# Class Cipher

java.lang.Object
javax.crypto.Cipher

Direct Known Subclasses:
  `NullCipher`

public class Cipher extends Object
This class provides the functionality of a cryptographic cipher for encryption and decryption. It forms the core of the Java Cryptographic Extension (JCE) framework.

In order to create a `Cipher` object, the application calls the cipher's `getInstance` method, and passes the name of the requested transformation to it. Optionally, the name of a provider may be specified.

A transformation is a string that describes the operation (or set of operations) to be performed on the given input, to produce some output. A transformation always includes the name of a cryptographic algorithm (e.g., AES), and may be followed by a feedback mode and padding scheme.

A transformation is of the form:

- "algorithm/mode/padding" or
- "algorithm"

(in the latter case, provider-specific default values for the mode and padding scheme are used). For example, the following is a valid transformation:

         Cipher c = Cipher.getInstance("AES/CBC/PKCS5Padding");

Using modes such as `CFB` and `OFB`, block ciphers can encrypt data in units smaller than the cipher's actual block size. When requesting such a mode, you may optionally specify the number of bits to be processed at a time by appending this number to the mode name as shown in the "`AES/CFB8/NoPadding`" and "`AES/OFB32/PKCS5Padding`" transformations. If no such number is specified, a provider-specific default is used. (See the JDK Providers Documentation for the JDK Providers default values.) Thus, block ciphers can be turned into byte-oriented stream ciphers by using an 8 bit mode such as CFB8 or OFB8.

Modes such as Authenticated Encryption with Associated Data (AEAD) provide authenticity assurances for both confidential data and Additional Associated Data (AAD) that is not encrypted. (Please see RFC 5116 for more information on AEAD and AAD algorithms such as GCM/CCM.) Both confidential and AAD data can be used when calculating the authentication tag (similar to a `Mac`). This tag is appended to the ciphertext during encryption, and is verified on decryption.

AEAD modes such as GCM/CCM perform all AAD authenticity calculations before starting the ciphertext authenticity calculations. To avoid implementations having to internally buffer ciphertext, all AAD data must be supplied to GCM/CCM implementations (via the `updateAAD` methods) before the ciphertext is processed (via the `update` and `doFinal` methods).

Note that GCM mode has a uniqueness requirement on IVs used in encryption with a given key. When IVs are repeated for GCM encryption, such usages are subject to forgery attacks. Thus, after each encryption operation using GCM mode, callers should re-initialize the `Cipher` objects with GCM parameters which have a different IV value.

         GCMParameterSpec s = ...;
         cipher.init(..., s);

         // If the GCM parameters were generated by the provider, it can
         // be retrieved by:
         // cipher.getParameters().getParameterSpec(GCMParameterSpec.class);

         cipher.updateAAD(...);  // AAD
         cipher.update(...);     // Multi-part update
         cipher.doFinal(...);    // conclusion of operation

         // Use a different IV value for every encryption
         byte[] newIv = ...;
         s = new GCMParameterSpec(s.getTLen(), newIv);
         cipher.init(..., s);
         ...

The ChaCha20 and ChaCha20-Poly1305 algorithms have a similar requirement for unique nonces with a given key. After each encryption or decryption operation, callers should re-initialize their ChaCha20 or ChaCha20-Poly1305 ciphers with parameters that specify a different nonce value. Please see RFC 7539 for more information on the ChaCha20 and ChaCha20-Poly1305 algorithms.

Every implementation of the Java platform is required to support the following standard `Cipher` object transformations with the keysizes in parentheses:

- `AES/CBC/NoPadding` (128)
- `AES/CBC/PKCS5Padding` (128)
- `AES/ECB/NoPadding` (128)
- `AES/ECB/PKCS5Padding` (128)
- `AES/GCM/NoPadding` (128)
- `DESede/CBC/NoPadding` (168)
- `DESede/CBC/PKCS5Padding` (168)
- `DESede/ECB/NoPadding` (168)
- `DESede/ECB/PKCS5Padding` (168)
- `RSA/ECB/PKCS1Padding` (1024, 2048)
- `RSA/ECB/OAEPWithSHA-1AndMGF1Padding` (1024, 2048)
- `RSA/ECB/OAEPWithSHA-256AndMGF1Padding` (1024, 2048)

These transformations are described in the Cipher section of the Java Security Standard Algorithm Names Specification. Consult the release documentation for your implementation to see if any other transformations are supported.

Since:
  1.4
External Specifications
  - RFC 5116: An Interface and Algorithms for Authenticated Encryption
  - RFC 7539: ChaCha20 and Poly1305 for IETF Protocols
See Also:
  - `KeyGenerator`
  - `SecretKey`

## Field Summary

Fields
Modifier and Type
Field
Description
`static final int`
`DECRYPT_MODE`
Constant used to initialize cipher to decryption mode.
`static final int`
`ENCRYPT_MODE`
Constant used to initialize cipher to encryption mode.
`static final int`
`PRIVATE_KEY`
Constant used to indicate the to-be-unwrapped key is a "private key".
`static final int`
`PUBLIC_KEY`
Constant used to indicate the to-be-unwrapped key is a "public key".
`static final int`
`SECRET_KEY`
Constant used to indicate the to-be-unwrapped key is a "secret key".
`static final int`
`UNWRAP_MODE`
Constant used to initialize cipher to key-unwrapping mode.
`static final int`
`WRAP_MODE`
Constant used to initialize cipher to key-wrapping mode.

## Constructor Summary

Constructors
Modifier
Constructor
Description
`protected`
`Cipher(CipherSpi cipherSpi, Provider provider, String transformation)`
Creates a `Cipher` object.

