKey = ecdh.getPublicKey('hex', 'compressed');

const uncompressedKey = ECDH.convertKey(compressedKey,
                                        'secp256k1',
                                        'hex',
                                        'hex',
                                        'uncompressed');

// The converted key and the uncompressed public key should be the same
console.log(uncompressedKey === ecdh.getPublicKey('hex'));
```

### `ecdh.computeSecret(otherPublicKey[, inputEncoding][, outputEncoding])`



* `otherPublicKey` {string|ArrayBuffer|Buffer|TypedArray|DataView}
* `inputEncoding` {string} The [encoding][] of the `otherPublicKey` string.
* `outputEncoding` {string} The [encoding][] of the return value.
* Returns: {Buffer | string}

Computes the shared secret using `otherPublicKey` as the other
party's public key and returns the computed shared secret. The supplied
key is interpreted using specified `inputEncoding`, and the returned secret
is encoded using the specified `outputEncoding`.
If the `inputEncoding` is not
provided, `otherPublicKey` is expected to be a [`Buffer`][], `TypedArray`, or
`DataView`.

If `outputEncoding` is given a string will be returned; otherwise a
[`Buffer`][] is returned.

`ecdh.computeSecret` will throw an
`ERR_CRYPTO_ECDH_INVALID_PUBLIC_KEY` error when `otherPublicKey`
lies outside of the elliptic curve. Since `otherPublicKey` is
usually supplied from a remote user over an insecure network,
be sure to handle this exception accordingly.

### `ecdh.generateKeys([encoding[, format]])`



* `encoding` {string} The [encoding][] of the return value.
* `format` {string} **Default:** `'uncompressed'`
* Returns: {Buffer | string}

Generates private and public EC Diffie-Hellman key values, and returns
the public key in the specified `format` and `encoding`. This key should be
transferred to the other party.

The `format` argument specifies point encoding and can be `'compressed'` or
`'uncompressed'`. If `format` is not specified, the point will be returned in
`'uncompressed'` format.

If `encoding` is provided a string is returned; otherwise a [`Buffer`][]
is returned.

### `ecdh.getPrivateKey([encoding])`



* `encoding` {string} The [encoding][] of the return value.
* Returns: {Buffer | string} The EC Diffie-Hellman in the specified `encoding`.

If `encoding` is specified, a string is returned; otherwise a [`Buffer`][] is
returned.

### `ecdh.getPublicKey([encoding][, format])`



* `encoding` {string} The [encoding][] of the return value.
* `format` {string} **Default:** `'uncompressed'`
* Returns: {Buffer | string} The EC Diffie-Hellman public key in the specified
  `encoding` and `format`.

The `format` argument specifies point encoding and can be `'compressed'` or
`'uncompressed'`. If `format` is not specified the point will be returned in
`'uncompressed'` format.

If `encoding` is specified, a string is returned; otherwise a [`Buffer`][] is
returned.

### `ecdh.setPrivateKey(privateKey[, encoding])`



* `privateKey` {string|ArrayBuffer|Buffer|TypedArray|DataView}
* `encoding` {string} The [encoding][] of the `privateKey` string.

Sets the EC Diffie-Hellman private key.
If `encoding` is provided, `privateKey` is expected
to be a string; otherwise `privateKey` is expected to be a [`Buffer`][],
`TypedArray`, or `DataView`.

If `privateKey` is not valid for the curve specified when the `ECDH` object was
created, an error is thrown. Upon setting the private key, the associated
public point (key) is also generated and set in the `ECDH` object.

### `ecdh.setPublicKey(publicKey[, encoding])`



> Stability: 0 - Deprecated

* `publicKey` {string|ArrayBuffer|Buffer|TypedArray|DataView}
* `encoding` {string} The [encoding][] of the `publicKey` string.

Sets the EC Diffie-Hellman public key.
If `encoding` is provided `publicKey` is expected to
be a string; otherwise a [`Buffer`][], `TypedArray`, or `DataView` is expected.

There is not normally a reason to call this method because `ECDH`
only requires a private key and the other party's public key to compute the
shared secret. Typically either [`ecdh.generateKeys()`][] or
[`ecdh.setPrivateKey()`][] will be called. The [`ecdh.setPrivateKey()`][] method
attempts to generate the public point/key associated with the private key being
set.

Example (obtaining a shared secret):

```mjs
const {
  createECDH,
  createHash,
} = await import('node:crypto');

const alice = createECDH('secp256k1');
const bob = createECDH('secp256k1');

// This is a shortcut way of specifying one of Alice's previous private
// keys. It would be unwise to use such a predictable private key in a real
// application.
alice.setPrivateKey(
  createHash('sha256').update('alice', 'utf8').digest(),
);

// Bob uses a newly generated cryptographically strong
// pseudorandom key pair
bob.generateKeys();

const aliceSecret = alice.computeSecret(bob.getPublicKey(), null, 'hex');
const bobSecret = bob.computeSecret(alice.getPublicKey(), null, 'hex');

// aliceSecret and bobSecret should be the same shared secret value
console.log(aliceSecret === bobSecret);
```

```cjs
const {
  createECDH,
  createHash,
} = require('node:crypto');

const alice = createECDH('secp256k1');
const bob = createECDH('secp256k1');

// This is a shortcut way of specifying one of Alice's previous private
// keys. It would be unwise to use such a predictable private key in a real
// application.
alice.setPrivateKey(
  createHash('sha256').update('alice', 'utf8').digest(),
);

// Bob uses a newly generated cryptographically strong
// pseudorandom key pair
bob.generateKeys();

const aliceSecret = alice.computeSecret(bob.getPublicKey(), null, 'hex');
const bobSecret = bob.computeSecret(alice.getPublicKey(), null, 'hex');

// aliceSecret and bobSecret should be the same shared secret value
console.log(aliceSecret === bobSecret);
```

## Class: `Hash`



* Extends: {stream.Transform}

The `Hash` class is a utility for creating hash digests of data. It can be
used in one of two ways:

* As a [stream][] that is both readable and writable, where data is written
  to produce a computed hash digest on the readable side, or
* Using the [`hash.update()`][] and [`hash.digest()`][] methods to produce the
  computed hash.

The [`crypto.createHash()`][] method is used to create `Hash` instances. `Hash`
objects are not to be created directly using the `new` keyword.

Example: Using `Hash` objects as streams:

```mjs
const {
  createHash,
} = await import('node:crypto');

const hash = createHash('sha256');

hash.on('readable', () => {
  // Only one element is going to be produced by the
  // hash stream.
  const data = hash.read();
  if (data) {
    console.log(data.toString('hex'));
    // Prints:
    //   6a2da20943931e9834fc12cfe5bb47bbd9ae43489a30726962b576f4e3993e50
  }
});

hash.write('some data to hash');
hash.end();
```

```cjs
const {
  createHash,
} = require('node:crypto');

const hash = createHash('sha256');

hash.on('readable', () => {
  // Only one element is going to be produced by the
  // hash stream.
  const data = hash.read();
  if (data) {
    console.log(data.toString('hex'));
    // Prints:
    //   6a2da20943931e9834fc12cfe5bb47bbd9ae43489a30726962b576f4e3993e50
  }
});

hash.write('some data to hash');
hash.end();
```

Example: Using `Hash` and piped streams:

```mjs
import { createReadStream } from 'node:fs';
import { stdout } from 'node:process';
const { createHash } = await import('node:crypto');

const hash = createHash('sha256');

const input = createReadStream('test.js');
input.pipe(hash).setEncoding('hex').pipe(stdout);
```

```cjs
const { createReadStream } = require('node:fs');
const { createHash } = require('node:crypto');
const { stdout } = require('node:process');

const hash = createHash('sha256');

const input = createReadStream('test.js');
input.pipe(hash).setEncoding('hex').pipe(stdout);
```

Example: Using the [`hash.update()`][] and [`hash.digest()`][] methods:

```mjs
const {
  createHash,
} = await import('node:crypto');

const hash = createHash('sha256');

hash.update('some data to hash');
console.log(hash.digest('hex'));
// Prints:
//   6a2da20943931e9834fc12cfe5bb47bbd9ae43489a30726962b576f4e3993e50
```

```cjs
const {
  createHash,
} = require('node:crypto');

const hash = createHash('sha256');

hash.update('some data to hash');
console.log(hash.digest('hex'));
// Prints:
//   6a2da20943931e9834fc12cfe5bb47bbd9ae43489a30726962b576f4e3993e50
```

### `hash.copy([options])`



* `options` {Object} [`stream.transform` options][]
* Returns: {Hash}

Creates a new `Hash` object that contains a deep copy of the internal state
of the current `Hash` object.

The optional `options` argument controls stream behavior. For XOF hash
functions such as `'shake256'`, the `outputLength` option can be used to
specify the desired output length in bytes.

An error is thrown when an attempt is made to copy the `Hash` object after
its [`hash.digest()`][] method has been called.

```mjs
// Calculate a rolling hash.
const {
  createHash,
} = await import('node:crypto');

const hash = createHash('sha256');

hash.update('one');
console.log(hash.copy().digest('hex'));

hash.update('two');
console.log(hash.copy().digest('hex'));

hash.update('three');
console.log(hash.copy().digest('hex'));

// Etc.
```

```cjs
// Calculate a rolling hash.
const {
  createHash,
} = require('node:crypto');

const hash = createHash('sha256');

hash.update('one');
console.log(hash.copy().digest('hex'));

hash.update('two');
console.log(hash.copy().digest('hex'));

hash.update('three');
console.log(hash.copy().digest('hex'));

// Etc.
```

### `hash.digest([encoding])`



* `encoding` {string} The [encoding][] of the return value.
* Returns: {Buffer | string}

Calculates the digest of all of the data passed to be hashed (using the
[`hash.update()`][] method).
If `encoding` is provided a string will be returned; otherwise
a [`Buffer`][] is returned.

The `Hash` object can not be used again after `hash.digest()` method has been
called. Multiple calls will cause an error to be thrown.

### `hash.update(data[, inputEncoding])`



* `data` {string|Buffer|TypedArray|DataView}
* `inputEncoding` {string} The [encoding][] of the `data` string.

Updates the hash content with the given `data`, the encoding of which
is given in `inputEncoding`.
If `encoding` is not provided, and the `data` is a string, an
encoding of `'utf8'` is enforced. If `data` is a [`Buffer`][], `TypedArray`, or
`DataView`, then `inputEncoding` is ignored.

This can be called many times with new data as it is streamed.

## Class: `Hmac`



* Extends: {stream.Transform}

The `Hmac` class is a utility for creating cryptographic HMAC digests. It can
be used in one of two ways:

* As a [stream][] that is both readable and writable, where data is written
  to produce a computed HMAC digest on the readable side, or
* Using the [`hmac.update()`][] and [`hmac.digest()`][] methods to produce the
  computed HMAC digest.

The [`crypto.createHmac()`][] method is used to create `Hmac` instances. `Hmac`
objects are not to be created directly using the `new` keyword.

Example: Using `Hmac` objects as streams:

```mjs
const {
  createHmac,
} = await import('node:crypto');

const hmac = createHmac('sha256', 'a secret');

hmac.on('readable', () => {
  // Only one element is going to be produced by the
  // hash stream.
  const data = hmac.read();
  if (data) {
    console.log(data.toString('hex'));
    // Prints:
    //   7fd04df92f636fd450bc841c9418e5825c17f33ad9c87c518115a45971f7f77e
  }
});

hmac.write('some data to hash');
hmac.end();
```

```cjs
const {
  createHmac,
} = require('node:crypto');

const hmac = createHmac('sha256', 'a secret');

hmac.on('readable', () => {
  // Only one element is going to be produced by the
  // hash stream.
  const data = hmac.read();
  if (data) {
    console.log(data.toString('hex'));
    // Prints:
    //   7fd04df92f636fd450bc841c9418e5825c17f33ad9c87c518115a45971f7f77e
  }
});

hmac.write('some data to hash');
hmac.end();
```

Example: Using `Hmac` and piped streams:

```mjs
import { createReadStream } from 'node:fs';
import { stdout } from 'node:process';
const {
  createHmac,
} = await import('node:crypto');

const hmac = createHmac('sha256', 'a secret');

const input = createReadStream('test.js');
input.pipe(hmac).pipe(stdout);
```

```cjs
const {
  createReadStream,
} = require('node:fs');
const {
  createHmac,
} = require('node:crypto');
const { stdout } = require('node:process');

const hmac = createHmac('sha256', 'a secret');

const input = createReadStream('test.js');
input.pipe(hmac).pipe(stdout);
```

Example: Using the [`hmac.update()`][] and [`hmac.digest()`][] methods:

```mjs
const {
  createHmac,
} = await import('node:crypto');

const hmac = createHmac('sha256', 'a secret');

hmac.update('some data to hash');
console.log(hmac.digest('hex'));
// Prints:
//   7fd04df92f636fd450bc841c9418e5825c17f33ad9c87c518115a45971f7f77e
```

```cjs
const {
  createHmac,
} = require('node:crypto');

const hmac = createHmac('sha256', 'a secret');

hmac.update('some data to hash');
console.log(hmac.digest('hex'));
// Prints:
//   7fd04df92f636fd450bc841c9418e5825c17f33ad9c87c518115a45971f7f77e
```

### `hmac.digest([encoding])`



* `encoding` {string} The [encoding][] of the return value.
* Returns: {Buffer | string}

Calculates the HMAC digest of all of the data passed using [`hmac.update()`][].
If `encoding` is
provided a string is returned; otherwise a [`Buffer`][] is returned;

The `Hmac` object can not be used again after `hmac.digest()` has been
called. Multiple calls to `hmac.digest()` will result in an error being thrown.

### `hmac.update(data[, inputEncoding])`



* `data` {string|Buffer|TypedArray|DataView}
* `inputEncoding` {string} The [encoding][] of the `data` string.

Updates the `Hmac` content with the given `data`, the encoding of which
is given in `inputEncoding`.
If `encoding` is not provided, and the `data` is a string, an
encoding of `'utf8'` is enforced. If `data` is a [`Buffer`][], `TypedArray`, or
`DataView`, then `inputEncoding` is ignored.

This can be called many times with new data as it is streamed.

## Class: `KeyObject`



Node.js uses a `KeyObject` class to represent a symmetric or asymmetric key,
and each kind of key exposes different functions. The
[`crypto.createSecretKey()`][], [`crypto.createPublicKey()`][] and
[`crypto.createPrivateKey()`][] methods are used to create `KeyObject`
instances. `KeyObject` objects are not to be created directly using the `new`
keyword.

Most applications should consider using the new `KeyObject` API instead of
passing keys as strings or `Buffer`s due to improved security features.

`KeyObject` instances can be passed to other threads via [`postMessage()`][].
The receiver obtains a cloned `KeyObject`, and the `KeyObject` does not need to
be listed in the `transferList` argument.

### Static method: `KeyObject.from(key)`



* `key` {CryptoKey}
* Returns: {KeyObject}

Example: Converting a `CryptoKey` instance to a `KeyObject`:

```mjs
const { webcrypto, KeyObject } = await import('node:crypto');
const { subtle } = webcrypto;

const key = await subtle.generateKey({
  name: 'HMAC',
  hash: 'SHA-256',
  length: 256,
}, true, ['sign', 'verify']);

const keyObject = KeyObject.from(key);
console.log(keyObject.symmetricKeySize);
// Prints: 32 (symmetric key size in bytes)
```

```cjs
const {
  webcrypto: {
    subtle,
  },
  KeyObject,
} = require('node:crypto');