## Method Summary

Modifier and Type
Method
Description
`final byte[]`
`doFinal()`
Finishes a multiple-part encryption or decryption operation, depending on how this `Cipher` object was initialized.
`final byte[]`
`doFinal(byte[] input)`
Encrypts or decrypts data in a single-part operation, or finishes a multiple-part operation.
`final int`
`doFinal(byte[] output, int outputOffset)`
Finishes a multiple-part encryption or decryption operation, depending on how this `Cipher` object was initialized.
`final byte[]`
`doFinal(byte[] input, int inputOffset, int inputLen)`
Encrypts or decrypts data in a single-part operation, or finishes a multiple-part operation.
`final int`
`doFinal(byte[] input, int inputOffset, int inputLen, byte[] output)`
Encrypts or decrypts data in a single-part operation, or finishes a multiple-part operation.
`final int`
`doFinal(byte[] input, int inputOffset, int inputLen, byte[] output, int outputOffset)`
Encrypts or decrypts data in a single-part operation, or finishes a multiple-part operation.
`final int`
`doFinal(ByteBuffer input, ByteBuffer output)`
Encrypts or decrypts data in a single-part operation, or finishes a multiple-part operation.
`final String`
`getAlgorithm()`
Returns the algorithm name of this `Cipher` object.
`final int`
`getBlockSize()`
Returns the block size (in bytes).
`final ExemptionMechanism`
`getExemptionMechanism()`
Returns the exemption mechanism object used with this `Cipher` object.
`static final Cipher`
`getInstance(String transformation)`
Returns a `Cipher` object that implements the specified transformation.
`static final Cipher`
`getInstance(String transformation, String provider)`
Returns a `Cipher` object that implements the specified transformation.
`static final Cipher`
`getInstance(String transformation, Provider provider)`
Returns a `Cipher` object that implements the specified transformation.
`final byte[]`
`getIV()`
Returns the initialization vector (IV) in a new buffer.
`static final int`
`getMaxAllowedKeyLength(String transformation)`
Returns the maximum key length for the specified transformation according to the installed JCE jurisdiction policy files.
`static final AlgorithmParameterSpec`
`getMaxAllowedParameterSpec(String transformation)`
Returns an {code AlgorithmParameterSpec} object which contains the maximum `Cipher` parameter value according to the jurisdiction policy file.
`final int`
`getOutputSize(int inputLen)`
Returns the length in bytes that an output buffer would need to be in order to hold the result of the next `update` or `doFinal` operation, given the input length `inputLen` (in bytes).
`final AlgorithmParameters`
`getParameters()`
Returns the parameters used with this `Cipher` object.
`final Provider`
`getProvider()`
Returns the provider of this `Cipher` object.
`final void`
`init(int opmode, Certificate certificate)`
Initializes this `Cipher` object with the public key from the given certificate.
`final void`
`init(int opmode, Certificate certificate, SecureRandom random)`
Initializes this `Cipher` object with the public key from the given certificate and a source of randomness.
`final void`
`init(int opmode, Key key)`
Initializes this `Cipher` object with a key.
`final void`
`init(int opmode, Key key, AlgorithmParameters params)`
Initializes this `Cipher` object with a key and a set of algorithm parameters.
`final void`
`init(int opmode, Key key, AlgorithmParameters params, SecureRandom random)`
Initializes this `Cipher` object with a key, a set of algorithm parameters, and a source of randomness.
`final void`
`init(int opmode, Key key, SecureRandom random)`
Initializes this `Cipher` object with a key and a source of randomness.
`final void`
`init(int opmode, Key key, AlgorithmParameterSpec params)`
Initializes this `Cipher` object with a key and a set of algorithm parameters.
`final void`
`init(int opmode, Key key, AlgorithmParameterSpec params, SecureRandom random)`
Initializes this `Cipher` object with a key, a set of algorithm parameters, and a source of randomness.
`String`
`toString()`
Returns a `String` representation of this `Cipher` object.
`final Key`
`unwrap(byte[] wrappedKey, String wrappedKeyAlgorithm, int wrappedKeyType)`
Unwrap a previously wrapped key.
`final byte[]`
`update(byte[] input)`
Continues a multiple-part encryption or decryption operation (depending on how this `Cipher` object was initialized), processing another data part.
`final byte[]`
`update(byte[] input, int inputOffset, int inputLen)`
Continues a multiple-part encryption or decryption operation (depending on how this `Cipher` object was initialized), processing another data part.
`final int`
`update(byte[] input, int inputOffset, int inputLen, byte[] output)`
Continues a multiple-part encryption or decryption operation (depending on how this `Cipher` object was initialized), processing another data part.
`final int`
`update(byte[] input, int inputOffset, int inputLen, byte[] output, int outputOffset)`
Continues a multiple-part encryption or decryption operation (depending on how this `Cipher` object was initialized), processing another data part.
`final int`
`update(ByteBuffer input, ByteBuffer output)`
Continues a multiple-part encryption or decryption operation (depending on how this `Cipher` object was initialized), processing another data part.
`final void`
`updateAAD(byte[] src)`
Continues a multi-part update of the Additional Authentication Data (AAD).
`final void`
`updateAAD(byte[] src, int offset, int len)`
Continues a multi-part update of the Additional Authentication Data (AAD), using a subset of the provided buffer.
`final void`
`updateAAD(ByteBuffer src)`
Continues a multi-part update of the Additional Authentication Data (AAD).
`final byte[]`
`wrap(Key key)`
Wrap a key.

### Methods declared in class java.lang.Object

`clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait`

## Field Details

### ENCRYPT_MODE

public static final int ENCRYPT_MODE
Constant used to initialize cipher to encryption mode.

See Also:
  - Constant Field Values

### DECRYPT_MODE

public static final int DECRYPT_MODE
Constant used to initialize cipher to decryption mode.

See Also:
  - Constant Field Values

### WRAP_MODE

public static final int WRAP_MODE
Constant used to initialize cipher to key-wrapping mode.

See Also:
  - Constant Field Values

### UNWRAP_MODE

public static final int UNWRAP_MODE
Constant used to initialize cipher to key-unwrapping mode.

See Also:
  - Constant Field Values

### PUBLIC_KEY

public static final int PUBLIC_KEY
Constant used to indicate the to-be-unwrapped key is a "public key".

See Also:
  - Constant Field Values

### PRIVATE_KEY

public static final int PRIVATE_KEY
Constant used to indicate the to-be-unwrapped key is a "private key".

See Also:
  - Constant Field Values

### SECRET_KEY

public static final int SECRET_KEY
Constant used to indicate the to-be-unwrapped key is a "secret key".

See Also:
  - Constant Field Values

## Constructor Details

### Cipher

protected Cipher(CipherSpi cipherSpi, Provider provider, String transformation)
Creates a `Cipher` object.

Parameters:
  `cipherSpi` - the delegate
  `provider` - the provider
  `transformation` - the transformation
Throws:
  `NullPointerException` - if `provider` is `null`
  `IllegalArgumentException` - if the supplied arguments are deemed invalid for constructing the `Cipher` object

## Method Details

### getInstance

public static final Cipher getInstance(String transformation) throws NoSuchAlgorithmException, NoSuchPaddingException
Returns a `Cipher` object that implements the specified transformation.

This method traverses the list of registered security providers, starting with the most preferred provider. A new `Cipher` object encapsulating the `CipherSpi` implementation from the first provider that supports the specified algorithm is returned.

Note that the list of registered providers may be retrieved via the `Security.getProviders()` method.

API Note:
  It is recommended to use a transformation that fully specifies the algorithm, mode, and padding. By not doing so, the provider will use a default for the mode and padding which may not meet the security requirements of your application.
Implementation Note:
  The JDK Reference Implementation additionally uses the `jdk.security.provider.preferred` `Security` property to determine the preferred provider order for the specified algorithm. This may be different than the order of providers returned by `Security.getProviders()`. See also the Cipher Transformations section of the JDK Providers document for information on the transformation defaults used by JDK providers.
Parameters:
  `transformation` - the name of the transformation, e.g., AES/CBC/PKCS5Padding. See the Cipher section in the Java Security Standard Algorithm Names Specification for information about standard transformation names.
Returns:
  a `Cipher` object that implements the requested transformation
Throws:
  `NoSuchAlgorithmException` - if `transformation` is `null`, empty, in an invalid format, or if no provider supports a `CipherSpi` implementation for the specified algorithm
  `NoSuchPaddingException` - if `transformation` contains a padding scheme that is not available
See Also:
  - `Provider`

### getInstance

public static final Cipher getInstance(String transformation, String provider) throws NoSuchAlgorithmException, NoSuchProviderException, NoSuchPaddingException
Returns a `Cipher` object that implements the specified transformation.

A new `Cipher` object encapsulating the `CipherSpi` implementation from the specified provider is returned. The specified provider must be registered in the security provider list.

Note that the list of registered providers may be retrieved via the `Security.getProviders()` method.

API Note:
  It is recommended to use a transformation that fully specifies the algorithm, mode, and padding. By not doing so, the provider will use a default for the mode and padding which may not meet the security requirements of your application.
Implementation Note:
  See the Cipher Transformations section of the JDK Providers document for information on the transformation defaults used by JDK providers.
Parameters:
  `transformation` - the name of the transformation, e.g., AES/CBC/PKCS5Padding. See the Cipher section in the Java Security Standard Algorithm Names Specification for information about standard transformation names.
  `provider` - the name of the provider
Returns:
  a `Cipher` object that implements the requested transformation
Throws:
  `IllegalArgumentException` - if the `provider` is `null` or empty
  `NoSuchAlgorithmException` - if `transformation` is `null`, empty, in an invalid format, or if a `CipherSpi` implementation for the specified algorithm is not available from the specified provider
  `NoSuchPaddingException` - if `transformation` contains a padding scheme that is not available
  `NoSuchProviderException` - if the specified provider is not registered in the security provider list
See Also:
  - `Provider`

### getInstance

public static final Cipher getInstance(String transformation, Provider provider) throws NoSuchAlgorithmException, NoSuchPaddingException
Returns a `Cipher` object that implements the specified transformation.

A new `Cipher` object encapsulating the `CipherSpi` implementation from the specified `provider` object is returned. Note that the specified `provider` object does not have to be registered in the provider list.

API Note:
  It is recommended to use a transformation that fully specifies the algorithm, mode, and padding. By not doing so, the provider will use a default for the mode and padding which may not meet the security requirements of your application.
Implementation Note:
  See the Cipher Transformations section of the JDK Providers document for information on the transformation defaults used by JDK providers.
Parameters:
  `transformation` - the name of the transformation, e.g., AES/CBC/PKCS5Padding. See the Cipher section in the Java Security Standard Algorithm Names Specification for information about standard transformation names.
  `provider` - the provider
Returns:
  a `Cipher` object that implements the requested transformation
Throws:
  `IllegalArgumentException` - if the `provider` is `null`
  `NoSuchAlgorithmException` - if `transformation` is `null`, empty, in an invalid format, or if a `CipherSpi` implementation for the specified algorithm is not available from the specified `provider` object
  `NoSuchPaddingException` - if `transformation` contains a padding scheme that is not available
See Also:
  - `Provider`

### getProvider

public final Provider getProvider()
Returns the provider of this `Cipher` object.

Returns:
  the provider of this `Cipher` object

### getAlgorithm

public final String getAlgorithm()
Returns the algorithm name of this `Cipher` object.

This is the same name that was specified in one of the `getInstance` calls that created this `Cipher` object.

Returns:
  the algorithm name of this `Cipher` object

### getBlockSize

public final int getBlockSize()
Returns the block size (in bytes).

Returns:
  the block size (in bytes), or 0 if this cipher is not a block cipher

### getOutputSize

public final int getOutputSize(int inputLen)
Returns the length in bytes that an output buffer would need to be in order to hold the result of the next `update` or `doFinal` operation, given the input length `inputLen` (in bytes).

This call takes into account any unprocessed (buffered) data from a previous `update` call, padding, and AEAD tagging.

The actual output length of the next `update` or `doFinal` call may be smaller than the length returned by this method.

Parameters:
  `inputLen` - the input length (in bytes)
Returns:
  the required output buffer size (in bytes)
Throws:
  `IllegalStateException` - if this `Cipher` object is in a wrong state (e.g., has not yet been initialized)

### getIV

public final byte[] getIV()
Returns the initialization vector (IV) in a new buffer.

This is useful in the case where a random IV was created, or in the context of password-based encryption or decryption, where the IV is derived from a user-supplied password.

Returns:
  the initialization vector in a new buffer, or `null` if this cipher does not use an IV, or if the IV has not yet been set.

### getParameters

public final AlgorithmParameters getParameters()
Returns the parameters used with this `Cipher` object.

The returned parameters may be the same that were used to initialize this cipher, or may contain additional default or random parameter values used by the underlying cipher implementation. If the required parameters were not supplied and can be generated by the cipher, the generated parameters are returned. Otherwise, `null` is returned.

Returns:
  the parameters used with this cipher, or `null`

### getExemptionMechanism

public final ExemptionMechanism getExemptionMechanism()
Returns the exemption mechanism object used with this `Cipher` object.

Returns:
  the exemption mechanism object used with this `Cipher` object, or `null` if this `Cipher` object does not use any exemption mechanism.

### init

public final void init(int opmode, Key key) throws InvalidKeyException
Initializes this `Cipher` object with a key.

The `Cipher` object is initialized for one of the following four operations: encryption, decryption, key wrapping or key unwrapping, depending on the value of `opmode`.

If this cipher requires any algorithm parameters that cannot be derived from the given `key`, the underlying cipher implementation is supposed to generate the required parameters itself (using provider-specific default or random values) if it is being initialized for encryption or key wrapping, and raise an `InvalidKeyException` if it is being initialized for decryption or key unwrapping. The generated parameters can be retrieved using `getParameters` or `getIV` (if the parameter is an IV).

If this cipher requires algorithm parameters that cannot be derived from the input parameters, and there are no reasonable provider-specific default values, initialization will necessarily fail.

If this cipher (including its feedback or padding scheme) requires any random bytes (e.g., for parameter generation), it will get them using the `SecureRandom` implementation of the highest-priority installed provider as the source of randomness. (If none of the installed providers supply an implementation of SecureRandom, a system-provided source of randomness will be used.)