(async function() {
  const key = await subtle.generateKey({
    name: 'HMAC',
    hash: 'SHA-256',
    length: 256,
  }, true, ['sign', 'verify']);

  const keyObject = KeyObject.from(key);
  console.log(keyObject.symmetricKeySize);
  // Prints: 32 (symmetric key size in bytes)
})();
```

### `keyObject.asymmetricKeyDetails`



* {Object}
  * `modulusLength`: {number} Key size in bits (RSA, DSA).
  * `publicExponent`: {bigint} Public exponent (RSA).
  * `hashAlgorithm`: {string} Name of the message digest (RSA-PSS).
  * `mgf1HashAlgorithm`: {string} Name of the message digest used by
    MGF1 (RSA-PSS).
  * `saltLength`: {number} Minimal salt length in bytes (RSA-PSS).
  * `divisorLength`: {number} Size of `q` in bits (DSA).
  * `namedCurve`: {string} Name of the curve (EC).

This property exists only on asymmetric keys. Depending on the type of the key,
this object contains information about the key. None of the information obtained
through this property can be used to uniquely identify a key or to compromise
the security of the key.

For RSA-PSS keys, if the key material contains a `RSASSA-PSS-params` sequence,
the `hashAlgorithm`, `mgf1HashAlgorithm`, and `saltLength` properties will be
set.

Other key details might be exposed via this API using additional attributes.

### `keyObject.asymmetricKeyType`



* {string}

For asymmetric keys, this property represents the type of the key. Supported key
types are:

* `'rsa'` (OID 1.2.840.113549.1.1.1)
* `'rsa-pss'` (OID 1.2.840.113549.1.1.10)
* `'dsa'` (OID 1.2.840.10040.4.1)
* `'ec'` (OID 1.2.840.10045.2.1)
* `'x25519'` (OID 1.3.101.110)
* `'x448'` (OID 1.3.101.111)
* `'ed25519'` (OID 1.3.101.112)
* `'ed448'` (OID 1.3.101.113)
* `'dh'` (OID 1.2.840.113549.1.3.1)

This property is `undefined` for unrecognized `KeyObject` types and symmetric
keys.

### `keyObject.export([options])`



* `options`: {Object}
* Returns: {string | Buffer | Object}

For symmetric keys, the following encoding options can be used:

* `format`: {string} Must be `'buffer'` (default) or `'jwk'`.

For public keys, the following encoding options can be used:

* `type`: {string} Must be one of `'pkcs1'` (RSA only) or `'spki'`.
* `format`: {string} Must be `'pem'`, `'der'`, or `'jwk'`.

For private keys, the following encoding options can be used:

* `type`: {string} Must be one of `'pkcs1'` (RSA only), `'pkcs8'` or
  `'sec1'` (EC only).
* `format`: {string} Must be `'pem'`, `'der'`, or `'jwk'`.
* `cipher`: {string} If specified, the private key will be encrypted with
  the given `cipher` and `passphrase` using PKCS#5 v2.0 password based
  encryption.
* `passphrase`: {string | Buffer} The passphrase to use for encryption, see
  `cipher`.

The result type depends on the selected encoding format, when PEM the
result is a string, when DER it will be a buffer containing the data
encoded as DER, when [JWK][] it will be an object.

When [JWK][] encoding format was selected, all other encoding options are
ignored.

PKCS#1, SEC1, and PKCS#8 type keys can be encrypted by using a combination of
the `cipher` and `format` options. The PKCS#8 `type` can be used with any
`format` to encrypt any key algorithm (RSA, EC, or DH) by specifying a
`cipher`. PKCS#1 and SEC1 can only be encrypted by specifying a `cipher`
when the PEM `format` is used. For maximum compatibility, use PKCS#8 for
encrypted private keys. Since PKCS#8 defines its own
encryption mechanism, PEM-level encryption is not supported when encrypting
a PKCS#8 key. See [RFC 5208][] for PKCS#8 encryption and [RFC 1421][] for
PKCS#1 and SEC1 encryption.

### `keyObject.equals(otherKeyObject)`



* `otherKeyObject`: {KeyObject} A `KeyObject` with which to
  compare `keyObject`.
* Returns: {boolean}

Returns `true` or `false` depending on whether the keys have exactly the same
type, value, and parameters. This method is not
[constant time](https://en.wikipedia.org/wiki/Timing_attack).

### `keyObject.symmetricKeySize`



* {number}

For secret keys, this property represents the size of the key in bytes. This
property is `undefined` for asymmetric keys.

### `keyObject.type`



* {string}

Depending on the type of this `KeyObject`, this property is either
`'secret'` for secret (symmetric) keys, `'public'` for public (asymmetric) keys
or `'private'` for private (asymmetric) keys.

## Class: `Sign`



* Extends: {stream.Writable}

The `Sign` class is a utility for generating signatures. It can be used in one
of two ways:

* As a writable [stream][], where data to be signed is written and the
  [`sign.sign()`][] method is used to generate and return the signature, or
* Using the [`sign.update()`][] and [`sign.sign()`][] methods to produce the
  signature.

The [`crypto.createSign()`][] method is used to create `Sign` instances. The
argument is the string name of the hash function to use. `Sign` objects are not
to be created directly using the `new` keyword.

Example: Using `Sign` and [`Verify`][] objects as streams:

```mjs
const {
  generateKeyPairSync,
  createSign,
  createVerify,
} = await import('node:crypto');

const { privateKey, publicKey } = generateKeyPairSync('ec', {
  namedCurve: 'sect239k1',
});

const sign = createSign('SHA256');
sign.write('some data to sign');
sign.end();
const signature = sign.sign(privateKey, 'hex');

const verify = createVerify('SHA256');
verify.write('some data to sign');
verify.end();
console.log(verify.verify(publicKey, signature, 'hex'));
// Prints: true
```

```cjs
const {
  generateKeyPairSync,
  createSign,
  createVerify,
} = require('node:crypto');

const { privateKey, publicKey } = generateKeyPairSync('ec', {
  namedCurve: 'sect239k1',
});

const sign = createSign('SHA256');
sign.write('some data to sign');
sign.end();
const signature = sign.sign(privateKey, 'hex');

const verify = createVerify('SHA256');
verify.write('some data to sign');
verify.end();
console.log(verify.verify(publicKey, signature, 'hex'));
// Prints: true
```

Example: Using the [`sign.update()`][] and [`verify.update()`][] methods:

```mjs
const {
  generateKeyPairSync,
  createSign,
  createVerify,
} = await import('node:crypto');

const { privateKey, publicKey } = generateKeyPairSync('rsa', {
  modulusLength: 2048,
});

const sign = createSign('SHA256');
sign.update('some data to sign');
sign.end();
const signature = sign.sign(privateKey);

const verify = createVerify('SHA256');
verify.update('some data to sign');
verify.end();
console.log(verify.verify(publicKey, signature));
// Prints: true
```

```cjs
const {
  generateKeyPairSync,
  createSign,
  createVerify,
} = require('node:crypto');

const { privateKey, publicKey } = generateKeyPairSync('rsa', {
  modulusLength: 2048,
});

const sign = createSign('SHA256');
sign.update('some data to sign');
sign.end();
const signature = sign.sign(privateKey);

const verify = createVerify('SHA256');
verify.update('some data to sign');
verify.end();
console.log(verify.verify(publicKey, signature));
// Prints: true
```

### `sign.sign(privateKey[, outputEncoding])`





* `privateKey` {Object|string|ArrayBuffer|Buffer|TypedArray|DataView|KeyObject|CryptoKey}
  * `dsaEncoding` {string}
  * `padding` {integer}
  * `saltLength` {integer}
* `outputEncoding` {string} The [encoding][] of the return value.
* Returns: {Buffer | string}



Calculates the signature on all the data passed through using either
[`sign.update()`][] or [`sign.write()`][stream-writable-write].

If `privateKey` is not a [`KeyObject`][], this function behaves as if
`privateKey` had been passed to [`crypto.createPrivateKey()`][]. If it is an
object, the following additional properties can be passed:

* `dsaEncoding` {string} For DSA and ECDSA, this option specifies the
  format of the generated signature. It can be one of the following:
  * `'der'` (default): DER-encoded ASN.1 signature structure encoding `(r, s)`.
  * `'ieee-p1363'`: Signature format `r || s` as proposed in IEEE-P1363.
* `padding` {integer} Optional padding value for RSA, one of the following:

  * `crypto.constants.RSA_PKCS1_PADDING` (default)
  * `crypto.constants.RSA_PKCS1_PSS_PADDING`

  `RSA_PKCS1_PSS_PADDING` will use MGF1 with the same hash function
  used to sign the message as specified in section 3.1 of [RFC 4055][], unless
  an MGF1 hash function has been specified as part of the key in compliance with
  section 3.3 of [RFC 4055][].
* `saltLength` {integer} Salt length for when padding is
  `RSA_PKCS1_PSS_PADDING`. The special value
  `crypto.constants.RSA_PSS_SALTLEN_DIGEST` sets the salt length to the digest
  size, `crypto.constants.RSA_PSS_SALTLEN_MAX_SIGN` (default) sets it to the
  maximum permissible value.

If `outputEncoding` is provided a string is returned; otherwise a [`Buffer`][]
is returned.

The `Sign` object can not be again used after `sign.sign()` method has been
called. Multiple calls to `sign.sign()` will result in an error being thrown.

### `sign.update(data[, inputEncoding])`



* `data` {string|Buffer|TypedArray|DataView}
* `inputEncoding` {string} The [encoding][] of the `data` string.

Updates the `Sign` content with the given `data`, the encoding of which
is given in `inputEncoding`.
If `encoding` is not provided, and the `data` is a string, an
encoding of `'utf8'` is enforced. If `data` is a [`Buffer`][], `TypedArray`, or
`DataView`, then `inputEncoding` is ignored.

This can be called many times with new data as it is streamed.

## Class: `Verify`



* Extends: {stream.Writable}

The `Verify` class is a utility for verifying signatures. It can be used in one
of two ways:

* As a writable [stream][] where written data is used to validate against the
  supplied signature, or
* Using the [`verify.update()`][] and [`verify.verify()`][] methods to verify
  the signature.

The [`crypto.createVerify()`][] method is used to create `Verify` instances.
`Verify` objects are not to be created directly using the `new` keyword.

See [`Sign`][] for examples.

### `verify.update(data[, inputEncoding])`



* `data` {string|Buffer|TypedArray|DataView}
* `inputEncoding` {string} The [encoding][] of the `data` string.

Updates the `Verify` content with the given `data`, the encoding of which
is given in `inputEncoding`.
If `inputEncoding` is not provided, and the `data` is a string, an
encoding of `'utf8'` is enforced. If `data` is a [`Buffer`][], `TypedArray`, or
`DataView`, then `inputEncoding` is ignored.

This can be called many times with new data as it is streamed.

### `verify.verify(object, signature[, signatureEncoding])`





* `object` {Object|string|ArrayBuffer|Buffer|TypedArray|DataView|KeyObject|CryptoKey}
  * `dsaEncoding` {string}
  * `padding` {integer}
  * `saltLength` {integer}
* `signature` {string|ArrayBuffer|Buffer|TypedArray|DataView}
* `signatureEncoding` {string} The [encoding][] of the `signature` string.
* Returns: {boolean} `true` or `false` depending on the validity of the
  signature for the data and public key.



Verifies the provided data using the given `object` and `signature`.

If `object` is not a [`KeyObject`][], this function behaves as if
`object` had been passed to [`crypto.createPublicKey()`][]. If it is an
object, the following additional properties can be passed:

* `dsaEncoding` {string} For DSA and ECDSA, this option specifies the
  format of the signature. It can be one of the following:
  * `'der'` (default): DER-encoded ASN.1 signature structure encoding `(r, s)`.
  * `'ieee-p1363'`: Signature format `r || s` as proposed in IEEE-P1363.
* `padding` {integer} Optional padding value for RSA, one of the following:

  * `crypto.constants.RSA_PKCS1_PADDING` (default)
  * `crypto.constants.RSA_PKCS1_PSS_PADDING`

  `RSA_PKCS1_PSS_PADDING` will use MGF1 with the same hash function
  used to verify the message as specified in section 3.1 of [RFC 4055][], unless
  an MGF1 hash function has been specified as part of the key in compliance with
  section 3.3 of [RFC 4055][].
* `saltLength` {integer} Salt length for when padding is
  `RSA_PKCS1_PSS_PADDING`. The special value
  `crypto.constants.RSA_PSS_SALTLEN_DIGEST` sets the salt length to the digest
  size, `crypto.constants.RSA_PSS_SALTLEN_AUTO` (default) causes it to be
  determined automatically.

The `signature` argument is the previously calculated signature for the data, in
the `signatureEncoding`.
If a `signatureEncoding` is specified, the `signature` is expected to be a
string; otherwise `signature` is expected to be a [`Buffer`][],
`TypedArray`, or `DataView`.

The `verify` object can not be used again after `verify.verify()` has been
called. Multiple calls to `verify.verify()` will result in an error being
thrown.

Because public keys can be derived from private keys, a private key may
be passed instead of a public key.

## Class: `X509Certificate`



Encapsulates an X509 certificate and provides read-only access to
its information.

```mjs
const { X509Certificate } = await import('node:crypto');

const x509 = new X509Certificate('{... pem encoded cert ...}');

console.log(x509.subject);
```

```cjs
const { X509Certificate } = require('node:crypto');

const x509 = new X509Certificate('{... pem encoded cert ...}');

console.log(x509.subject);
```

### `new X509Certificate(buffer)`



* `buffer` {string|TypedArray|Buffer|DataView} A PEM or DER encoded
  X509 Certificate.

### `x509.ca`



* Type: {boolean} Will be `true` if this is a Certificate Authority (CA)
  certificate.

### `x509.checkEmail(email[, options])`



* `email` {string}
* `options` {Object}
  * `subject` {string} `'default'`, `'always'`, or `'never'`.
    **Default:** `'default'`.
* Returns: {string|undefined} Returns `email` if the certificate matches,
  `undefined` if it does not.

Checks whether the certificate matches the given email address.

If the `'subject'` option is undefined or set to `'default'`, the certificate
subject is only considered if the subject alternative name extension either does
not exist or does not contain any email addresses.

If the `'subject'` option is set to `'always'` and if the subject alternative
name extension either does not exist or does not contain a matching email
address, the certificate subject is considered.

If the `'subject'` option is set to `'never'`, the certificate subject is never
considered, even if the certificate contains no subject alternative names.

### `x509.checkHost(name[, options])`



* `name` {string}
* `options` {Object}
  * `subject` {string} `'default'`, `'always'`, or `'never'`.
    **Default:** `'default'`.
  * `wildcards` {boolean} **Default:** `true`.
  * `partialWildcards` {boolean} **Default:** `true`.
  * `multiLabelWildcards` {boolean} **Default:** `false`.
  * `singleLabelSubdomains` {boolean} **Default:** `false`.
* Returns: {string|undefined} Returns a subject name that matches `name`,
  or `undefined` if no subject name matches `name`.

Checks whether the certificate matches the given host name.

If the certificate matches the given host name, the matching subject name is
returned. The returned name might be an exact match (e.g., `foo.example.com`)
or it might contain wildcards (e.g., `*.example.com`). Because host name
comparisons are case-insensitive, the returned subject name might also differ
from the given `name` in capitalization.

If the `'subject'` option is undefined or set to `'default'`, the certificate
subject is only considered if the subject alternative name extension either does
not exist or does not contain any DNS names. This behavior is consistent with
[RFC 2818][] ("HTTP Over TLS").

If the `'subject'` option is set to `'always'` and if the subject alternative
name extension either does not exist or does not contain a matching DNS name,
the certificate subject is considered.

If the `'subject'` option is set to `'never'`, the certificate subject is never
considered, even if the certificate contains no subject alternative names.

### `x509.checkIP(ip)`



* `ip` {string}
* Returns: {string|undefined} Returns `ip` if the certificate matches,
  `undefined` if it does not.

Checks whether the certificate matches the given IP address (IPv4 or IPv6).

Only [RFC 5280][] `iPAddress` subject alternative names are considered, and they
must match the given `ip` address exactly. Other subject alternative names as
well as the subject field of the certificate are ignored.

### `x509.checkIssued(otherCert)`



* `otherCert` {X509Certificate}
* Returns: {boolean}

Checks whether this certificate was issued by the given `otherCert`.

### `x509.checkPrivateKey(privateKey)`



* `privateKey` {KeyObject} A private key.
* Returns: {boolean}

Checks whether the public key for this certificate is consistent with
the given private key.

### `x509.fingerprint`



* Type: {string}

The SHA-1 fingerprint of this certificate.

Because SHA-1 is cryptographically broken and because the security of SHA-1 is
significantly worse than that of algorithms that are commonly used to sign
certificates, consider using [`x509.fingerprint256`][] instead.

### `x509.fingerprint256`



* Type: {string}

The SHA-256 fingerprint of this certificate.

### `x509.fingerprint512`



* Type: {string}

The SHA-512 fingerprint of this certificate.

Because computing the SHA-256 fingerprint is usually faster and because it is
only half the size of the SHA-512 fingerprint, [`x509.fingerprint256`][] may be
a better choice. While SHA-512 presumably provides a higher level of security in
general, the security of SHA-256 matches that of most algorithms that are
commonly used to sign certificates.

### `x509.infoAccess`



* Type: {string}

A textual representation of the certificate's authority information access
extension.

This is a line feed separated list of access descriptions. Each line begins with
the access method and the kind of the access location, followed by a colon and
the value associated with the access location.

After the prefix denoting the access method and the kind of the access location,
the remainder of each line might be enclosed in quotes to indicate that the
value is a JSON string literal. For backward compatibility, Node.js only uses
JSON string literals within this property when necessary to avoid ambiguity.
Third-party code should be prepared to handle both possible entry formats.

### `x509.issuer`



* Type: {string}

The issuer identification included in this certificate.

### `x509.issuerCertificate`



* Type: {X509Certificate}

The issuer certificate or `undefined` if the issuer certificate is not
available.

### `x509.keyUsage`



* Type: {string\[]}

An array detailing the key usages for this certificate.

### `x509.publicKey`



* Type: {KeyObject}

The public key {KeyObject} for this certificate.

### `x509.raw`



* Type: {Buffer}

A `Buffer` containing the DER encoding of this certificate.

### `x509.serialNumber`



* Type: {string}

The serial number of this certificate.

Serial numbers are assigned by certificate authorities and do not uniquely
identify certificates. Consider using [`x509.fingerprint256`][] as a unique
identifier instead.

### `x509.subject`



* Type: {string}

The complete subject of this certificate.

### `x509.subjectAltName`



* Type: {string}

The subject alternative name specified for this certificate.

This is a comma-separated list of subject alternative names. Each entry begins
with a string identifying the kind of the subject alternative name followed by
a colon and the value associated with the entry.

Earlier versions of Node.js incorrectly assumed that it is safe to split this
property at the two-character sequence `', '` (see [CVE-2021-44532][]). However,
both malicious and legitimate certificates can contain subject alternative names
that include this sequence when represented as a string.

After the prefix denoting the type of the entry, the remainder of each entry
might be enclosed in quotes to indicate that the value is a JSON string literal.
For backward compatibility, Node.js only uses JSON string literals within this
property when necessary to avoid ambiguity. Third-party code should be prepared
to handle both possible entry formats.

### `x509.toJSON()`



* Type: {string}

There is no standard JSON encoding for X509 certificates. The
`toJSON()` method returns a string containing the PEM encoded
certificate.

### `x509.toLegacyObject()`



* Type: {Object}

Returns information about this certificate using the legacy
[certificate object][] encoding.

### `x509.toString()`



* Type: {string}

Returns the PEM-encoded certificate.

### `x509.validFrom`



* Type: {string}

The date/time from which this certificate is considered valid.

### `x509.validTo`



* Type: {string}

The date/time until which this certificate is considered valid.

### `x509.verify(publicKey)`



* `publicKey` {KeyObject} A public key.
* Returns: {boolean}

Verifies that this certificate was signed by the given public key.
Does not perform any other validation checks on the certificate.

## `node:crypto` module methods and properties

### `crypto.constants`



* {Object}

An object containing commonly used constants for crypto and security related
operations. The specific constants currently defined are described in
[Crypto constants][].

### `crypto.DEFAULT_ENCODING`



> Stability: 0 - Deprecated

The default encoding to use for functions that can take either strings
or [buffers][`Buffer`]. The default value is `'buffer'`, which makes methods
default to [`Buffer`][] objects.

The `crypto.DEFAULT_ENCODING` mechanism is provided for backward compatibility
with legacy programs that expect `'latin1'` to be the default encoding.

New applications should expect the default to be `'buffer'`.

This property is deprecated.

### `crypto.fips`



> Stability: 0 - Deprecated

Property for checking and controlling whether a FIPS compliant crypto provider
is currently in use. Setting to true requires a FIPS build of Node.js.

This property is deprecated. Please use `crypto.setFips()` and
`crypto.getFips()` instead.

### `crypto.checkPrime(candidate[, options], callback)`



* `candidate` {ArrayBuffer|SharedArrayBuffer|TypedArray|Buffer|DataView|bigint}
  A possible prime encoded as a sequence of big endian octets of arbitrary
  length.
* `options` {Object}
  * `checks` {number} The number of Miller-Rabin probabilistic primality
    iterations to perform. When the value is `0` (zero), a number of checks
    is used that yields a false positive rate of at most 2-64 for
    random input. Care must be used when selecting a number of checks. Refer
    to the OpenSSL documentation for the [`BN_is_prime_ex`][] function `nchecks`
    options for more details. **Default:** `0`
* `callback` {Function}
  * `err` {Error} Set to an {Error} object if an error occurred during check.
  * `result` {boolean} `true` if the candidate is a prime with an error
    probability less than `0.25 ** options.checks`.

Checks the primality of the `candidate`.

### `crypto.checkPrimeSync(candidate[, options])`



* `candidate` {ArrayBuffer|SharedArrayBuffer|TypedArray|Buffer|DataView|bigint}
  A possible prime encoded as a sequence of big endian octets of arbitrary
  length.
* `options` {Object}
  * `checks` {number} The number of Miller-Rabin probabilistic primality
    iterations to perform. When the value is `0` (zero), a number of checks
    is used that yields a false positive rate of at most 2-64 for
    random input. Care must be used when selecting a number of checks. Refer
    to the OpenSSL documentation for the [`BN_is_prime_ex`][] function `nchecks`
    options for more details. **Default:** `0`
* Returns: {boolean} `true` if the candidate is a prime with an error
  probability less than `0.25 ** options.checks`.

Checks the primality of the `candidate`.

### `crypto.createCipher(algorithm, password[, options])`



> Stability: 0 - Deprecated: Use [`crypto.createCipheriv()`][] instead.

* `algorithm` {string}
* `password` {string|ArrayBuffer|Buffer|TypedArray|DataView}
* `options` {Object} [`stream.transform` options][]
* Returns: {Cipher}

Creates and returns a `Cipher` object that uses the given `algorithm` and
`password`.

The `options` argument controls stream behavior and is optional except when a
cipher in CCM or OCB mode (e.g. `'aes-128-ccm'`) is used. In that case, the
`authTagLength` option is required and specifies the length of the
authentication tag in bytes, see [CCM mode][]. In GCM mode, the `authTagLength`
option is not required but can be used to set the length of the authentication
tag that will be returned by `getAuthTag()` and defaults to 16 bytes.
For `chacha20-poly1305`, the `authTagLength` option defaults to 16 bytes.

The `algorithm` is dependent on OpenSSL, examples are `'aes192'`, etc. On
recent OpenSSL releases, `openssl list -cipher-algorithms` will
display the available cipher algorithms.

The `password` is used to derive the cipher key and initialization vector (IV).
The value must be either a `'latin1'` encoded string, a [`Buffer`][], a
`TypedArray`, or a `DataView`.

This function is semantically insecure for all
supported ciphers and fatally flawed for ciphers in counter mode (such as CTR,
GCM, or CCM).

The implementation of `crypto.createCipher()` derives keys using the OpenSSL
function [`EVP_BytesToKey`][] with the digest algorithm set to MD5, one
iteration, and no salt. The lack of salt allows dictionary attacks as the same
password always creates the same key. The low iteration count and
non-cryptographically secure hash algorithm allow passwords to be tested very
rapidly.

In line with OpenSSL's recommendation to use a more modern algorithm instead of
[`EVP_BytesToKey`][] it is recommended that developers derive a key and IV on
their own using [`crypto.scrypt()`][] and to use [`crypto.createCipheriv()`][]
to create the `Cipher` object. Users should not use ciphers with counter mode
(e.g. CTR, GCM, or CCM) in `crypto.createCipher()`. A warning is emitted when
they are used in order to avoid the risk of IV reuse that causes
vulnerabilities. For the case when IV is reused in GCM, see [Nonce-Disrespecting
Adversaries][] for details.

### `crypto.createCipheriv(algorithm, key, iv[, options])`



* `algorithm` {string}
* `key` {string|ArrayBuffer|Buffer|TypedArray|DataView|KeyObject|CryptoKey}
* `iv` {string|ArrayBuffer|Buffer|TypedArray|DataView|null}
* `options` {Object} [`stream.transform` options][]
* Returns: {Cipher}

Creates and returns a `Cipher` object, with the given `algorithm`, `key` and
initialization vector (`iv`).

The `options` argument controls stream behavior and is optional except when a
cipher in CCM or OCB mode (e.g. `'aes-128-ccm'`) is used. In that case, the
`authTagLength` option is required and specifies the length of the
authentication tag in bytes, see [CCM mode][]. In GCM mode, the `authTagLength`
option is not required but can be used to set the length of the authentication
tag that will be returned by `getAuthTag()` and defaults to 16 bytes.
For `chacha20-poly1305`, the `authTagLength` option defaults to 16 bytes.

The `algorithm` is dependent on OpenSSL, examples are `'aes192'`, etc. On
recent OpenSSL releases, `openssl list -cipher-algorithms` will
display the available cipher algorithms.

The `key` is the raw key used by the `algorithm` and `iv` is an
[initialization vector][]. Both arguments must be `'utf8'` encoded strings,
[Buffers][`Buffer`], `TypedArray`, or `DataView`s. The `key` may optionally be
a [`KeyObject`][] of type `secret`. If the cipher does not need
an initialization vector, `iv` may be `null`.

When passing strings for `key` or `iv`, please consider
[caveats when using strings as inputs to cryptographic APIs][].

Initialization vectors should be unpredictable and unique; ideally, they will be
cryptographically random. They do not have to be secret: IVs are typically just
added to ciphertext messages unencrypted. It may sound contradictory that
something has to be unpredictable and unique, but does not have to be secret;
remember that an attacker must not be able to predict ahead of time what a
given IV will be.

### `crypto.createDecipher(algorithm, password[, options])`



> Stability: 0 - Deprecated: Use [`crypto.createDecipheriv()`][] instead.

* `algorithm` {string}
* `password` {string|ArrayBuffer|Buffer|TypedArray|DataView}
* `options` {Object} [`stream.transform` options][]
* Returns: {Decipher}

Creates and returns a `Decipher` object that uses the given `algorithm` and
`password` (key).

The `options` argument controls stream behavior and is optional except when a
cipher in CCM or OCB mode (e.g. `'aes-128-ccm'`) is used. In that case, the
`authTagLength` option is required and specifies the length of the
authentication tag in bytes, see [CCM mode][].
For `chacha20-poly1305`, the `authTagLength` option defaults to 16 bytes.

This function is semantically insecure for all
supported ciphers and fatally flawed for ciphers in counter mode (such as CTR,
GCM, or CCM).

The implementation of `crypto.createDecipher()` derives keys using the OpenSSL
function [`EVP_BytesToKey`][] with the digest algorithm set to MD5, one
iteration, and no salt. The lack of salt allows dictionary attacks as the same
password always creates the same key. The low iteration count and
non-cryptographically secure hash algorithm allow passwords to be tested very
rapidly.

In line with OpenSSL's recommendation to use a more modern algorithm instead of
[`EVP_BytesToKey`][] it is recommended that developers derive a key and IV on
their own using [`crypto.scrypt()`][] and to use [`crypto.createDecipheriv()`][]
to create the `Decipher` object.

### `crypto.createDecipheriv(algorithm, key, iv[, options])`



* `algorithm` {string}
* `key` {string|ArrayBuffer|Buffer|TypedArray|DataView|KeyObject|CryptoKey}
* `iv` {string|ArrayBuffer|Buffer|TypedArray|DataView|null}
* `options` {Object} [`stream.transform` options][]
* Returns: {Decipher}

Creates and returns a `Decipher` object that uses the given `algorithm`, `key`
and initialization vector (`iv`).

The `options` argument controls stream behavior and is optional except when a
cipher in CCM or OCB mode (e.g. `'aes-128-ccm'`) is used. In that case, the
`authTagLength` option is required and specifies the length of the
authentication tag in bytes, see [CCM mode][]. In GCM mode, the `authTagLength`
option is not required but can be used to restrict accepted authentication tags
to those with the specified length.
For `chacha20-poly1305`, the `authTagLength` option defaults to 16 bytes.

The `algorithm` is dependent on OpenSSL, examples are `'aes192'`, etc. On
recent OpenSSL releases, `openssl list -cipher-algorithms` will
display the available cipher algorithms.

The `key` is the raw key used by the `algorithm` and `iv` is an
[initialization vector][]. Both arguments must be `'utf8'` encoded strings,
[Buffers][`Buffer`], `TypedArray`, or `DataView`s. The `key` may optionally be
a [`KeyObject`][] of type `secret`. If the cipher does not need
an initialization vector, `iv` may be `null`.

When passing strings for `key` or `iv`, please consider
[caveats when using strings as inputs to cryptographic APIs][].

Initialization vectors should be unpredictable and unique; ideally, they will be
cryptographically random. They do not have to be secret: IVs are typically just
added to ciphertext messages unencrypted. It may sound contradictory that
something has to be unpredictable and unique, but does not have to be secret;
remember that an attacker must not be able to predict ahead of time what a given
IV will be.

### `crypto.createDiffieHellman(prime[, primeEncoding][, generator][, generatorEncoding])`



* `prime` {string|ArrayBuffer|Buffer|TypedArray|DataView}
* `primeEncoding` {string} The [encoding][] of the `prime` string.
* `generator` {number|string|ArrayBuffer|Buffer|TypedArray|DataView}
  **Default:** `2`
* `generatorEncoding` {string} The [encoding][] of the `generator` string.
* Returns: {DiffieHellman}

Creates a `DiffieHellman` key exchange object using the supplied `prime` and an
optional specific `generator`.

The `generator` argument can be a number, string, or [`Buffer`][]. If
`generator` is not specified, the value `2` is used.

If `primeEncoding` is specified, `prime` is expected to be a string; otherwise
a [`Buffer`][], `TypedArray`, or `DataView` is expected.

If `generatorEncoding` is specified, `generator` is expected to be a string;
otherwise a number, [`Buffer`][], `TypedArray`, or `DataView` is expected.

### `crypto.createDiffieHellman(primeLength[, generator])`



* `primeLength` {number}
* `generator` {number} **Default:** `2`
* Returns: {DiffieHellman}

Creates a `DiffieHellman` key exchange object and generates a prime of
`primeLength` bits using an optional specific numeric `generator`.
If `generator` is not specified, the value `2` is used.

### `crypto.createDiffieHellmanGroup(name)`



* `name` {string}
* Returns: {DiffieHellmanGroup}

An alias for [`crypto.getDiffieHellman()`][]

### `crypto.createECDH(curveName)`



* `curveName` {string}
* Returns: {ECDH}

Creates an Elliptic Curve Diffie-Hellman (`ECDH`) key exchange object using a
predefined curve specified by the `curveName` string. Use
[`crypto.getCurves()`][] to obtain a list of available curve names. On recent
OpenSSL releases, `openssl ecparam -list_curves` will also display the name
and description of each available elliptic curve.

### `crypto.createHash(algorithm[, options])`



* `algorithm` {string}
* `options` {Object} [`stream.transform` options][]
* Returns: {Hash}

Creates and returns a `Hash` object that can be used to generate hash digests
using the given `algorithm`. Optional `options` argument controls stream
behavior. For XOF hash functions such as `'shake256'`, the `outputLength` option
can be used to specify the desired output length in bytes.

The `algorithm` is dependent on the available algorithms supported by the
version of OpenSSL on the platform. Examples are `'sha256'`, `'sha512'`, etc.
On recent releases of OpenSSL, `openssl list -digest-algorithms` will
display the available digest algorithms.

Example: generating the sha256 sum of a file

```mjs
import {
  createReadStream,
} from 'node:fs';
import { argv } from 'node:process';
const {
  createHash,
} = await import('node:crypto');

const filename = argv[2];

const hash = createHash('sha256');

const input = createReadStream(filename);
input.on('readable', () => {
  // Only one element is going to be produced by the
  // hash stream.
  const data = input.read();
  if (data)
    hash.update(data);
  else {
    console.log(`${hash.digest('hex')} ${filename}`);
  }
});
```