Note that when a `Cipher` object is initialized, it loses all previously-acquired state. In other words, initializing a `Cipher` object is equivalent to creating a new instance of that `Cipher` object and initializing it.

Parameters:
  `opmode` - the operation mode of this `Cipher` object (this is one of the following: `ENCRYPT_MODE`, `DECRYPT_MODE`, `WRAP_MODE` or `UNWRAP_MODE`)
  `key` - the key
Throws:
  `InvalidKeyException` - if the given key is inappropriate for initializing this cipher, or requires algorithm parameters that cannot be determined from the given key, or if the given key has a keysize that exceeds the maximum allowable keysize (as determined from the configured jurisdiction policy files)
  `UnsupportedOperationException` - if `opmode` is `WRAP_MODE` or `UNWRAP_MODE` but the mode is not implemented by the underlying `CipherSpi`
  `InvalidParameterException` - if `opmode` is not one of the recognized values

### init

public final void init(int opmode, Key key, SecureRandom random) throws InvalidKeyException
Initializes this `Cipher` object with a key and a source of randomness.

The `Cipher` object is initialized for one of the following four operations: encryption, decryption, key wrapping or key unwrapping, depending on the value of `opmode`.

If this cipher requires any algorithm parameters that cannot be derived from the given `key`, the underlying cipher implementation is supposed to generate the required parameters itself (using provider-specific default or random values) if it is being initialized for encryption or key wrapping, and raise an `InvalidKeyException` if it is being initialized for decryption or key unwrapping. The generated parameters can be retrieved using `getParameters` or `getIV` (if the parameter is an IV).

If this cipher requires algorithm parameters that cannot be derived from the input parameters, and there are no reasonable provider-specific default values, initialization will necessarily fail.

If this cipher (including its feedback or padding scheme) requires any random bytes (e.g., for parameter generation), it will get them from `random`.

Note that when a `Cipher` object is initialized, it loses all previously-acquired state. In other words, initializing a `Cipher` object is equivalent to creating a new instance of that `Cipher` object and initializing it.

Parameters:
  `opmode` - the operation mode of this `Cipher` object (this is one of the following: `ENCRYPT_MODE`, `DECRYPT_MODE`, `WRAP_MODE` or `UNWRAP_MODE`)
  `key` - the encryption key
  `random` - the source of randomness
Throws:
  `InvalidKeyException` - if the given key is inappropriate for initializing this cipher, or requires algorithm parameters that cannot be determined from the given key, or if the given key has a keysize that exceeds the maximum allowable keysize (as determined from the configured jurisdiction policy files)
  `UnsupportedOperationException` - if `opmode` is `WRAP_MODE` or `UNWRAP_MODE` but the mode is not implemented by the underlying `CipherSpi`
  `InvalidParameterException` - if `opmode` is not one of the recognized values

### init

public final void init(int opmode, Key key, AlgorithmParameterSpec params) throws InvalidKeyException, InvalidAlgorithmParameterException
Initializes this `Cipher` object with a key and a set of algorithm parameters.

The `Cipher` object is initialized for one of the following four operations: encryption, decryption, key wrapping or key unwrapping, depending on the value of `opmode`.

If this cipher requires any algorithm parameters and `params` is `null`, the underlying cipher implementation is supposed to generate the required parameters itself (using provider-specific default or random values) if it is being initialized for encryption or key wrapping, and raise an `InvalidAlgorithmParameterException` if it is being initialized for decryption or key unwrapping. The generated parameters can be retrieved using `getParameters` or `getIV` (if the parameter is an IV).

If this cipher requires algorithm parameters that cannot be derived from the input parameters, and there are no reasonable provider-specific default values, initialization will necessarily fail.

If this cipher (including its feedback or padding scheme) requires any random bytes (e.g., for parameter generation), it will get them using the `SecureRandom` implementation of the highest-priority installed provider as the source of randomness. (If none of the installed providers supply an implementation of SecureRandom, a system-provided source of randomness will be used.)

Note that when a `Cipher` object is initialized, it loses all previously-acquired state. In other words, initializing a `Cipher` object is equivalent to creating a new instance of that `Cipher` object and initializing it.

Parameters:
  `opmode` - the operation mode of this `Cipher` object (this is one of the following: `ENCRYPT_MODE`, `DECRYPT_MODE`, `WRAP_MODE` or `UNWRAP_MODE`)
  `key` - the encryption key
  `params` - the algorithm parameters
Throws:
  `InvalidKeyException` - if the given key is inappropriate for initializing this cipher, or its keysize exceeds the maximum allowable keysize (as determined from the configured jurisdiction policy files)
  `InvalidAlgorithmParameterException` - if the given algorithm parameters are inappropriate for this cipher, or this cipher requires algorithm parameters and `params` is `null`, or the given algorithm parameters imply a cryptographic strength that would exceed the legal limits (as determined from the configured jurisdiction policy files)
  `UnsupportedOperationException` - if `opmode` is `WRAP_MODE` or `UNWRAP_MODE` but the mode is not implemented by the underlying `CipherSpi`
  `InvalidParameterException` - if `opmode` is not one of the recognized values

### init

public final void init(int opmode, Key key, AlgorithmParameterSpec params, SecureRandom random) throws InvalidKeyException, InvalidAlgorithmParameterException
Initializes this `Cipher` object with a key, a set of algorithm parameters, and a source of randomness.

The `Cipher` object is initialized for one of the following four operations: encryption, decryption, key wrapping or key unwrapping, depending on the value of `opmode`.

If this cipher requires any algorithm parameters and `params` is `null`, the underlying cipher implementation is supposed to generate the required parameters itself (using provider-specific default or random values) if it is being initialized for encryption or key wrapping, and raise an `InvalidAlgorithmParameterException` if it is being initialized for decryption or key unwrapping. The generated parameters can be retrieved using `getParameters` or `getIV` (if the parameter is an IV).

If this cipher requires algorithm parameters that cannot be derived from the input parameters, and there are no reasonable provider-specific default values, initialization will necessarily fail.

If this cipher (including its feedback or padding scheme) requires any random bytes (e.g., for parameter generation), it will get them from `random`.

Note that when a `Cipher` object is initialized, it loses all previously-acquired state. In other words, initializing a `Cipher` object is equivalent to creating a new instance of that `Cipher` object and initializing it.