```cjs
const {
  createReadStream,
} = require('node:fs');
const {
  createHash,
} = require('node:crypto');
const { argv } = require('node:process');

const filename = argv[2];

const hash = createHash('sha256');

const input = createReadStream(filename);
input.on('readable', () => {
  // Only one element is going to be produced by the
  // hash stream.
  const data = input.read();
  if (data)
    hash.update(data);
  else {
    console.log(`${hash.digest('hex')} ${filename}`);
  }
});
```

### `crypto.createHmac(algorithm, key[, options])`



* `algorithm` {string}
* `key` {string|ArrayBuffer|Buffer|TypedArray|DataView|KeyObject|CryptoKey}
* `options` {Object} [`stream.transform` options][]
  * `encoding` {string} The string encoding to use when `key` is a string.
* Returns: {Hmac}

Creates and returns an `Hmac` object that uses the given `algorithm` and `key`.
Optional `options` argument controls stream behavior.

The `algorithm` is dependent on the available algorithms supported by the
version of OpenSSL on the platform. Examples are `'sha256'`, `'sha512'`, etc.
On recent releases of OpenSSL, `openssl list -digest-algorithms` will
display the available digest algorithms.

The `key` is the HMAC key used to generate the cryptographic HMAC hash. If it is
a [`KeyObject`][], its type must be `secret`. If it is a string, please consider
[caveats when using strings as inputs to cryptographic APIs][]. If it was
obtained from a cryptographically secure source of entropy, such as
[`crypto.randomBytes()`][] or [`crypto.generateKey()`][], its length should not
exceed the block size of `algorithm` (e.g., 512 bits for SHA-256).

Example: generating the sha256 HMAC of a file

```mjs
import {
  createReadStream,
} from 'node:fs';
import { argv } from 'node:process';
const {
  createHmac,
} = await import('node:crypto');

const filename = argv[2];

const hmac = createHmac('sha256', 'a secret');

const input = createReadStream(filename);
input.on('readable', () => {
  // Only one element is going to be produced by the
  // hash stream.
  const data = input.read();
  if (data)
    hmac.update(data);
  else {
    console.log(`${hmac.digest('hex')} ${filename}`);
  }
});
```

```cjs
const {
  createReadStream,
} = require('node:fs');
const {
  createHmac,
} = require('node:crypto');
const { argv } = require('node:process');

const filename = argv[2];

const hmac = createHmac('sha256', 'a secret');

const input = createReadStream(filename);
input.on('readable', () => {
  // Only one element is going to be produced by the
  // hash stream.
  const data = input.read();
  if (data)
    hmac.update(data);
  else {
    console.log(`${hmac.digest('hex')} ${filename}`);
  }
});
```

### `crypto.createPrivateKey(key)`





* `key` {Object|string|ArrayBuffer|Buffer|TypedArray|DataView}
  * `key`: {string|ArrayBuffer|Buffer|TypedArray|DataView|Object} The key
    material, either in PEM, DER, or JWK format.
  * `format`: {string} Must be `'pem'`, `'der'`, or '`'jwk'`.
    **Default:** `'pem'`.
  * `type`: {string} Must be `'pkcs1'`, `'pkcs8'` or `'sec1'`. This option is
    required only if the `format` is `'der'` and ignored otherwise.
  * `passphrase`: {string | Buffer} The passphrase to use for decryption.
  * `encoding`: {string} The string encoding to use when `key` is a string.
* Returns: {KeyObject}



Creates and returns a new key object containing a private key. If `key` is a
string or `Buffer`, `format` is assumed to be `'pem'`; otherwise, `key`
must be an object with the properties described above.

If the private key is encrypted, a `passphrase` must be specified. The length
of the passphrase is limited to 1024 bytes.

### `crypto.createPublicKey(key)`





* `key` {Object|string|ArrayBuffer|Buffer|TypedArray|DataView}
  * `key`: {string|ArrayBuffer|Buffer|TypedArray|DataView|Object} The key
    material, either in PEM, DER, or JWK format.
  * `format`: {string} Must be `'pem'`, `'der'`, or `'jwk'`.
    **Default:** `'pem'`.
  * `type`: {string} Must be `'pkcs1'` or `'spki'`. This option is
    required only if the `format` is `'der'` and ignored otherwise.
  * `encoding` {string} The string encoding to use when `key` is a string.
* Returns: {KeyObject}



Creates and returns a new key object containing a public key. If `key` is a
string or `Buffer`, `format` is assumed to be `'pem'`; if `key` is a `KeyObject`
with type `'private'`, the public key is derived from the given private key;
otherwise, `key` must be an object with the properties described above.

If the format is `'pem'`, the `'key'` may also be an X.509 certificate.

Because public keys can be derived from private keys, a private key may be
passed instead of a public key. In that case, this function behaves as if
[`crypto.createPrivateKey()`][] had been called, except that the type of the
returned `KeyObject` will be `'public'` and that the private key cannot be
extracted from the returned `KeyObject`. Similarly, if a `KeyObject` with type
`'private'` is given, a new `KeyObject` with type `'public'` will be returned
and it will be impossible to extract the private key from the returned object.

### `crypto.createSecretKey(key[, encoding])`



* `key` {string|ArrayBuffer|Buffer|TypedArray|DataView}
* `encoding` {string} The string encoding when `key` is a string.
* Returns: {KeyObject}

Creates and returns a new key object containing a secret key for symmetric
encryption or `Hmac`.

### `crypto.createSign(algorithm[, options])`



* `algorithm` {string}
* `options` {Object} [`stream.Writable` options][]
* Returns: {Sign}

Creates and returns a `Sign` object that uses the given `algorithm`. Use
[`crypto.getHashes()`][] to obtain the names of the available digest algorithms.
Optional `options` argument controls the `stream.Writable` behavior.

In some cases, a `Sign` instance can be created using the name of a signature
algorithm, such as `'RSA-SHA256'`, instead of a digest algorithm. This will use
the corresponding digest algorithm. This does not work for all signature
algorithms, such as `'ecdsa-with-SHA256'`, so it is best to always use digest
algorithm names.

### `crypto.createVerify(algorithm[, options])`



* `algorithm` {string}
* `options` {Object} [`stream.Writable` options][]
* Returns: {Verify}

Creates and returns a `Verify` object that uses the given algorithm.
Use [`crypto.getHashes()`][] to obtain an array of names of the available
signing algorithms. Optional `options` argument controls the
`stream.Writable` behavior.

In some cases, a `Verify` instance can be created using the name of a signature
algorithm, such as `'RSA-SHA256'`, instead of a digest algorithm. This will use
the corresponding digest algorithm. This does not work for all signature
algorithms, such as `'ecdsa-with-SHA256'`, so it is best to always use digest
algorithm names.

### `crypto.diffieHellman(options)`



* `options`: {Object}
  * `privateKey`: {KeyObject}
  * `publicKey`: {KeyObject}
* Returns: {Buffer}

Computes the Diffie-Hellman secret based on a `privateKey` and a `publicKey`.
Both keys must have the same `asymmetricKeyType`, which must be one of `'dh'`
(for Diffie-Hellman), `'ec'` (for ECDH), `'x448'`, or `'x25519'` (for ECDH-ES).

### `crypto.generateKey(type, options, callback)`



* `type`: {string} The intended use of the generated secret key. Currently
  accepted values are `'hmac'` and `'aes'`.
* `options`: {Object}
  * `length`: {number} The bit length of the key to generate. This must be a
    value greater than 0.
    * If `type` is `'hmac'`, the minimum is 8, and the maximum length is
      231-1. If the value is not a multiple of 8, the generated
      key will be truncated to `Math.floor(length / 8)`.
    * If `type` is `'aes'`, the length must be one of `128`, `192`, or `256`.
* `callback`: {Function}
  * `err`: {Error}
  * `key`: {KeyObject}

Asynchronously generates a new random secret key of the given `length`. The
`type` will determine which validations will be performed on the `length`.

```mjs
const {
  generateKey,
} = await import('node:crypto');

generateKey('hmac', { length: 512 }, (err, key) => {
  if (err) throw err;
  console.log(key.export().toString('hex'));  // 46e..........620
});
```

```cjs
const {
  generateKey,
} = require('node:crypto');

generateKey('hmac', { length: 512 }, (err, key) => {
  if (err) throw err;
  console.log(key.export().toString('hex'));  // 46e..........620
});
```

The size of a generated HMAC key should not exceed the block size of the
underlying hash function. See [`crypto.createHmac()`][] for more information.

### `crypto.generateKeyPair(type, options, callback)`



* `type`: {string} Must be `'rsa'`, `'rsa-pss'`, `'dsa'`, `'ec'`, `'ed25519'`,
  `'ed448'`, `'x25519'`, `'x448'`, or `'dh'`.
* `options`: {Object}
  * `modulusLength`: {number} Key size in bits (RSA, DSA).
  * `publicExponent`: {number} Public exponent (RSA). **Default:** `0x10001`.
  * `hashAlgorithm`: {string} Name of the message digest (RSA-PSS).
  * `mgf1HashAlgorithm`: {string} Name of the message digest used by
    MGF1 (RSA-PSS).
  * `saltLength`: {number} Minimal salt length in bytes (RSA-PSS).
  * `divisorLength`: {number} Size of `q` in bits (DSA).
  * `namedCurve`: {string} Name of the curve to use (EC).
  * `prime`: {Buffer} The prime parameter (DH).
  * `primeLength`: {number} Prime length in bits (DH).
  * `generator`: {number} Custom generator (DH). **Default:** `2`.
  * `groupName`: {string} Diffie-Hellman group name (DH). See
    [`crypto.getDiffieHellman()`][].
  * `paramEncoding`: {string} Must be `'named'` or `'explicit'` (EC).
    **Default:** `'named'`.
  * `publicKeyEncoding`: {Object} See [`keyObject.export()`][].
  * `privateKeyEncoding`: {Object} See [`keyObject.export()`][].
* `callback`: {Function}
  * `err`: {Error}
  * `publicKey`: {string | Buffer | KeyObject}
  * `privateKey`: {string | Buffer | KeyObject}

Generates a new asymmetric key pair of the given `type`. RSA, RSA-PSS, DSA, EC,
Ed25519, Ed448, X25519, X448, and DH are currently supported.

If a `publicKeyEncoding` or `privateKeyEncoding` was specified, this function
behaves as if [`keyObject.export()`][] had been called on its result. Otherwise,
the respective part of the key is returned as a [`KeyObject`][].

It is recommended to encode public keys as `'spki'` and private keys as
`'pkcs8'` with encryption for long-term storage:

```mjs
const {
  generateKeyPair,
} = await import('node:crypto');

generateKeyPair('rsa', {
  modulusLength: 4096,
  publicKeyEncoding: {
    type: 'spki',
    format: 'pem',
  },
  privateKeyEncoding: {
    type: 'pkcs8',
    format: 'pem',
    cipher: 'aes-256-cbc',
    passphrase: 'top secret',
  },
}, (err, publicKey, privateKey) => {
  // Handle errors and use the generated key pair.
});
```

```cjs
const {
  generateKeyPair,
} = require('node:crypto');

generateKeyPair('rsa', {
  modulusLength: 4096,
  publicKeyEncoding: {
    type: 'spki',
    format: 'pem',
  },
  privateKeyEncoding: {
    type: 'pkcs8',
    format: 'pem',
    cipher: 'aes-256-cbc',
    passphrase: 'top secret',
  },
}, (err, publicKey, privateKey) => {
  // Handle errors and use the generated key pair.
});
```

On completion, `callback` will be called with `err` set to `undefined` and
`publicKey` / `privateKey` representing the generated key pair.

If this method is invoked as its [`util.promisify()`][]ed version, it returns
a `Promise` for an `Object` with `publicKey` and `privateKey` properties.

### `crypto.generateKeyPairSync(type, options)`



* `type`: {string} Must be `'rsa'`, `'rsa-pss'`, `'dsa'`, `'ec'`, `'ed25519'`,
  `'ed448'`, `'x25519'`, `'x448'`, or `'dh'`.
* `options`: {Object}
  * `modulusLength`: {number} Key size in bits (RSA, DSA).
  * `publicExponent`: {number} Public exponent (RSA). **Default:** `0x10001`.
  * `hashAlgorithm`: {string} Name of the message digest (RSA-PSS).
  * `mgf1HashAlgorithm`: {string} Name of the message digest used by
    MGF1 (RSA-PSS).
  * `saltLength`: {number} Minimal salt length in bytes (RSA-PSS).
  * `divisorLength`: {number} Size of `q` in bits (DSA).
  * `namedCurve`: {string} Name of the curve to use (EC).
  * `prime`: {Buffer} The prime parameter (DH).
  * `primeLength`: {number} Prime length in bits (DH).
  * `generator`: {number} Custom generator (DH). **Default:** `2`.
  * `groupName`: {string} Diffie-Hellman group name (DH). See
    [`crypto.getDiffieHellman()`][].
  * `paramEncoding`: {string} Must be `'named'` or `'explicit'` (EC).
    **Default:** `'named'`.
  * `publicKeyEncoding`: {Object} See [`keyObject.export()`][].
  * `privateKeyEncoding`: {Object} See [`keyObject.export()`][].
* Returns: {Object}
  * `publicKey`: {string | Buffer | KeyObject}
  * `privateKey`: {string | Buffer | KeyObject}

Generates a new asymmetric key pair of the given `type`. RSA, RSA-PSS, DSA, EC,
Ed25519, Ed448, X25519, X448, and DH are currently supported.

If a `publicKeyEncoding` or `privateKeyEncoding` was specified, this function
behaves as if [`keyObject.export()`][] had been called on its result. Otherwise,
the respective part of the key is returned as a [`KeyObject`][].

When encoding public keys, it is recommended to use `'spki'`. When encoding
private keys, it is recommended to use `'pkcs8'` with a strong passphrase,
and to keep the passphrase confidential.

```mjs
const {
  generateKeyPairSync,
} = await import('node:crypto');

const {
  publicKey,
  privateKey,
} = generateKeyPairSync('rsa', {
  modulusLength: 4096,
  publicKeyEncoding: {
    type: 'spki',
    format: 'pem',
  },
  privateKeyEncoding: {
    type: 'pkcs8',
    format: 'pem',
    cipher: 'aes-256-cbc',
    passphrase: 'top secret',
  },
});
```

```cjs
const {
  generateKeyPairSync,
} = require('node:crypto');

const {
  publicKey,
  privateKey,
} = generateKeyPairSync('rsa', {
  modulusLength: 4096,
  publicKeyEncoding: {
    type: 'spki',
    format: 'pem',
  },
  privateKeyEncoding: {
    type: 'pkcs8',
    format: 'pem',
    cipher: 'aes-256-cbc',
    passphrase: 'top secret',
  },
});
```

The return value `{ publicKey, privateKey }` represents the generated key pair.
When PEM encoding was selected, the respective key will be a string, otherwise
it will be a buffer containing the data encoded as DER.

### `crypto.generateKeySync(type, options)`



* `type`: {string} The intended use of the generated secret key. Currently
  accepted values are `'hmac'` and `'aes'`.
* `options`: {Object}
  * `length`: {number} The bit length of the key to generate.
    * If `type` is `'hmac'`, the minimum is 8, and the maximum length is
      231-1. If the value is not a multiple of 8, the generated
      key will be truncated to `Math.floor(length / 8)`.
    * If `type` is `'aes'`, the length must be one of `128`, `192`, or `256`.
* Returns: {KeyObject}

Synchronously generates a new random secret key of the given `length`. The
`type` will determine which validations will be performed on the `length`.

```mjs
const {
  generateKeySync,
} = await import('node:crypto');

const key = generateKeySync('hmac', { length: 512 });
console.log(key.export().toString('hex'));  // e89..........41e
```

```cjs
const {
  generateKeySync,
} = require('node:crypto');

const key = generateKeySync('hmac', { length: 512 });
console.log(key.export().toString('hex'));  // e89..........41e
```

The size of a generated HMAC key should not exceed the block size of the
underlying hash function. See [`crypto.createHmac()`][] for more information.

### `crypto.generatePrime(size[, options[, callback]])`



* `size` {number} The size (in bits) of the prime to generate.
* `options` {Object}
  * `add` {ArrayBuffer|SharedArrayBuffer|TypedArray|Buffer|DataView|bigint}
  * `rem` {ArrayBuffer|SharedArrayBuffer|TypedArray|Buffer|DataView|bigint}
  * `safe` {boolean} **Default:** `false`.
  * `bigint` {boolean} When `true`, the generated prime is returned
    as a `bigint`.
* `callback` {Function}
  * `err` {Error}
  * `prime` {ArrayBuffer|bigint}

Generates a pseudorandom prime of `size` bits.

If `options.safe` is `true`, the prime will be a safe prime -- that is,
`(prime - 1) / 2` will also be a prime.

The `options.add` and `options.rem` parameters can be used to enforce additional
requirements, e.g., for Diffie-Hellman:

* If `options.add` and `options.rem` are both set, the prime will satisfy the
  condition that `prime % add = rem`.
* If only `options.add` is set and `options.safe` is not `true`, the prime will
  satisfy the condition that `prime % add = 1`.
* If only `options.add` is set and `options.safe` is set to `true`, the prime
  will instead satisfy the condition that `prime % add = 3`. This is necessary
  because `prime % add = 1` for `options.add > 2` would contradict the condition
  enforced by `options.safe`.
* `options.rem` is ignored if `options.add` is not given.

Both `options.add` and `options.rem` must be encoded as big-endian sequences
if given as an `ArrayBuffer`, `SharedArrayBuffer`, `TypedArray`, `Buffer`, or
`DataView`.

By default, the prime is encoded as a big-endian sequence of octets
in an {ArrayBuffer}. If the `bigint` option is `true`, then a {bigint}
is provided.

### `crypto.generatePrimeSync(size[, options])`



* `size` {number} The size (in bits) of the prime to generate.
* `options` {Object}
  * `add` {ArrayBuffer|SharedArrayBuffer|TypedArray|Buffer|DataView|bigint}
  * `rem` {ArrayBuffer|SharedArrayBuffer|TypedArray|Buffer|DataView|bigint}
  * `safe` {boolean} **Default:** `false`.
  * `bigint` {boolean} When `true`, the generated prime is returned
    as a `bigint`.
* Returns: {ArrayBuffer|bigint}

Generates a pseudorandom prime of `size` bits.

If `options.safe` is `true`, the prime will be a safe prime -- that is,
`(prime - 1) / 2` will also be a prime.

The `options.add` and `options.rem` parameters can be used to enforce additional
requirements, e.g., for Diffie-Hellman:

* If `options.add` and `options.rem` are both set, the prime will satisfy the
  condition that `prime % add = rem`.
* If only `options.add` is set and `options.safe` is not `true`, the prime will
  satisfy the condition that `prime % add = 1`.
* If only `options.add` is set and `options.safe` is set to `true`, the prime
  will instead satisfy the condition that `prime % add = 3`. This is necessary
  because `prime % add = 1` for `options.add > 2` would contradict the condition
  enforced by `options.safe`.
* `options.rem` is ignored if `options.add` is not given.

Both `options.add` and `options.rem` must be encoded as big-endian sequences
if given as an `ArrayBuffer`, `SharedArrayBuffer`, `TypedArray`, `Buffer`, or
`DataView`.

By default, the prime is encoded as a big-endian sequence of octets
in an {ArrayBuffer}. If the `bigint` option is `true`, then a {bigint}
is provided.

### `crypto.getCipherInfo(nameOrNid[, options])`



* `nameOrNid`: {string|number} The name or nid of the cipher to query.
* `options`: {Object}
  * `keyLength`: {number} A test key length.
  * `ivLength`: {number} A test IV length.
* Returns: {Object}
  * `name` {string} The name of the cipher
  * `nid` {number} The nid of the cipher
  * `blockSize` {number} The block size of the cipher in bytes. This property
    is omitted when `mode` is `'stream'`.
  * `ivLength` {number} The expected or default initialization vector length in
    bytes. This property is omitted if the cipher does not use an initialization
    vector.
  * `keyLength` {number} The expected or default key length in bytes.
  * `mode` {string} The cipher mode. One of `'cbc'`, `'ccm'`, `'cfb'`, `'ctr'`,
    `'ecb'`, `'gcm'`, `'ocb'`, `'ofb'`, `'stream'`, `'wrap'`, `'xts'`.

Returns information about a given cipher.

Some ciphers accept variable length keys and initialization vectors. By default,
the `crypto.getCipherInfo()` method will return the default values for these
ciphers. To test if a given key length or iv length is acceptable for given
cipher, use the `keyLength` and `ivLength` options. If the given values are
unacceptable, `undefined` will be returned.

### `crypto.getCiphers()`



* Returns: {string\[]} An array with the names of the supported cipher
  algorithms.

```mjs
const {
  getCiphers,
} = await import('node:crypto');

console.log(getCiphers()); // ['aes-128-cbc', 'aes-128-ccm', ...]
```

```cjs
const {
  getCiphers,
} = require('node:crypto');

console.log(getCiphers()); // ['aes-128-cbc', 'aes-128-ccm', ...]
```

### `crypto.getCurves()`



* Returns: {string\[]} An array with the names of the supported elliptic curves.

```mjs
const {
  getCurves,
} = await import('node:crypto');

console.log(getCurves()); // ['Oakley-EC2N-3', 'Oakley-EC2N-4', ...]
```

```cjs
const {
  getCurves,
} = require('node:crypto');

console.log(getCurves()); // ['Oakley-EC2N-3', 'Oakley-EC2N-4', ...]
```

### `crypto.getDiffieHellman(groupName)`



* `groupName` {string}
* Returns: {DiffieHellmanGroup}

Creates a predefined `DiffieHellmanGroup` key exchange object. The
supported groups are listed in the documentation for [`DiffieHellmanGroup`][].

The returned object mimics the interface of objects created by
[`crypto.createDiffieHellman()`][], but will not allow changing
the keys (with [`diffieHellman.setPublicKey()`][], for example). The
advantage of using this method is that the parties do not have to
generate nor exchange a group modulus beforehand, saving both processor
and communication time.

Example (obtaining a shared secret):

```mjs
const {
  getDiffieHellman,
} = await import('node:crypto');
const alice = getDiffieHellman('modp14');
const bob = getDiffieHellman('modp14');

alice.generateKeys();
bob.generateKeys();

const aliceSecret = alice.computeSecret(bob.getPublicKey(), null, 'hex');
const bobSecret = bob.computeSecret(alice.getPublicKey(), null, 'hex');

/* aliceSecret and bobSecret should be the same */
console.log(aliceSecret === bobSecret);
```

```cjs
const {
  getDiffieHellman,
} = require('node:crypto');

const alice = getDiffieHellman('modp14');
const bob = getDiffieHellman('modp14');

alice.generateKeys();
bob.generateKeys();

const aliceSecret = alice.computeSecret(bob.getPublicKey(), null, 'hex');
const bobSecret = bob.computeSecret(alice.getPublicKey(), null, 'hex');

/* aliceSecret and bobSecret should be the same */
console.log(aliceSecret === bobSecret);
```

### `crypto.getFips()`



* Returns: {number} `1` if and only if a FIPS compliant crypto provider is
  currently in use, `0` otherwise. A future semver-major release may change
  the return type of this API to a {boolean}.

### `crypto.getHashes()`



* Returns: {string\[]} An array of the names of the supported hash algorithms,
  such as `'RSA-SHA256'`. Hash algorithms are also called "digest" algorithms.

```mjs
const {
  getHashes,
} = await import('node:crypto');

console.log(getHashes()); // ['DSA', 'DSA-SHA', 'DSA-SHA1', ...]
```

```cjs
const {
  getHashes,
} = require('node:crypto');

console.log(getHashes()); // ['DSA', 'DSA-SHA', 'DSA-SHA1', ...]
```

### `crypto.getRandomValues(typedArray)`



* `typedArray` {Buffer|TypedArray|DataView|ArrayBuffer}
* Returns: {Buffer|TypedArray|DataView|ArrayBuffer} Returns `typedArray`.

A convenient alias for [`crypto.webcrypto.getRandomValues()`][]. This
implementation is not compliant with the Web Crypto spec, to write
web-compatible code use [`crypto.webcrypto.getRandomValues()`][] instead.

### `crypto.hkdf(digest, ikm, salt, info, keylen, callback)`



* `digest` {string} The digest algorithm to use.
* `ikm` {string|ArrayBuffer|Buffer|TypedArray|DataView|KeyObject} The input
  keying material. Must be provided but can be zero-length.
* `salt` {string|ArrayBuffer|Buffer|TypedArray|DataView} The salt value. Must
  be provided but can be zero-length.
* `info` {string|ArrayBuffer|Buffer|TypedArray|DataView} Additional info value.
  Must be provided but can be zero-length, and cannot be more than 1024 bytes.
* `keylen` {number} The length of the key to generate. Must be greater than 0.
  The maximum allowable value is `255` times the number of bytes produced by
  the selected digest function (e.g. `sha512` generates 64-byte hashes, making
  the maximum HKDF output 16320 bytes).
* `callback` {Function}
  * `err` {Error}
  * `derivedKey` {ArrayBuffer}

HKDF is a simple key derivation function defined in RFC 5869. The given `ikm`,
`salt` and `info` are used with the `digest` to derive a key of `keylen` bytes.

The supplied `callback` function is called with two arguments: `err` and
`derivedKey`. If an errors occurs while deriving the key, `err` will be set;
otherwise `err` will be `null`. The successfully generated `derivedKey` will
be passed to the callback as an {ArrayBuffer}. An error will be thrown if any
of the input arguments specify invalid values or types.

```mjs
import { Buffer } from 'node:buffer';
const {
  hkdf,
} = await import('node:crypto');

hkdf('sha512', 'key', 'salt', 'info', 64, (err, derivedKey) => {
  if (err) throw err;
  console.log(Buffer.from(derivedKey).toString('hex'));  // '24156e2...5391653'
});
```

```cjs
const {
  hkdf,
} = require('node:crypto');
const { Buffer } = require('node:buffer');

hkdf('sha512', 'key', 'salt', 'info', 64, (err, derivedKey) => {
  if (err) throw err;
  console.log(Buffer.from(derivedKey).toString('hex'));  // '24156e2...5391653'
});
```

### `crypto.hkdfSync(digest, ikm, salt, info, keylen)`



* `digest` {string} The digest algorithm to use.
* `ikm` {string|ArrayBuffer|Buffer|TypedArray|DataView|KeyObject} The input
  keying material. Must be provided but can be zero-length.
* `salt` {string|ArrayBuffer|Buffer|TypedArray|DataView} The salt value. Must
  be provided but can be zero-length.
* `info` {string|ArrayBuffer|Buffer|TypedArray|DataView} Additional info value.
  Must be provided but can be zero-length, and cannot be more than 1024 bytes.
* `keylen` {number} The length of the key to generate. Must be greater than 0.
  The maximum allowable value is `255` times the number of bytes produced by
  the selected digest function (e.g. `sha512` generates 64-byte hashes, making
  the maximum HKDF output 16320 bytes).
* Returns: {ArrayBuffer}

Provides a synchronous HKDF key derivation function as defined in RFC 5869. The
given `ikm`, `salt` and `info` are used with the `digest` to derive a key of
`keylen` bytes.

The successfully generated `derivedKey` will be returned as an {ArrayBuffer}.

An error will be thrown if any of the input arguments specify invalid values or
types, or if the derived key cannot be generated.

```mjs
import { Buffer } from 'node:buffer';
const {
  hkdfSync,
} = await import('node:crypto');

const derivedKey = hkdfSync('sha512', 'key', 'salt', 'info', 64);
console.log(Buffer.from(derivedKey).toString('hex'));  // '24156e2...5391653'
```

```cjs
const {
  hkdfSync,
} = require('node:crypto');
const { Buffer } = require('node:buffer');

const derivedKey = hkdfSync('sha512', 'key', 'salt', 'info', 64);
console.log(Buffer.from(derivedKey).toString('hex'));  // '24156e2...5391653'
```

### `crypto.pbkdf2(password, salt, iterations, keylen, digest, callback)`



* `password` {string|ArrayBuffer|Buffer|TypedArray|DataView}
* `salt` {string|ArrayBuffer|Buffer|TypedArray|DataView}
* `iterations` {number}
* `keylen` {number}
* `digest` {string}
* `callback` {Function}
  * `err` {Error}
  * `derivedKey` {Buffer}

Provides an asynchronous Password-Based Key Derivation Function 2 (PBKDF2)
implementation. A selected HMAC digest algorithm specified by `digest` is
applied to derive a key of the requested byte length (`keylen`) from the
`password`, `salt` and `iterations`.

The supplied `callback` function is called with two arguments: `err` and
`derivedKey`. If an error occurs while deriving the key, `err` will be set;
otherwise `err` will be `null`. By default, the successfully generated
`derivedKey` will be passed to the callback as a [`Buffer`][]. An error will be
thrown if any of the input arguments specify invalid values or types.

The `iterations` argument must be a number set as high as possible. The
higher the number of iterations, the more secure the derived key will be,
but will take a longer amount of time to complete.

The `salt` should be as unique as possible. It is recommended that a salt is
random and at least 16 bytes long. See [NIST SP 800-132][] for details.

When passing strings for `password` or `salt`, please consider
[caveats when using strings as inputs to cryptographic APIs][].

```mjs
const {
  pbkdf2,
} = await import('node:crypto');

pbkdf2('secret', 'salt', 100000, 64, 'sha512', (err, derivedKey) => {
  if (err) throw err;
  console.log(derivedKey.toString('hex'));  // '3745e48...08d59ae'
});
```

```cjs
const {
  pbkdf2,
} = require('node:crypto');

pbkdf2('secret', 'salt', 100000, 64, 'sha512', (err, derivedKey) => {
  if (err) throw err;
  console.log(derivedKey.toString('hex'));  // '3745e48...08d59ae'
});
```

An array of supported digest functions can be retrieved using
[`crypto.getHashes()`][].

This API uses libuv's threadpool, which can have surprising and
negative performance implications for some applications; see the
[`UV_THREADPOOL_SIZE`][] documentation for more information.

### `crypto.pbkdf2Sync(password, salt, iterations, keylen, digest)`



* `password` {string|Buffer|TypedArray|DataView}
* `salt` {string|Buffer|TypedArray|DataView}
* `iterations` {number}
* `keylen` {number}
* `digest` {string}
* Returns: {Buffer}

Provides a synchronous Password-Based Key Derivation Function 2 (PBKDF2)
implementation. A selected HMAC digest algorithm specified by `digest` is
applied to derive a key of the requested byte length (`keylen`) from the
`password`, `salt` and `iterations`.

If an error occurs an `Error` will be thrown, otherwise the derived key will be
returned as a [`Buffer`][].

The `iterations` argument must be a number set as high as possible. The
higher the number of iterations, the more secure the derived key will be,
but will take a longer amount of time to complete.

The `salt` should be as unique as possible. It is recommended that a salt is
random and at least 16 bytes long. See [NIST SP 800-132][] for details.

When passing strings for `password` or `salt`, please consider
[caveats when using strings as inputs to cryptographic APIs][].