Parameters:
  `opmode` - the operation mode of this `Cipher` object (this is one of the following: `ENCRYPT_MODE`, `DECRYPT_MODE`, `WRAP_MODE` or `UNWRAP_MODE`)
  `key` - the encryption key
  `params` - the algorithm parameters
  `random` - the source of randomness
Throws:
  `InvalidKeyException` - if the given key is inappropriate for initializing this cipher, or its keysize exceeds the maximum allowable keysize (as determined from the configured jurisdiction policy files)
  `InvalidAlgorithmParameterException` - if the given algorithm parameters are inappropriate for this cipher, or this cipher requires algorithm parameters and `params` is `null`, or the given algorithm parameters imply a cryptographic strength that would exceed the legal limits (as determined from the configured jurisdiction policy files)
  `UnsupportedOperationException` - if `opmode` is `WRAP_MODE` or `UNWRAP_MODE` but the mode is not implemented by the underlying `CipherSpi`
  `InvalidParameterException` - if `opmode` is not one of the recognized values

### init

public final void init(int opmode, Key key, AlgorithmParameters params) throws InvalidKeyException, InvalidAlgorithmParameterException
Initializes this `Cipher` object with a key and a set of algorithm parameters.

The `Cipher` object is initialized for one of the following four operations: encryption, decryption, key wrapping or key unwrapping, depending on the value of `opmode`.

If this cipher requires any algorithm parameters and `params` is `null`, the underlying cipher implementation is supposed to generate the required parameters itself (using provider-specific default or random values) if it is being initialized for encryption or key wrapping, and raise an `InvalidAlgorithmParameterException` if it is being initialized for decryption or key unwrapping. The generated parameters can be retrieved using `getParameters` or `getIV` (if the parameter is an IV).

If this cipher requires algorithm parameters that cannot be derived from the input parameters, and there are no reasonable provider-specific default values, initialization will necessarily fail.

If this cipher (including its feedback or padding scheme) requires any random bytes (e.g., for parameter generation), it will get them using the `SecureRandom` implementation of the highest-priority installed provider as the source of randomness. (If none of the installed providers supply an implementation of SecureRandom, a system-provided source of randomness will be used.)

Note that when a `Cipher` object is initialized, it loses all previously-acquired state. In other words, initializing a `Cipher` object is equivalent to creating a new instance of that `Cipher` object and initializing it.

Parameters:
  `opmode` - the operation mode of this `Cipher` object this is one of the following: `ENCRYPT_MODE`, `DECRYPT_MODE`, `WRAP_MODE` or `UNWRAP_MODE`)
  `key` - the encryption key
  `params` - the algorithm parameters
Throws:
  `InvalidKeyException` - if the given key is inappropriate for initializing this cipher, or its keysize exceeds the maximum allowable keysize (as determined from the configured jurisdiction policy files).
  `InvalidAlgorithmParameterException` - if the given algorithm parameters are inappropriate for this cipher, or this cipher requires algorithm parameters and `params` is `null`, or the given algorithm parameters imply a cryptographic strength that would exceed the legal limits (as determined from the configured jurisdiction policy files)
  `UnsupportedOperationException` - if `opmode` is `WRAP_MODE` or `UNWRAP_MODE` but the mode is not implemented by the underlying `CipherSpi`
  `InvalidParameterException` - if `opmode` is not one of the recognized values

### init

public final void init(int opmode, Key key, AlgorithmParameters params, SecureRandom random) throws InvalidKeyException, InvalidAlgorithmParameterException
Initializes this `Cipher` object with a key, a set of algorithm parameters, and a source of randomness.

The `Cipher` object is initialized for one of the following four operations: encryption, decryption, key wrapping or key unwrapping, depending on the value of `opmode`.

If this cipher requires any algorithm parameters and `params` is `null`, the underlying cipher implementation is supposed to generate the required parameters itself (using provider-specific default or random values) if it is being initialized for encryption or key wrapping, and raise an `InvalidAlgorithmParameterException` if it is being initialized for decryption or key unwrapping. The generated parameters can be retrieved using `getParameters` or `getIV` (if the parameter is an IV).

If this cipher requires algorithm parameters that cannot be derived from the input parameters, and there are no reasonable provider-specific default values, initialization will necessarily fail.

If this cipher (including its feedback or padding scheme) requires any random bytes (e.g., for parameter generation), it will get them from `random`.

Note that when a `Cipher` object is initialized, it loses all previously-acquired state. In other words, initializing a `Cipher` object is equivalent to creating a new instance of that `Cipher` object and initializing it.

Parameters:
  `opmode` - the operation mode of this `Cipher` object (this is one of the following: `ENCRYPT_MODE`, `DECRYPT_MODE`, `WRAP_MODE` or `UNWRAP_MODE`)
  `key` - the encryption key
  `params` - the algorithm parameters
  `random` - the source of randomness
Throws:
  `InvalidKeyException` - if the given key is inappropriate for initializing this cipher, or its keysize exceeds the maximum allowable keysize (as determined from the configured jurisdiction policy files)
  `InvalidAlgorithmParameterException` - if the given algorithm parameters are inappropriate for this cipher, or this cipher requires algorithm parameters and `params` is `null`, or the given algorithm parameters imply a cryptographic strength that would exceed the legal limits (as determined from the configured jurisdiction policy files)
  `UnsupportedOperationException` - if `opmode` is `WRAP_MODE` or `UNWRAP_MODE` but the mode is not implemented by the underlying `CipherSpi`
  `InvalidParameterException` - if `opmode` is not one of the recognized values

### init

public final void init(int opmode, Certificate certificate) throws InvalidKeyException
Initializes this `Cipher` object with the public key from the given certificate.

The `Cipher` object is initialized for one of the following four operations: encryption, decryption, key wrapping or key unwrapping, depending on the value of `opmode`.

If the certificate is of type X.509 and has a key usage extension field marked as critical, and the value of the key usage extension field implies that the public key in the certificate and its corresponding private key are not supposed to be used for the operation represented by the value of `opmode`, an `InvalidKeyException` is thrown.

If this cipher requires any algorithm parameters that cannot be derived from the public key in the given certificate, the underlying cipher implementation is supposed to generate the required parameters itself (using provider-specific default or random values) if it is being initialized for encryption or key wrapping, and raise an `InvalidKeyException` if it is being initialized for decryption or key unwrapping. The generated parameters can be retrieved using `getParameters` or `getIV` (if the parameter is an IV).

If this cipher requires algorithm parameters that cannot be derived from the input parameters, and there are no reasonable provider-specific default values, initialization will necessarily fail.

If this cipher (including its feedback or padding scheme) requires any random bytes (e.g., for parameter generation), it will get them using the `SecureRandom` implementation of the highest-priority installed provider as the source of randomness. (If none of the installed providers supply an implementation of SecureRandom, a system-provided source of randomness will be used.)

Note that when a `Cipher` object is initialized, it loses all previously-acquired state. In other words, initializing a `Cipher` object is equivalent to creating a new instance of that `Cipher` object and initializing it.