```mjs
const {
  pbkdf2Sync,
} = await import('node:crypto');

const key = pbkdf2Sync('secret', 'salt', 100000, 64, 'sha512');
console.log(key.toString('hex'));  // '3745e48...08d59ae'
```

```cjs
const {
  pbkdf2Sync,
} = require('node:crypto');

const key = pbkdf2Sync('secret', 'salt', 100000, 64, 'sha512');
console.log(key.toString('hex'));  // '3745e48...08d59ae'
```

An array of supported digest functions can be retrieved using
[`crypto.getHashes()`][].

### `crypto.privateDecrypt(privateKey, buffer)`





* `privateKey` {Object|string|ArrayBuffer|Buffer|TypedArray|DataView|KeyObject|CryptoKey}
  * `oaepHash` {string} The hash function to use for OAEP padding and MGF1.
    **Default:** `'sha1'`
  * `oaepLabel` {string|ArrayBuffer|Buffer|TypedArray|DataView} The label to
    use for OAEP padding. If not specified, no label is used.
  * `padding` {crypto.constants} An optional padding value defined in
    `crypto.constants`, which may be: `crypto.constants.RSA_NO_PADDING`,
    `crypto.constants.RSA_PKCS1_PADDING`, or
    `crypto.constants.RSA_PKCS1_OAEP_PADDING`.
* `buffer` {string|ArrayBuffer|Buffer|TypedArray|DataView}
* Returns: {Buffer} A new `Buffer` with the decrypted content.



Decrypts `buffer` with `privateKey`. `buffer` was previously encrypted using
the corresponding public key, for example using [`crypto.publicEncrypt()`][].

If `privateKey` is not a [`KeyObject`][], this function behaves as if
`privateKey` had been passed to [`crypto.createPrivateKey()`][]. If it is an
object, the `padding` property can be passed. Otherwise, this function uses
`RSA_PKCS1_OAEP_PADDING`.

### `crypto.privateEncrypt(privateKey, buffer)`





* `privateKey` {Object|string|ArrayBuffer|Buffer|TypedArray|DataView|KeyObject|CryptoKey}
  * `key` {string|ArrayBuffer|Buffer|TypedArray|DataView|KeyObject|CryptoKey}
    A PEM encoded private key.
  * `passphrase` {string|ArrayBuffer|Buffer|TypedArray|DataView} An optional
    passphrase for the private key.
  * `padding` {crypto.constants} An optional padding value defined in
    `crypto.constants`, which may be: `crypto.constants.RSA_NO_PADDING` or
    `crypto.constants.RSA_PKCS1_PADDING`.
  * `encoding` {string} The string encoding to use when `buffer`, `key`,
    or `passphrase` are strings.
* `buffer` {string|ArrayBuffer|Buffer|TypedArray|DataView}
* Returns: {Buffer} A new `Buffer` with the encrypted content.



Encrypts `buffer` with `privateKey`. The returned data can be decrypted using
the corresponding public key, for example using [`crypto.publicDecrypt()`][].

If `privateKey` is not a [`KeyObject`][], this function behaves as if
`privateKey` had been passed to [`crypto.createPrivateKey()`][]. If it is an
object, the `padding` property can be passed. Otherwise, this function uses
`RSA_PKCS1_PADDING`.

### `crypto.publicDecrypt(key, buffer)`





* `key` {Object|string|ArrayBuffer|Buffer|TypedArray|DataView|KeyObject|CryptoKey}
  * `passphrase` {string|ArrayBuffer|Buffer|TypedArray|DataView} An optional
    passphrase for the private key.
  * `padding` {crypto.constants} An optional padding value defined in
    `crypto.constants`, which may be: `crypto.constants.RSA_NO_PADDING` or
    `crypto.constants.RSA_PKCS1_PADDING`.
  * `encoding` {string} The string encoding to use when `buffer`, `key`,
    or `passphrase` are strings.
* `buffer` {string|ArrayBuffer|Buffer|TypedArray|DataView}
* Returns: {Buffer} A new `Buffer` with the decrypted content.



Decrypts `buffer` with `key`.`buffer` was previously encrypted using
the corresponding private key, for example using [`crypto.privateEncrypt()`][].

If `key` is not a [`KeyObject`][], this function behaves as if
`key` had been passed to [`crypto.createPublicKey()`][]. If it is an
object, the `padding` property can be passed. Otherwise, this function uses
`RSA_PKCS1_PADDING`.

Because RSA public keys can be derived from private keys, a private key may
be passed instead of a public key.

### `crypto.publicEncrypt(key, buffer)`





* `key` {Object|string|ArrayBuffer|Buffer|TypedArray|DataView|KeyObject|CryptoKey}
  * `key` {string|ArrayBuffer|Buffer|TypedArray|DataView|KeyObject|CryptoKey}
    A PEM encoded public or private key, {KeyObject}, or {CryptoKey}.
  * `oaepHash` {string} The hash function to use for OAEP padding and MGF1.
    **Default:** `'sha1'`
  * `oaepLabel` {string|ArrayBuffer|Buffer|TypedArray|DataView} The label to
    use for OAEP padding. If not specified, no label is used.
  * `passphrase` {string|ArrayBuffer|Buffer|TypedArray|DataView} An optional
    passphrase for the private key.
  * `padding` {crypto.constants} An optional padding value defined in
    `crypto.constants`, which may be: `crypto.constants.RSA_NO_PADDING`,
    `crypto.constants.RSA_PKCS1_PADDING`, or
    `crypto.constants.RSA_PKCS1_OAEP_PADDING`.
  * `encoding` {string} The string encoding to use when `buffer`, `key`,
    `oaepLabel`, or `passphrase` are strings.
* `buffer` {string|ArrayBuffer|Buffer|TypedArray|DataView}
* Returns: {Buffer} A new `Buffer` with the encrypted content.



Encrypts the content of `buffer` with `key` and returns a new
[`Buffer`][] with encrypted content. The returned data can be decrypted using
the corresponding private key, for example using [`crypto.privateDecrypt()`][].

If `key` is not a [`KeyObject`][], this function behaves as if
`key` had been passed to [`crypto.createPublicKey()`][]. If it is an
object, the `padding` property can be passed. Otherwise, this function uses
`RSA_PKCS1_OAEP_PADDING`.

Because RSA public keys can be derived from private keys, a private key may
be passed instead of a public key.

### `crypto.randomBytes(size[, callback])`



* `size` {number} The number of bytes to generate.  The `size` must
  not be larger than `2**31 - 1`.
* `callback` {Function}
  * `err` {Error}
  * `buf` {Buffer}
* Returns: {Buffer} if the `callback` function is not provided.

Generates cryptographically strong pseudorandom data. The `size` argument
is a number indicating the number of bytes to generate.

If a `callback` function is provided, the bytes are generated asynchronously
and the `callback` function is invoked with two arguments: `err` and `buf`.
If an error occurs, `err` will be an `Error` object; otherwise it is `null`. The
`buf` argument is a [`Buffer`][] containing the generated bytes.

```mjs
// Asynchronous
const {
  randomBytes,
} = await import('node:crypto');

randomBytes(256, (err, buf) => {
  if (err) throw err;
  console.log(`${buf.length} bytes of random data: ${buf.toString('hex')}`);
});
```

```cjs
// Asynchronous
const {
  randomBytes,
} = require('node:crypto');

randomBytes(256, (err, buf) => {
  if (err) throw err;
  console.log(`${buf.length} bytes of random data: ${buf.toString('hex')}`);
});
```

If the `callback` function is not provided, the random bytes are generated
synchronously and returned as a [`Buffer`][]. An error will be thrown if
there is a problem generating the bytes.

```mjs
// Synchronous
const {
  randomBytes,
} = await import('node:crypto');

const buf = randomBytes(256);
console.log(
  `${buf.length} bytes of random data: ${buf.toString('hex')}`);
```

```cjs
// Synchronous
const {
  randomBytes,
} = require('node:crypto');

const buf = randomBytes(256);
console.log(
  `${buf.length} bytes of random data: ${buf.toString('hex')}`);
```

The `crypto.randomBytes()` method will not complete until there is
sufficient entropy available.
This should normally never take longer than a few milliseconds. The only time
when generating the random bytes may conceivably block for a longer period of
time is right after boot, when the whole system is still low on entropy.

This API uses libuv's threadpool, which can have surprising and
negative performance implications for some applications; see the
[`UV_THREADPOOL_SIZE`][] documentation for more information.

The asynchronous version of `crypto.randomBytes()` is carried out in a single
threadpool request. To minimize threadpool task length variation, partition
large `randomBytes` requests when doing so as part of fulfilling a client
request.

### `crypto.randomFillSync(buffer[, offset][, size])`



* `buffer` {ArrayBuffer|Buffer|TypedArray|DataView} Must be supplied. The
  size of the provided `buffer` must not be larger than `2**31 - 1`.
* `offset` {number} **Default:** `0`
* `size` {number} **Default:** `buffer.length - offset`. The `size` must
  not be larger than `2**31 - 1`.
* Returns: {ArrayBuffer|Buffer|TypedArray|DataView} The object passed as
  `buffer` argument.

Synchronous version of [`crypto.randomFill()`][].

```mjs
import { Buffer } from 'node:buffer';
const { randomFillSync } = await import('node:crypto');

const buf = Buffer.alloc(10);
console.log(randomFillSync(buf).toString('hex'));

randomFillSync(buf, 5);
console.log(buf.toString('hex'));

// The above is equivalent to the following:
randomFillSync(buf, 5, 5);
console.log(buf.toString('hex'));
```

```cjs
const { randomFillSync } = require('node:crypto');
const { Buffer } = require('node:buffer');

const buf = Buffer.alloc(10);
console.log(randomFillSync(buf).toString('hex'));

randomFillSync(buf, 5);
console.log(buf.toString('hex'));

// The above is equivalent to the following:
randomFillSync(buf, 5, 5);
console.log(buf.toString('hex'));
```

Any `ArrayBuffer`, `TypedArray` or `DataView` instance may be passed as
`buffer`.

```mjs
import { Buffer } from 'node:buffer';
const { randomFillSync } = await import('node:crypto');

const a = new Uint32Array(10);
console.log(Buffer.from(randomFillSync(a).buffer,
                        a.byteOffset, a.byteLength).toString('hex'));

const b = new DataView(new ArrayBuffer(10));
console.log(Buffer.from(randomFillSync(b).buffer,
                        b.byteOffset, b.byteLength).toString('hex'));

const c = new ArrayBuffer(10);
console.log(Buffer.from(randomFillSync(c)).toString('hex'));
```

```cjs
const { randomFillSync } = require('node:crypto');
const { Buffer } = require('node:buffer');

const a = new Uint32Array(10);
console.log(Buffer.from(randomFillSync(a).buffer,
                        a.byteOffset, a.byteLength).toString('hex'));

const b = new DataView(new ArrayBuffer(10));
console.log(Buffer.from(randomFillSync(b).buffer,
                        b.byteOffset, b.byteLength).toString('hex'));

const c = new ArrayBuffer(10);
console.log(Buffer.from(randomFillSync(c)).toString('hex'));
```

### `crypto.randomFill(buffer[, offset][, size], callback)`



* `buffer` {ArrayBuffer|Buffer|TypedArray|DataView} Must be supplied. The
  size of the provided `buffer` must not be larger than `2**31 - 1`.
* `offset` {number} **Default:** `0`
* `size` {number} **Default:** `buffer.length - offset`. The `size` must
  not be larger than `2**31 - 1`.
* `callback` {Function} `function(err, buf) {}`.

This function is similar to [`crypto.randomBytes()`][] but requires the first
argument to be a [`Buffer`][] that will be filled. It also
requires that a callback is passed in.

If the `callback` function is not provided, an error will be thrown.

```mjs
import { Buffer } from 'node:buffer';
const { randomFill } = await import('node:crypto');

const buf = Buffer.alloc(10);
randomFill(buf, (err, buf) => {
  if (err) throw err;
  console.log(buf.toString('hex'));
});

randomFill(buf, 5, (err, buf) => {
  if (err) throw err;
  console.log(buf.toString('hex'));
});

// The above is equivalent to the following:
randomFill(buf, 5, 5, (err, buf) => {
  if (err) throw err;
  console.log(buf.toString('hex'));
});
```

```cjs
const { randomFill } = require('node:crypto');
const { Buffer } = require('node:buffer');

const buf = Buffer.alloc(10);
randomFill(buf, (err, buf) => {
  if (err) throw err;
  console.log(buf.toString('hex'));
});

randomFill(buf, 5, (err, buf) => {
  if (err) throw err;
  console.log(buf.toString('hex'));
});

// The above is equivalent to the following:
randomFill(buf, 5, 5, (err, buf) => {
  if (err) throw err;
  console.log(buf.toString('hex'));
});
```

Any `ArrayBuffer`, `TypedArray`, or `DataView` instance may be passed as
`buffer`.

While this includes instances of `Float32Array` and `Float64Array`, this
function should not be used to generate random floating-point numbers. The
result may contain `+Infinity`, `-Infinity`, and `NaN`, and even if the array
contains finite numbers only, they are not drawn from a uniform random
distribution and have no meaningful lower or upper bounds.

```mjs
import { Buffer } from 'node:buffer';
const { randomFill } = await import('node:crypto');

const a = new Uint32Array(10);
randomFill(a, (err, buf) => {
  if (err) throw err;
  console.log(Buffer.from(buf.buffer, buf.byteOffset, buf.byteLength)
    .toString('hex'));
});

const b = new DataView(new ArrayBuffer(10));
randomFill(b, (err, buf) => {
  if (err) throw err;
  console.log(Buffer.from(buf.buffer, buf.byteOffset, buf.byteLength)
    .toString('hex'));
});

const c = new ArrayBuffer(10);
randomFill(c, (err, buf) => {
  if (err) throw err;
  console.log(Buffer.from(buf).toString('hex'));
});
```

```cjs
const { randomFill } = require('node:crypto');
const { Buffer } = require('node:buffer');

const a = new Uint32Array(10);
randomFill(a, (err, buf) => {
  if (err) throw err;
  console.log(Buffer.from(buf.buffer, buf.byteOffset, buf.byteLength)
    .toString('hex'));
});

const b = new DataView(new ArrayBuffer(10));
randomFill(b, (err, buf) => {
  if (err) throw err;
  console.log(Buffer.from(buf.buffer, buf.byteOffset, buf.byteLength)
    .toString('hex'));
});

const c = new ArrayBuffer(10);
randomFill(c, (err, buf) => {
  if (err) throw err;
  console.log(Buffer.from(buf).toString('hex'));
});
```

This API uses libuv's threadpool, which can have surprising and
negative performance implications for some applications; see the
[`UV_THREADPOOL_SIZE`][] documentation for more information.

The asynchronous version of `crypto.randomFill()` is carried out in a single
threadpool request. To minimize threadpool task length variation, partition
large `randomFill` requests when doing so as part of fulfilling a client
request.

### `crypto.randomInt([min, ]max[, callback])`



* `min` {integer} Start of random range (inclusive). **Default:** `0`.
* `max` {integer} End of random range (exclusive).
* `callback` {Function} `function(err, n) {}`.

Return a random integer `n` such that `min <= n < max`.  This
implementation avoids [modulo bias][].

The range (`max - min`) must be less than 248. `min` and `max` must
be [safe integers][].

If the `callback` function is not provided, the random integer is
generated synchronously.

```mjs
// Asynchronous
const {
  randomInt,
} = await import('node:crypto');

randomInt(3, (err, n) => {
  if (err) throw err;
  console.log(`Random number chosen from (0, 1, 2): ${n}`);
});
```

```cjs
// Asynchronous
const {
  randomInt,
} = require('node:crypto');

randomInt(3, (err, n) => {
  if (err) throw err;
  console.log(`Random number chosen from (0, 1, 2): ${n}`);
});
```

```mjs
// Synchronous
const {
  randomInt,
} = await import('node:crypto');

const n = randomInt(3);
console.log(`Random number chosen from (0, 1, 2): ${n}`);
```

```cjs
// Synchronous
const {
  randomInt,
} = require('node:crypto');

const n = randomInt(3);
console.log(`Random number chosen from (0, 1, 2): ${n}`);
```

```mjs
// With `min` argument
const {
  randomInt,
} = await import('node:crypto');

const n = randomInt(1, 7);
console.log(`The dice rolled: ${n}`);
```

```cjs
// With `min` argument
const {
  randomInt,
} = require('node:crypto');

const n = randomInt(1, 7);
console.log(`The dice rolled: ${n}`);
```

### `crypto.randomUUID([options])`



* `options` {Object}
  * `disableEntropyCache` {boolean} By default, to improve performance,
    Node.js generates and caches enough
    random data to generate up to 128 random UUIDs. To generate a UUID
    without using the cache, set `disableEntropyCache` to `true`.
    **Default:** `false`.
* Returns: {string}

Generates a random [RFC 4122][] version 4 UUID. The UUID is generated using a
cryptographic pseudorandom number generator.

### `crypto.scrypt(password, salt, keylen[, options], callback)`



* `password` {string|ArrayBuffer|Buffer|TypedArray|DataView}
* `salt` {string|ArrayBuffer|Buffer|TypedArray|DataView}
* `keylen` {number}
* `options` {Object}
  * `cost` {number} CPU/memory cost parameter. Must be a power of two greater
    than one. **Default:** `16384`.
  * `blockSize` {number} Block size parameter. **Default:** `8`.
  * `parallelization` {number} Parallelization parameter. **Default:** `1`.
  * `N` {number} Alias for `cost`. Only one of both may be specified.
  * `r` {number} Alias for `blockSize`. Only one of both may be specified.
  * `p` {number} Alias for `parallelization`. Only one of both may be specified.
  * `maxmem` {number} Memory upper bound. It is an error when (approximately)
    `128 * N * r > maxmem`. **Default:** `32 * 1024 * 1024`.
* `callback` {Function}
  * `err` {Error}
  * `derivedKey` {Buffer}

Provides an asynchronous [scrypt][] implementation. Scrypt is a password-based
key derivation function that is designed to be expensive computationally and
memory-wise in order to make brute-force attacks unrewarding.

The `salt` should be as unique as possible. It is recommended that a salt is
random and at least 16 bytes long. See [NIST SP 800-132][] for details.

When passing strings for `password` or `salt`, please consider
[caveats when using strings as inputs to cryptographic APIs][].

The `callback` function is called with two arguments: `err` and `derivedKey`.
`err` is an exception object when key derivation fails, otherwise `err` is
`null`. `derivedKey` is passed to the callback as a [`Buffer`][].

An exception is thrown when any of the input arguments specify invalid values
or types.

```mjs
const {
  scrypt,
} = await import('node:crypto');

// Using the factory defaults.
scrypt('password', 'salt', 64, (err, derivedKey) => {
  if (err) throw err;
  console.log(derivedKey.toString('hex'));  // '3745e48...08d59ae'
});
// Using a custom N parameter. Must be a power of two.
scrypt('password', 'salt', 64, { N: 1024 }, (err, derivedKey) => {
  if (err) throw err;
  console.log(derivedKey.toString('hex'));  // '3745e48...aa39b34'
});
```

```cjs
const {
  scrypt,
} = require('node:crypto');

// Using the factory defaults.
scrypt('password', 'salt', 64, (err, derivedKey) => {
  if (err) throw err;
  console.log(derivedKey.toString('hex'));  // '3745e48...08d59ae'
});
// Using a custom N parameter. Must be a power of two.
scrypt('password', 'salt', 64, { N: 1024 }, (err, derivedKey) => {
  if (err) throw err;
  console.log(derivedKey.toString('hex'));  // '3745e48...aa39b34'
});
```

### `crypto.scryptSync(password, salt, keylen[, options])`



* `password` {string|Buffer|TypedArray|DataView}
* `salt` {string|Buffer|TypedArray|DataView}
* `keylen` {number}
* `options` {Object}
  * `cost` {number} CPU/memory cost parameter. Must be a power of two greater
    than one. **Default:** `16384`.
  * `blockSize` {number} Block size parameter. **Default:** `8`.
  * `parallelization` {number} Parallelization parameter. **Default:** `1`.
  * `N` {number} Alias for `cost`. Only one of both may be specified.
  * `r` {number} Alias for `blockSize`. Only one of both may be specified.
  * `p` {number} Alias for `parallelization`. Only one of both may be specified.
  * `maxmem` {number} Memory upper bound. It is an error when (approximately)
    `128 * N * r > maxmem`. **Default:** `32 * 1024 * 1024`.
* Returns: {Buffer}

Provides a synchronous [scrypt][] implementation. Scrypt is a password-based
key derivation function that is designed to be expensive computationally and
memory-wise in order to make brute-force attacks unrewarding.

The `salt` should be as unique as possible. It is recommended that a salt is
random and at least 16 bytes long. See [NIST SP 800-132][] for details.

When passing strings for `password` or `salt`, please consider
[caveats when using strings as inputs to cryptographic APIs][].

An exception is thrown when key derivation fails, otherwise the derived key is
returned as a [`Buffer`][].

An exception is thrown when any of the input arguments specify invalid values
or types.

```mjs
const {
  scryptSync,
} = await import('node:crypto');
// Using the factory defaults.

const key1 = scryptSync('password', 'salt', 64);
console.log(key1.toString('hex'));  // '3745e48...08d59ae'
// Using a custom N parameter. Must be a power of two.
const key2 = scryptSync('password', 'salt', 64, { N: 1024 });
console.log(key2.toString('hex'));  // '3745e48...aa39b34'
```

```cjs
const {
  scryptSync,
} = require('node:crypto');
// Using the factory defaults.

const key1 = scryptSync('password', 'salt', 64);
console.log(key1.toString('hex'));  // '3745e48...08d59ae'
// Using a custom N parameter. Must be a power of two.
const key2 = scryptSync('password', 'salt', 64, { N: 1024 });
console.log(key2.toString('hex'));  // '3745e48...aa39b34'
```

### `crypto.secureHeapUsed()`



* Returns: {Object}
  * `total` {number} The total allocated secure heap size as specified
    using the `--secure-heap=n` command-line flag.
  * `min` {number} The minimum allocation from the secure heap as
    specified using the `--secure-heap-min` command-line flag.
  * `used` {number} The total number of bytes currently allocated from
    the secure heap.
  * `utilization` {number} The calculated ratio of `used` to `total`
    allocated bytes.

### `crypto.setEngine(engine[, flags])`



* `engine` {string}
* `flags` {crypto.constants} **Default:** `crypto.constants.ENGINE_METHOD_ALL`

Load and set the `engine` for some or all OpenSSL functions (selected by flags).

`engine` could be either an id or a path to the engine's shared library.

The optional `flags` argument uses `ENGINE_METHOD_ALL` by default. The `flags`
is a bit field taking one of or a mix of the following flags (defined in
`crypto.constants`):

* `crypto.constants.ENGINE_METHOD_RSA`
* `crypto.constants.ENGINE_METHOD_DSA`
* `crypto.constants.ENGINE_METHOD_DH`
* `crypto.constants.ENGINE_METHOD_RAND`
* `crypto.constants.ENGINE_METHOD_EC`
* `crypto.constants.ENGINE_METHOD_CIPHERS`
* `crypto.constants.ENGINE_METHOD_DIGESTS`
* `crypto.constants.ENGINE_METHOD_PKEY_METHS`
* `crypto.constants.ENGINE_METHOD_PKEY_ASN1_METHS`
* `crypto.constants.ENGINE_METHOD_ALL`
* `crypto.constants.ENGINE_METHOD_NONE`

### `crypto.setFips(bool)`



* `bool` {boolean} `true` to enable FIPS mode.

Enables the FIPS compliant crypto provider in a FIPS-enabled Node.js build.
Throws an error if FIPS mode is not available.

### `crypto.sign(algorithm, data, key[, callback])`





* `algorithm` {string | null | undefined}
* `data` {ArrayBuffer|Buffer|TypedArray|DataView}
* `key` {Object|string|ArrayBuffer|Buffer|TypedArray|DataView|KeyObject|CryptoKey}
* `callback` {Function}
  * `err` {Error}
  * `signature` {Buffer}
* Returns: {Buffer} if the `callback` function is not provided.



Calculates and returns the signature for `data` using the given private key and
algorithm. If `algorithm` is `null` or `undefined`, then the algorithm is
dependent upon the key type (especially Ed25519 and Ed448).

If `key` is not a [`KeyObject`][], this function behaves as if `key` had been
passed to [`crypto.createPrivateKey()`][]. If it is an object, the following
additional properties can be passed:

* `dsaEncoding` {string} For DSA and ECDSA, this option specifies the
  format of the generated signature. It can be one of the following:
  * `'der'` (default): DER-encoded ASN.1 signature structure encoding `(r, s)`.
  * `'ieee-p1363'`: Signature format `r || s` as proposed in IEEE-P1363.
* `padding` {integer} Optional padding value for RSA, one of the following:

  * `crypto.constants.RSA_PKCS1_PADDING` (default)
  * `crypto.constants.RSA_PKCS1_PSS_PADDING`

  `RSA_PKCS1_PSS_PADDING` will use MGF1 with the same hash function
  used to sign the message as specified in section 3.1 of [RFC 4055][].
* `saltLength` {integer} Salt length for when padding is
  `RSA_PKCS1_PSS_PADDING`. The special value
  `crypto.constants.RSA_PSS_SALTLEN_DIGEST` sets the salt length to the digest
  size, `crypto.constants.RSA_PSS_SALTLEN_MAX_SIGN` (default) sets it to the
  maximum permissible value.

If the `callback` function is provided this function uses libuv's threadpool.

### `crypto.subtle`



* Type: {SubtleCrypto}

A convenient alias for [`crypto.webcrypto.subtle`][].

### `crypto.timingSafeEqual(a, b)`



* `a` {ArrayBuffer|Buffer|TypedArray|DataView}
* `b` {ArrayBuffer|Buffer|TypedArray|DataView}
* Returns: {boolean}

This function compares the underlying bytes that represent the given
`ArrayBuffer`, `TypedArray`, or `DataView` instances using a constant-time
algorithm.

This function does not leak timing information that
would allow an attacker to guess one of the values. This is suitable for
comparing HMAC digests or secret values like authentication cookies or
[capability urls](https://www.w3.org/TR/capability-urls/).

`a` and `b` must both be `Buffer`s, `TypedArray`s, or `DataView`s, and they
must have the same byte length. An error is thrown if `a` and `b` have
different byte lengths.

If at least one of `a` and `b` is a `TypedArray` with more than one byte per
entry, such as `Uint16Array`, the result will be computed using the platform
byte order.

When both of the inputs are `Float32Array`s or
`Float64Array`s, this function might return unexpected results due to IEEE 754
encoding of floating-point numbers. In particular, neither `x === y` nor
`Object.is(x, y)` implies that the byte representations of two floating-point
numbers `x` and `y` are equal.

Use of `crypto.timingSafeEqual` does not guarantee that the _surrounding_ code
is timing-safe. Care should be taken to ensure that the surrounding code does
not introduce timing vulnerabilities.

### `crypto.verify(algorithm, data, key, signature[, callback])`





* `algorithm` {string|null|undefined}
* `data` {ArrayBuffer| Buffer|TypedArray|DataView}
* `key` {Object|string|ArrayBuffer|Buffer|TypedArray|DataView|KeyObject|CryptoKey}
* `signature` {ArrayBuffer|Buffer|TypedArray|DataView}
* `callback` {Function}
  * `err` {Error}
  * `result` {boolean}
* Returns: {boolean} `true` or `false` depending on the validity of the
  signature for the data and public key if the `callback` function is not
  provided.



Verifies the given signature for `data` using the given key and algorithm. If
`algorithm` is `null` or `undefined`, then the algorithm is dependent upon the
key type (especially Ed25519 and Ed448).

If `key` is not a [`KeyObject`][], this function behaves as if `key` had been
passed to [`crypto.createPublicKey()`][]. If it is an object, the following
additional properties can be passed:

* `dsaEncoding` {string} For DSA and ECDSA, this option specifies the
  format of the signature. It can be one of the following:
  * `'der'` (default): DER-encoded ASN.1 signature structure encoding `(r, s)`.
  * `'ieee-p1363'`: Signature format `r || s` as proposed in IEEE-P1363.
* `padding` {integer} Optional padding value for RSA, one of the following:

  * `crypto.constants.RSA_PKCS1_PADDING` (default)
  * `crypto.constants.RSA_PKCS1_PSS_PADDING`

  `RSA_PKCS1_PSS_PADDING` will use MGF1 with the same hash function
  used to sign the message as specified in section 3.1 of [RFC 4055][].
* `saltLength` {integer} Salt length for when padding is
  `RSA_PKCS1_PSS_PADDING`. The special value
  `crypto.constants.RSA_PSS_SALTLEN_DIGEST` sets the salt length to the digest
  size, `crypto.constants.RSA_PSS_SALTLEN_MAX_SIGN` (default) sets it to the
  maximum permissible value.

The `signature` argument is the previously calculated signature for the `data`.

Because public keys can be derived from private keys, a private key or a public
key may be passed for `key`.

If the `callback` function is provided this function uses libuv's threadpool.

### `crypto.webcrypto`



Type: {Crypto} An implementation of the Web Crypto API standard.

See the [Web Crypto API documentation][] for details.

## Notes

### Using strings as inputs to cryptographic APIs

For historical reasons, many cryptographic APIs provided by Node.js accept
strings as inputs where the underlying cryptographic algorithm works on byte
sequences. These instances include plaintexts, ciphertexts, symmetric keys,
initialization vectors, passphrases, salts, authentication tags,
and additional authenticated data.

When passing strings to cryptographic APIs, consider the following factors.

* Not all byte sequences are valid UTF-8 strings. Therefore, when a byte
  sequence of length `n` is derived from a string, its entropy is generally
  lower than the entropy of a random or pseudorandom `n` byte sequence.
  For example, no UTF-8 string will result in the byte sequence `c0 af`. Secret
  keys should almost exclusively be random or pseudorandom byte sequences.
* Similarly, when converting random or pseudorandom byte sequences to UTF-8
  strings, subsequences that do not represent valid code points may be replaced
  by the Unicode replacement character (`U+FFFD`). The byte representation of
  the resulting Unicode string may, therefore, not be equal to the byte sequence
  that the string was created from.

  ```js
  const original = [0xc0, 0xaf];
  const bytesAsString = Buffer.from(original).toString('utf8');
  const stringAsBytes = Buffer.from(bytesAsString, 'utf8');
  console.log(stringAsBytes);
  // Prints '<Buffer ef bf bd ef bf bd>'.
  ```

  The outputs of ciphers, hash functions, signature algorithms, and key
  derivation functions are pseudorandom byte sequences and should not be
  used as Unicode strings.
* When strings are obtained from user input, some Unicode characters can be
  represented in multiple equivalent ways that result in different byte
  sequences. For example, when passing a user passphrase to a key derivation
  function, such as PBKDF2 or scrypt, the result of the key derivation function
  depends on whether the string uses composed or decomposed characters. Node.js
  does not normalize character representations. Developers should consider using
  [`String.prototype.normalize()`][] on user inputs before passing them to
  cryptographic APIs.

### Legacy streams API (prior to Node.js 0.10)

The Crypto module was added to Node.js before there was the concept of a
unified Stream API, and before there were [`Buffer`][] objects for handling
binary data. As such, many `crypto` classes have methods not
typically found on other Node.js classes that implement the [streams][stream]
API (e.g. `update()`, `final()`, or `digest()`). Also, many methods accepted
and returned `'latin1'` encoded strings by default rather than `Buffer`s. This
default was changed after Node.js v0.8 to use [`Buffer`][] objects by default
instead.

### Support for weak or compromised algorithms

The `node:crypto` module still supports some algorithms which are already
compromised and are not recommended for use. The API also allows
the use of ciphers and hashes with a small key size that are too weak for safe
use.

Users should take full responsibility for selecting the crypto
algorithm and key size according to their security requirements.

Based on the recommendations of [NIST SP 800-131A][]:

* MD5 and SHA-1 are no longer acceptable where collision resistance is
  required such as digital signatures.
* The key used with RSA, DSA, and DH algorithms is recommended to have
  at least 2048 bits and that of the curve of ECDSA and ECDH at least
  224 bits, to be safe to use for several years.
* The DH groups of `modp1`, `modp2` and `modp5` have a key size
  smaller than 2048 bits and are not recommended.

See the reference for other recommendations and details.

Some algorithms that have known weaknesses and are of little relevance in
practice are only available through the [legacy provider][], which is not
enabled by default.

### CCM mode

CCM is one of the supported [AEAD algorithms][]. Applications which use this
mode must adhere to certain restrictions when using the cipher API:

* The authentication tag length must be specified during cipher creation by
  setting the `authTagLength` option and must be one of 4, 6, 8, 10, 12, 14 or
  16 bytes.
* The length of the initialization vector (nonce) `N` must be between 7 and 13
  bytes (`7 ≤ N ≤ 13`).
* The length of the plaintext is limited to `2 ** (8 * (15 - N))` bytes.
* When decrypting, the authentication tag must be set via `setAuthTag()` before
  calling `update()`.
  Otherwise, decryption will fail and `final()` will throw an error in
  compliance with section 2.6 of [RFC 3610][].
* Using stream methods such as `write(data)`, `end(data)` or `pipe()` in CCM
  mode might fail as CCM cannot handle more than one chunk of data per instance.
* When passing additional authenticated data (AAD), the length of the actual
  message in bytes must be passed to `setAAD()` via the `plaintextLength`
  option.
  Many crypto libraries include the authentication tag in the ciphertext,
  which means that they produce ciphertexts of the length
  `plaintextLength + authTagLength`. Node.js does not include the authentication
  tag, so the ciphertext length is always `plaintextLength`.
  This is not necessary if no AAD is used.
* As CCM processes the whole message at once, `update()` must be called exactly
  once.
* Even though calling `update()` is sufficient to encrypt/decrypt the message,
  applications _must_ call `final()` to compute or verify the
  authentication tag.