Parameters:
  `opmode` - the operation mode of this `Cipher` object (this is one of the following: `ENCRYPT_MODE`, `DECRYPT_MODE`, `WRAP_MODE` or `UNWRAP_MODE`)
  `certificate` - the certificate
Throws:
  `InvalidKeyException` - if the public key in the given certificate is inappropriate for initializing this cipher, or this cipher requires algorithm parameters that cannot be determined from the public key in the given certificate, or the keysize of the public key in the given certificate has a keysize that exceeds the maximum allowable keysize (as determined by the configured jurisdiction policy files)
  `UnsupportedOperationException` - if `opmode` is `WRAP_MODE` or `UNWRAP_MODE` but the mode is not implemented by the underlying `CipherSpi`
  `InvalidParameterException` - if `opmode` is not one of the recognized values

### init

public final void init(int opmode, Certificate certificate, SecureRandom random) throws InvalidKeyException
Initializes this `Cipher` object with the public key from the given certificate and a source of randomness.

The `Cipher` object is initialized for one of the following four operations: encryption, decryption, key wrapping or key unwrapping, depending on the value of `opmode`.

If the certificate is of type X.509 and has a key usage extension field marked as critical, and the value of the key usage extension field implies that the public key in the certificate and its corresponding private key are not supposed to be used for the operation represented by the value of `opmode`, an `InvalidKeyException` is thrown.

If this cipher requires any algorithm parameters that cannot be derived from the public key in the given `certificate`, the underlying cipher implementation is supposed to generate the required parameters itself (using provider-specific default or random values) if it is being initialized for encryption or key wrapping, and raise an `InvalidKeyException` if it is being initialized for decryption or key unwrapping. The generated parameters can be retrieved using `getParameters` or `getIV` (if the parameter is an IV).

If this cipher requires algorithm parameters that cannot be derived from the input parameters, and there are no reasonable provider-specific default values, initialization will necessarily fail.

If this cipher (including its feedback or padding scheme) requires any random bytes (e.g., for parameter generation), it will get them from `random`.

Note that when a `Cipher` object is initialized, it loses all previously-acquired state. In other words, initializing a `Cipher` object is equivalent to creating a new instance of that `Cipher` object and initializing it.

Parameters:
  `opmode` - the operation mode of this `Cipher` object (this is one of the following: `ENCRYPT_MODE`, `DECRYPT_MODE`, `WRAP_MODE` or `UNWRAP_MODE`)
  `certificate` - the certificate
  `random` - the source of randomness
Throws:
  `InvalidKeyException` - if the public key in the given certificate is inappropriate for initializing this cipher, or this cipher requires algorithm parameters that cannot be determined from the public key in the given certificate, or the keysize of the public key in the given certificate has a keysize that exceeds the maximum allowable keysize (as determined by the configured jurisdiction policy files)
  `UnsupportedOperationException` - if `opmode` is `WRAP_MODE` or `UNWRAP_MODE` but the mode is not implemented by the underlying `CipherSpi`
  `InvalidParameterException` - if `opmode` is not one of the recognized values

### update

public final byte[] update(byte[] input)
Continues a multiple-part encryption or decryption operation (depending on how this `Cipher` object was initialized), processing another data part.

The bytes in the `input` buffer are processed, and the result is stored in a new buffer.

If `input` has a length of zero, this method returns `null`.

Parameters:
  `input` - the input buffer
Returns:
  the new buffer with the result, or `null` if this cipher is a block cipher and the input data is too short to result in a new block
Throws:
  `IllegalStateException` - if this `Cipher` object is in a wrong state (e.g., has not been initialized, or is not in `ENCRYPT_MODE` or `DECRYPT_MODE`)

### update

public final byte[] update(byte[] input, int inputOffset, int inputLen)
Continues a multiple-part encryption or decryption operation (depending on how this `Cipher` object was initialized), processing another data part.

The first `inputLen` bytes in the `input` buffer, starting at `inputOffset` inclusive, are processed, and the result is stored in a new buffer.

If `inputLen` is zero, this method returns `null`.

Parameters:
  `input` - the input buffer
  `inputOffset` - the offset in `input` where the input starts
  `inputLen` - the input length
Returns:
  the new buffer with the result, or `null` if this cipher is a block cipher and the input data is too short to result in a new block.
Throws:
  `IllegalStateException` - if this `Cipher` object is in a wrong state (e.g., has not been initialized, or is not in `ENCRYPT_MODE` or `DECRYPT_MODE`)

### update

public final int update(byte[] input, int inputOffset, int inputLen, byte[] output) throws ShortBufferException
Continues a multiple-part encryption or decryption operation (depending on how this `Cipher` object was initialized), processing another data part.

The first `inputLen` bytes in the `input` buffer, starting at `inputOffset` inclusive, are processed, and the result is stored in the `output` buffer.

If the `output` buffer is too small to hold the result, a `ShortBufferException` is thrown. In this case, repeat this call with a larger output buffer. Use `getOutputSize` to determine how big the output buffer should be.

If `inputLen` is zero, this method returns a length of zero.

Note: this method should be copy-safe, which means the `input` and `output` buffers can reference the same byte array and no unprocessed input data is overwritten when the result is copied into the output buffer.

Parameters:
  `input` - the input buffer
  `inputOffset` - the offset in `input` where the input starts
  `inputLen` - the input length
  `output` - the buffer for the result
Returns:
  the number of bytes stored in `output`
Throws:
  `IllegalStateException` - if this `Cipher` object is in a wrong state (e.g., has not been initialized, or is not in `ENCRYPT_MODE` or `DECRYPT_MODE`)
  `ShortBufferException` - if the given output buffer is too small to hold the result

### update

public final int update(byte[] input, int inputOffset, int inputLen, byte[] output, int outputOffset) throws ShortBufferException
Continues a multiple-part encryption or decryption operation (depending on how this `Cipher` object was initialized), processing another data part.

The first `inputLen` bytes in the `input` buffer, starting at `inputOffset` inclusive, are processed, and the result is stored in the `output` buffer, starting at `outputOffset` inclusive.

If the `output` buffer is too small to hold the result, a `ShortBufferException` is thrown. In this case, repeat this call with a larger output buffer. Use `getOutputSize` to determine how big the output buffer should be.

If `inputLen` is zero, this method returns a length of zero.

Note: this method should be copy-safe, which means the `input` and `output` buffers can reference the same byte array and no unprocessed input data is overwritten when the result is copied into the output buffer.

Parameters:
  `input` - the input buffer
  `inputOffset` - the offset in `input` where the input starts
  `inputLen` - the input length
  `output` - the buffer for the result
  `outputOffset` - the offset in `output` where the result is stored
Returns:
  the number of bytes stored in `output`
Throws:
  `IllegalStateException` - if this `Cipher` object is in a wrong state (e.g., has not been initialized, or is not in `ENCRYPT_MODE` or `DECRYPT_MODE`)
  `ShortBufferException` - if the given output buffer is too small to hold the result

### update

public final int update(ByteBuffer input, ByteBuffer output) throws ShortBufferException
Continues a multiple-part encryption or decryption operation (depending on how this `Cipher` object was initialized), processing another data part.