```mjs
import { Buffer } from 'node:buffer';
const {
  createCipheriv,
  createDecipheriv,
  randomBytes,
} = await import('node:crypto');

const key = 'keykeykeykeykeykeykeykey';
const nonce = randomBytes(12);

const aad = Buffer.from('0123456789', 'hex');

const cipher = createCipheriv('aes-192-ccm', key, nonce, {
  authTagLength: 16,
});
const plaintext = 'Hello world';
cipher.setAAD(aad, {
  plaintextLength: Buffer.byteLength(plaintext),
});
const ciphertext = cipher.update(plaintext, 'utf8');
cipher.final();
const tag = cipher.getAuthTag();

// Now transmit { ciphertext, nonce, tag }.

const decipher = createDecipheriv('aes-192-ccm', key, nonce, {
  authTagLength: 16,
});
decipher.setAuthTag(tag);
decipher.setAAD(aad, {
  plaintextLength: ciphertext.length,
});
const receivedPlaintext = decipher.update(ciphertext, null, 'utf8');

try {
  decipher.final();
} catch (err) {
  throw new Error('Authentication failed!', { cause: err });
}

console.log(receivedPlaintext);
```

```cjs
const { Buffer } = require('node:buffer');
const {
  createCipheriv,
  createDecipheriv,
  randomBytes,
} = require('node:crypto');

const key = 'keykeykeykeykeykeykeykey';
const nonce = randomBytes(12);

const aad = Buffer.from('0123456789', 'hex');

const cipher = createCipheriv('aes-192-ccm', key, nonce, {
  authTagLength: 16,
});
const plaintext = 'Hello world';
cipher.setAAD(aad, {
  plaintextLength: Buffer.byteLength(plaintext),
});
const ciphertext = cipher.update(plaintext, 'utf8');
cipher.final();
const tag = cipher.getAuthTag();

// Now transmit { ciphertext, nonce, tag }.

const decipher = createDecipheriv('aes-192-ccm', key, nonce, {
  authTagLength: 16,
});
decipher.setAuthTag(tag);
decipher.setAAD(aad, {
  plaintextLength: ciphertext.length,
});
const receivedPlaintext = decipher.update(ciphertext, null, 'utf8');

try {
  decipher.final();
} catch (err) {
  throw new Error('Authentication failed!', { cause: err });
}

console.log(receivedPlaintext);
```

### FIPS mode

When using OpenSSL 3, Node.js supports FIPS 140-2 when used with an appropriate
OpenSSL 3 provider, such as the [FIPS provider from OpenSSL 3][] which can be
installed by following the instructions in [OpenSSL's FIPS README file][].

For FIPS support in Node.js you will need:

* A correctly installed OpenSSL 3 FIPS provider.
* An OpenSSL 3 [FIPS module configuration file][].
* An OpenSSL 3 configuration file that references the FIPS module
  configuration file.

Node.js will need to be configured with an OpenSSL configuration file that
points to the FIPS provider. An example configuration file looks like this:

```text
nodejs_conf = nodejs_init

.include /<absolute path>/fipsmodule.cnf

[nodejs_init]
providers = provider_sect

[provider_sect]
default = default_sect
# The fips section name should match the section name inside the
# included fipsmodule.cnf.
fips = fips_sect

[default_sect]
activate = 1
```

where `fipsmodule.cnf` is the FIPS module configuration file generated from the
FIPS provider installation step:

```bash
openssl fipsinstall
```

Set the `OPENSSL_CONF` environment variable to point to
your configuration file and `OPENSSL_MODULES` to the location of the FIPS
provider dynamic library. e.g.

```bash
export OPENSSL_CONF=/<path to configuration file>/nodejs.cnf
export OPENSSL_MODULES=/<path to openssl lib>/ossl-modules
```

FIPS mode can then be enabled in Node.js either by:

* Starting Node.js with `--enable-fips` or `--force-fips` command line flags.
* Programmatically calling `crypto.setFips(true)`.

Optionally FIPS mode can be enabled in Node.js via the OpenSSL configuration
file. e.g.

```text
nodejs_conf = nodejs_init

.include /<absolute path>/fipsmodule.cnf

[nodejs_init]
providers = provider_sect
alg_section = algorithm_sect

[provider_sect]
default = default_sect
# The fips section name should match the section name inside the
# included fipsmodule.cnf.
fips = fips_sect

[default_sect]
activate = 1

[algorithm_sect]
default_properties = fips=yes
```

## Crypto constants

The following constants exported by `crypto.constants` apply to various uses of
the `node:crypto`, `node:tls`, and `node:https` modules and are generally
specific to OpenSSL.

### OpenSSL options

See the [list of SSL OP Flags][] for details.

     Constant
     Description

     SSL_OP_ALL
     Applies multiple bug workarounds within OpenSSL. See
    https://www.openssl.org/docs/man3.0/man3/SSL_CTX_set_options.html
    for detail.

     SSL_OP_ALLOW_NO_DHE_KEX
     Instructs OpenSSL to allow a non-[EC]DHE-based key exchange mode
    for TLS v1.3

     SSL_OP_ALLOW_UNSAFE_LEGACY_RENEGOTIATION
     Allows legacy insecure renegotiation between OpenSSL and unpatched
    clients or servers. See
    https://www.openssl.org/docs/man3.0/man3/SSL_CTX_set_options.html.

     SSL_OP_CIPHER_SERVER_PREFERENCE
     Attempts to use the server's preferences instead of the client's when
    selecting a cipher. Behavior depends on protocol version. See
    https://www.openssl.org/docs/man3.0/man3/SSL_CTX_set_options.html.

     SSL_OP_CISCO_ANYCONNECT
     Instructs OpenSSL to use Cisco's "speshul" version of DTLS_BAD_VER.

     SSL_OP_COOKIE_EXCHANGE
     Instructs OpenSSL to turn on cookie exchange.

     SSL_OP_CRYPTOPRO_TLSEXT_BUG
     Instructs OpenSSL to add server-hello extension from an early version
    of the cryptopro draft.

     SSL_OP_DONT_INSERT_EMPTY_FRAGMENTS
     Instructs OpenSSL to disable a SSL 3.0/TLS 1.0 vulnerability
    workaround added in OpenSSL 0.9.6d.

     SSL_OP_LEGACY_SERVER_CONNECT
     Allows initial connection to servers that do not support RI.

     SSL_OP_NO_COMPRESSION
     Instructs OpenSSL to disable support for SSL/TLS compression.

     SSL_OP_NO_ENCRYPT_THEN_MAC
     Instructs OpenSSL to disable encrypt-then-MAC.

     SSL_OP_NO_QUERY_MTU

     SSL_OP_NO_RENEGOTIATION
     Instructs OpenSSL to disable renegotiation.

     SSL_OP_NO_SESSION_RESUMPTION_ON_RENEGOTIATION
     Instructs OpenSSL to always start a new session when performing
    renegotiation.

     SSL_OP_NO_SSLv2
     Instructs OpenSSL to turn off SSL v2

     SSL_OP_NO_SSLv3
     Instructs OpenSSL to turn off SSL v3

     SSL_OP_NO_TICKET
     Instructs OpenSSL to disable use of RFC4507bis tickets.

     SSL_OP_NO_TLSv1
     Instructs OpenSSL to turn off TLS v1

     SSL_OP_NO_TLSv1_1
     Instructs OpenSSL to turn off TLS v1.1

     SSL_OP_NO_TLSv1_2
     Instructs OpenSSL to turn off TLS v1.2

     SSL_OP_NO_TLSv1_3
     Instructs OpenSSL to turn off TLS v1.3

     SSL_OP_PRIORITIZE_CHACHA
     Instructs OpenSSL server to prioritize ChaCha20-Poly1305
    when the client does.
    This option has no effect if
    SSL_OP_CIPHER_SERVER_PREFERENCE
    is not enabled.

     SSL_OP_TLS_ROLLBACK_BUG
     Instructs OpenSSL to disable version rollback attack detection.

### OpenSSL engine constants

     Constant
     Description

     ENGINE_METHOD_RSA
     Limit engine usage to RSA

     ENGINE_METHOD_DSA
     Limit engine usage to DSA

     ENGINE_METHOD_DH
     Limit engine usage to DH

     ENGINE_METHOD_RAND
     Limit engine usage to RAND

     ENGINE_METHOD_EC
     Limit engine usage to EC

     ENGINE_METHOD_CIPHERS
     Limit engine usage to CIPHERS

     ENGINE_METHOD_DIGESTS
     Limit engine usage to DIGESTS

     ENGINE_METHOD_PKEY_METHS
     Limit engine usage to PKEY_METHDS

     ENGINE_METHOD_PKEY_ASN1_METHS
     Limit engine usage to PKEY_ASN1_METHS

     ENGINE_METHOD_ALL

     ENGINE_METHOD_NONE

### Other OpenSSL constants

     Constant
     Description

     DH_CHECK_P_NOT_SAFE_PRIME

     DH_CHECK_P_NOT_PRIME

     DH_UNABLE_TO_CHECK_GENERATOR

     DH_NOT_SUITABLE_GENERATOR

     ALPN_ENABLED

     RSA_PKCS1_PADDING

     RSA_SSLV23_PADDING

     RSA_NO_PADDING

     RSA_PKCS1_OAEP_PADDING

     RSA_X931_PADDING

     RSA_PKCS1_PSS_PADDING

     RSA_PSS_SALTLEN_DIGEST
     Sets the salt length for RSA_PKCS1_PSS_PADDING to the
        digest size when signing or verifying.

     RSA_PSS_SALTLEN_MAX_SIGN
     Sets the salt length for RSA_PKCS1_PSS_PADDING to the
        maximum permissible value when signing data.

     RSA_PSS_SALTLEN_AUTO
     Causes the salt length for RSA_PKCS1_PSS_PADDING to be
        determined automatically when verifying a signature.

     POINT_CONVERSION_COMPRESSED

     POINT_CONVERSION_UNCOMPRESSED

     POINT_CONVERSION_HYBRID

### Node.js crypto constants

     Constant
     Description

     defaultCoreCipherList
     Specifies the built-in default cipher list used by Node.js.

     defaultCipherList
     Specifies the active default cipher list used by the current Node.js
    process.

[AEAD algorithms]: https://en.wikipedia.org/wiki/Authenticated_encryption
[CCM mode]: #ccm-mode
[CVE-2021-44532]: https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2021-44532
[Caveats]: #support-for-weak-or-compromised-algorithms
[Crypto constants]: #crypto-constants
[FIPS module configuration file]: https://www.openssl.org/docs/man3.0/man5/fips_config.html
[FIPS provider from OpenSSL 3]: https://www.openssl.org/docs/man3.0/man7/crypto.html#FIPS-provider
[HTML 5.2]: https://www.w3.org/TR/html52/changes.html#features-removed
[JWK]: https://tools.ietf.org/html/rfc7517
[NIST SP 800-131A]: https://nvlpubs.nist.gov/nistpubs/SpecialPublications/NIST.SP.800-131Ar2.pdf
[NIST SP 800-132]: https://nvlpubs.nist.gov/nistpubs/Legacy/SP/nistspecialpublication800-132.pdf
[NIST SP 800-38D]: https://nvlpubs.nist.gov/nistpubs/Legacy/SP/nistspecialpublication800-38d.pdf
[Nonce-Disrespecting Adversaries]: https://github.com/nonce-disrespect/nonce-disrespect
[OpenSSL's FIPS README file]: https://github.com/openssl/openssl/blob/openssl-3.0/README-FIPS.md
[OpenSSL's SPKAC implementation]: https://www.openssl.org/docs/man3.0/man1/openssl-spkac.html
[RFC 1421]: https://www.rfc-editor.org/rfc/rfc1421.txt
[RFC 2409]: https://www.rfc-editor.org/rfc/rfc2409.txt
[RFC 2818]: https://www.rfc-editor.org/rfc/rfc2818.txt
[RFC 3526]: https://www.rfc-editor.org/rfc/rfc3526.txt
[RFC 3610]: https://www.rfc-editor.org/rfc/rfc3610.txt
[RFC 4055]: https://www.rfc-editor.org/rfc/rfc4055.txt
[RFC 4122]: https://www.rfc-editor.org/rfc/rfc4122.txt
[RFC 5208]: https://www.rfc-editor.org/rfc/rfc5208.txt
[RFC 5280]: https://www.rfc-editor.org/rfc/rfc5280.txt
[Web Crypto API documentation]: webcrypto.md
[`BN_is_prime_ex`]: https://www.openssl.org/docs/man1.1.1/man3/BN_is_prime_ex.html
[`Buffer`]: buffer.md
[`DH_generate_key()`]: https://www.openssl.org/docs/man3.0/man3/DH_generate_key.html
[`DiffieHellmanGroup`]: #class-diffiehellmangroup
[`EVP_BytesToKey`]: https://www.openssl.org/docs/man3.0/man3/EVP_BytesToKey.html
[`KeyObject`]: #class-keyobject
[`Sign`]: #class-sign
[`String.prototype.normalize()`]: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/String/normalize
[`UV_THREADPOOL_SIZE`]: cli.md#uv_threadpool_sizesize
[`Verify`]: #class-verify
[`cipher.final()`]: #cipherfinaloutputencoding
[`cipher.update()`]: #cipherupdatedata-inputencoding-outputencoding
[`crypto.createCipher()`]: #cryptocreatecipheralgorithm-password-options
[`crypto.createCipheriv()`]: #cryptocreatecipherivalgorithm-key-iv-options
[`crypto.createDecipher()`]: #cryptocreatedecipheralgorithm-password-options
[`crypto.createDecipheriv()`]: #cryptocreatedecipherivalgorithm-key-iv-options
[`crypto.createDiffieHellman()`]: #cryptocreatediffiehellmanprime-primeencoding-generator-generatorencoding
[`crypto.createECDH()`]: #cryptocreateecdhcurvename
[`crypto.createHash()`]: #cryptocreatehashalgorithm-options
[`crypto.createHmac()`]: #cryptocreatehmacalgorithm-key-options
[`crypto.createPrivateKey()`]: #cryptocreateprivatekeykey
[`crypto.createPublicKey()`]: #cryptocreatepublickeykey
[`crypto.createSecretKey()`]: #cryptocreatesecretkeykey-encoding
[`crypto.createSign()`]: #cryptocreatesignalgorithm-options
[`crypto.createVerify()`]: #cryptocreateverifyalgorithm-options
[`crypto.generateKey()`]: #cryptogeneratekeytype-options-callback
[`crypto.getCurves()`]: #cryptogetcurves
[`crypto.getDiffieHellman()`]: #cryptogetdiffiehellmangroupname
[`crypto.getHashes()`]: #cryptogethashes
[`crypto.privateDecrypt()`]: #cryptoprivatedecryptprivatekey-buffer
[`crypto.privateEncrypt()`]: #cryptoprivateencryptprivatekey-buffer
[`crypto.publicDecrypt()`]: #cryptopublicdecryptkey-buffer
[`crypto.publicEncrypt()`]: #cryptopublicencryptkey-buffer
[`crypto.randomBytes()`]: #cryptorandombytessize-callback
[`crypto.randomFill()`]: #cryptorandomfillbuffer-offset-size-callback
[`crypto.scrypt()`]: #cryptoscryptpassword-salt-keylen-options-callback
[`crypto.webcrypto.getRandomValues()`]: webcrypto.md#cryptogetrandomvaluestypedarray
[`crypto.webcrypto.subtle`]: webcrypto.md#class-subtlecrypto
[`decipher.final()`]: #decipherfinaloutputencoding
[`decipher.update()`]: #decipherupdatedata-inputencoding-outputencoding
[`diffieHellman.generateKeys()`]: #diffiehellmangeneratekeysencoding
[`diffieHellman.setPublicKey()`]: #diffiehellmansetpublickeypublickey-encoding
[`ecdh.generateKeys()`]: #ecdhgeneratekeysencoding-format
[`ecdh.setPrivateKey()`]: #ecdhsetprivatekeyprivatekey-encoding
[`hash.digest()`]: #hashdigestencoding
[`hash.update()`]: #hashupdatedata-inputencoding
[`hmac.digest()`]: #hmacdigestencoding
[`hmac.update()`]: #hmacupdatedata-inputencoding
[`import()`]: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Operators/import
[`keyObject.export()`]: #keyobjectexportoptions
[`postMessage()`]: worker_threads.md#portpostmessagevalue-transferlist
[`sign.sign()`]: #signsignprivatekey-outputencoding
[`sign.update()`]: #signupdatedata-inputencoding
[`stream.Writable` options]: stream.md#new-streamwritableoptions
[`stream.transform` options]: stream.md#new-streamtransformoptions
[`util.promisify()`]: util.md#utilpromisifyoriginal
[`verify.update()`]: #verifyupdatedata-inputencoding
[`verify.verify()`]: #verifyverifyobject-signature-signatureencoding
[`x509.fingerprint256`]: #x509fingerprint256
[caveats when using strings as inputs to cryptographic APIs]: #using-strings-as-inputs-to-cryptographic-apis
[certificate object]: tls.md#certificate-object
[encoding]: buffer.md#buffers-and-character-encodings
[initialization vector]: https://en.wikipedia.org/wiki/Initialization_vector
[legacy provider]: cli.md#--openssl-legacy-provider
[list of SSL OP Flags]: https://wiki.openssl.org/index.php/List_of_SSL_OP_Flags#Table_of_Options
[modulo bias]: https://en.wikipedia.org/wiki/Fisher%E2%80%93Yates_shuffle#Modulo_bias
[safe integers]: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Number/isSafeInteger
[scrypt]: https://en.wikipedia.org/wiki/Scrypt
[stream]: stream.md
[stream-writable-write]: stream.md#writablewritechunk-encoding-callback