All `input.remaining()` bytes starting at `input.position()` are processed. The result is stored in the output buffer. Upon return, the input buffer's position will be equal to its limit; its limit will not have changed. The output buffer's position will have advanced by n, where n is the value returned by this method; the output buffer's limit will not have changed.

If `output.remaining()` bytes are insufficient to hold the result, a `ShortBufferException` is thrown. In this case, repeat this call with a larger output buffer. Use `getOutputSize` to determine how big the output buffer should be.

Note: this method should be copy-safe, which means the `input` and `output` buffers can reference the same block of memory and no unprocessed input data is overwritten when the result is copied into the output buffer.

Parameters:
  `input` - the input ByteBuffer
  `output` - the output ByteByffer
Returns:
  the number of bytes stored in `output`
Throws:
  `IllegalStateException` - if this `Cipher` object is in a wrong state (e.g., has not been initialized, or is not in `ENCRYPT_MODE` or `DECRYPT_MODE`)
  `IllegalArgumentException` - if input and output are the same object
  `ReadOnlyBufferException` - if the output buffer is read-only
  `ShortBufferException` - if there is insufficient space in the output buffer
Since:
  1.5

### doFinal

public final byte[] doFinal() throws IllegalBlockSizeException, BadPaddingException
Finishes a multiple-part encryption or decryption operation, depending on how this `Cipher` object was initialized.

Input data that may have been buffered during a previous `update` operation is processed, with padding (if requested) being applied. If an AEAD mode such as GCM/CCM is being used, the authentication tag is appended in the case of encryption, or verified in the case of decryption. The result is stored in a new buffer.

Upon finishing, this method resets this `Cipher` object to the state it was in when previously initialized via a call to `init`. That is, the object is reset and available to encrypt or decrypt (depending on the operation mode that was specified in the call to `init`) more data.

Note: if any exception is thrown, this `Cipher` object may need to be reset before it can be used again.

Returns:
  the new buffer with the result
Throws:
  `IllegalStateException` - if this `Cipher` object is in a wrong state (e.g., has not been initialized, or is not in `ENCRYPT_MODE` or `DECRYPT_MODE`)
  `IllegalBlockSizeException` - if this cipher is a block cipher, no padding has been requested (only in encryption mode), and the total input length of the data processed by this cipher is not a multiple of block size; or if this encryption algorithm is unable to process the input data provided.
  `BadPaddingException` - if this `Cipher` object is in decryption mode, and (un)padding has been requested, but the decrypted data is not bounded by the appropriate padding bytes
  `AEADBadTagException` - if this `Cipher` object is decrypting in an AEAD mode (such as GCM/CCM), and the received authentication tag does not match the calculated value

### doFinal

public final int doFinal(byte[] output, int outputOffset) throws IllegalBlockSizeException, ShortBufferException, BadPaddingException
Finishes a multiple-part encryption or decryption operation, depending on how this `Cipher` object was initialized.

Input data that may have been buffered during a previous `update` operation is processed, with padding (if requested) being applied. If an AEAD mode such as GCM/CCM is being used, the authentication tag is appended in the case of encryption, or verified in the case of decryption. The result is stored in the `output` buffer, starting at `outputOffset` inclusive.

If the `output` buffer is too small to hold the result, a `ShortBufferException` is thrown. In this case, repeat this call with a larger output buffer. Use `getOutputSize` to determine how big the output buffer should be.

Upon finishing, this method resets this `Cipher` object to the state it was in when previously initialized via a call to `init`. That is, the object is reset and available to encrypt or decrypt (depending on the operation mode that was specified in the call to `init`) more data.

Note: if any exception is thrown, this `Cipher` object may need to be reset before it can be used again.

Parameters:
  `output` - the buffer for the result
  `outputOffset` - the offset in `output` where the result is stored
Returns:
  the number of bytes stored in `output`
Throws:
  `IllegalStateException` - if this `Cipher` object is in a wrong state (e.g., has not been initialized, or is not in `ENCRYPT_MODE` or `DECRYPT_MODE`)
  `IllegalBlockSizeException` - if this cipher is a block cipher, no padding has been requested (only in encryption mode), and the total input length of the data processed by this cipher is not a multiple of block size; or if this encryption algorithm is unable to process the input data provided.
  `ShortBufferException` - if the given output buffer is too small to hold the result
  `BadPaddingException` - if this `Cipher` object is in decryption mode, and (un)padding has been requested, but the decrypted data is not bounded by the appropriate padding bytes
  `AEADBadTagException` - if this `Cipher` object is decrypting in an AEAD mode (such as GCM/CCM), and the received authentication tag does not match the calculated value

### doFinal

public final byte[] doFinal(byte[] input) throws IllegalBlockSizeException, BadPaddingException
Encrypts or decrypts data in a single-part operation, or finishes a multiple-part operation. The data is encrypted or decrypted, depending on how this `Cipher` object was initialized.

The bytes in the `input` buffer, and any input bytes that may have been buffered during a previous `update` operation, are processed, with padding (if requested) being applied. If an AEAD mode such as GCM/CCM is being used, the authentication tag is appended in the case of encryption, or verified in the case of decryption. The result is stored in a new buffer.

Upon finishing, this method resets this `Cipher` object to the state it was in when previously initialized via a call to `init`. That is, the object is reset and available to encrypt or decrypt (depending on the operation mode that was specified in the call to `init`) more data.

Note: if any exception is thrown, this `Cipher` object may need to be reset before it can be used again.

Parameters:
  `input` - the input buffer
Returns:
  the new buffer with the result
Throws:
  `IllegalStateException` - if this `Cipher` object is in a wrong state (e.g., has not been initialized, or is not in `ENCRYPT_MODE` or `DECRYPT_MODE`)
  `IllegalBlockSizeException` - if this cipher is a block cipher, no padding has been requested (only in encryption mode), and the total input length of the data processed by this cipher is not a multiple of block size; or if this encryption algorithm is unable to process the input data provided.
  `BadPaddingException` - if this `Cipher` object is in decryption mode, and (un)padding has been requested, but the decrypted data is not bounded by the appropriate padding bytes
  `AEADBadTagException` - if this `Cipher` object is decrypting in an AEAD mode (such as GCM/CCM), and the received authentication tag does not match the calculated value

### doFinal

public final byte[] doFinal(byte[] input, int inputOffset, int inputLen) throws IllegalBlockSizeException, BadPaddingException
Encrypts or decrypts data in a single-part operation, or finishes a multiple-part operation. The data is encrypted or decrypted, depending on how this `Cipher` object was initialized.

The first `inputLen` bytes in the `input` buffer, starting at `inputOffset` inclusive, and any input bytes that may have been buffered during a previous `update` operation, are processed, with padding (if requested) being applied. If an AEAD mode such as GCM/CCM is being used, the authentication tag is appended in the case of encryption, or verified in the case of decryption. The result is stored in a new buffer.

Upon finishing, this method resets this `Cipher` object to the state it was in when previously initialized via a call to `init`. That is, the object is reset and available to encrypt or decrypt (depending on the operation mode that was specified in the call to `init`) more data.

Note: if any exception is thrown, this `Cipher` object may need to be reset before it can be used again.

Parameters:
  `input` - the input buffer
  `inputOffset` - the offset in `input` where the input starts
  `inputLen` - the input length
Returns:
  the new buffer with the result
Throws:
  `IllegalStateException` - if this `Cipher` object is in a wrong state (e.g., has not been initialized, or is not in `ENCRYPT_MODE` or `DECRYPT_MODE`)
  `IllegalBlockSizeException` - if this cipher is a block cipher, no padding has been requested (only in encryption mode), and the total input length of the data processed by this cipher is not a multiple of block size; or if this encryption algorithm is unable to process the input data provided.
  `BadPaddingException` - if this `Cipher` object is in decryption mode, and (un)padding has been requested, but the decrypted data is not bounded by the appropriate padding bytes
  `AEADBadTagException` - if this `Cipher` object is decrypting in an AEAD mode (such as GCM/CCM), and the received authentication tag does not match the calculated value

### doFinal

public final int doFinal(byte[] input, int inputOffset, int inputLen, byte[] output) throws ShortBufferException, IllegalBlockSizeException, BadPaddingException
Encrypts or decrypts data in a single-part operation, or finishes a multiple-part operation. The data is encrypted or decrypted, depending on how this `Cipher` object was initialized.

The first `inputLen` bytes in the `input` buffer, starting at `inputOffset` inclusive, and any input bytes that may have been buffered during a previous `update` operation, are processed, with padding (if requested) being applied. If an AEAD mode such as GCM/CCM is being used, the authentication tag is appended in the case of encryption, or verified in the case of decryption. The result is stored in the `output` buffer.

If the `output` buffer is too small to hold the result, a `ShortBufferException` is thrown. In this case, repeat this call with a larger output buffer. Use `getOutputSize` to determine how big the output buffer should be.

Upon finishing, this method resets this `Cipher` object to the state it was in when previously initialized via a call to `init`. That is, the object is reset and available to encrypt or decrypt (depending on the operation mode that was specified in the call to `init`) more data.

Note: if any exception is thrown, this `Cipher` object may need to be reset before it can be used again.

Note: this method should be copy-safe, which means the `input` and `output` buffers can reference the same byte array and no unprocessed input data is overwritten when the result is copied into the output buffer.

Parameters:
  `input` - the input buffer
  `inputOffset` - the offset in `input` where the input starts
  `inputLen` - the input length
  `output` - the buffer for the result
Returns:
  the number of bytes stored in `output`
Throws:
  `IllegalStateException` - if this `Cipher` object is in a wrong state (e.g., has not been initialized, or is not in or `ENCRYPT_MODE` or `DECRYPT_MODE`)
  `IllegalBlockSizeException` - if this cipher is a block cipher, no padding has been requested (only in encryption mode), and the total input length of the data processed by this cipher is not a multiple of block size; or if this encryption algorithm is unable to process the input data provided.
  `ShortBufferException` - if the given output buffer is too small to hold the result
  `BadPaddingException` - if this `Cipher` object is in decryption mode, and (un)padding has been requested, but the decrypted data is not bounded by the appropriate padding bytes
  `AEADBadTagException` - if this `Cipher` object is decrypting in an AEAD mode (such as GCM/CCM), and the received authentication tag does not match the calculated value

### doFinal

public final int doFinal(byte[] input, int inputOffset, int inputLen, byte[] output, int outputOffset) throws ShortBufferException, IllegalBlockSizeException, BadPaddingException
Encrypts or decrypts data in a single-part operation, or finishes a multiple-part operation. The data is encrypted or decrypted, depending on how this `Cipher` object was initialized.

The first `inputLen` bytes in the `input` buffer, starting at `inputOffset` inclusive, and any input bytes that may have been buffered during a previous `update` operation, are processed, with padding (if requested) being applied. If an AEAD mode such as GCM/CCM is being used, the authentication tag is appended in the case of encryption, or verified in the case of decryption. The result is stored in the `output` buffer, starting at `outputOffset` inclusive.

If the `output` buffer is too small to hold the result, a `ShortBufferException` is thrown. In this case, repeat this call with a larger output buffer. Use `getOutputSize` to determine how big the output buffer should be.

Upon finishing, this method resets this `Cipher` object to the state it was in when previously initialized via a call to `init`. That is, the object is reset and available to encrypt or decrypt (depending on the operation mode that was specified in the call to `init`) more data.

Note: if any exception is thrown, this `Cipher` object may need to be reset before it can be used again.

Note: this method should be copy-safe, which means the `input` and `output` buffers can reference the same byte array and no unprocessed input data is overwritten when the result is copied into the output buffer.

Parameters:
  `input` - the input buffer
  `inputOffset` - the offset in `input` where the input starts
  `inputLen` - the input length
  `output` - the buffer for the result
  `outputOffset` - the offset in `output` where the result is stored
Returns:
  the number of bytes stored in `output`
Throws:
  `IllegalStateException` - if this `Cipher` object is in a wrong state (e.g., has not been initialized, or is not in `ENCRYPT_MODE` or `DECRYPT_MODE`)
  `IllegalBlockSizeException` - if this cipher is a block cipher, no padding has been requested (only in encryption mode), and the total input length of the data processed by this cipher is not a multiple of block size; or if this encryption algorithm is unable to process the input data provided.
  `ShortBufferException` - if the given output buffer is too small to hold the result
  `BadPaddingException` - if this `Cipher` object is in decryption mode, and (un)padding has been requested, but the decrypted data is not bounded by the appropriate padding bytes
  `AEADBadTagException` - if this `Cipher` object is decrypting in an AEAD mode (such as GCM/CCM), and the received authentication tag does not match the calculated value

### doFinal

public final int doFinal(ByteBuffer input, ByteBuffer output) throws ShortBufferException, IllegalBlockSizeException, BadPaddingException
Encrypts or decrypts data in a single-part operation, or finishes a multiple-part operation. The data is encrypted or decrypted, depending on how this `Cipher` object was initialized.

All `input.remaining()` bytes starting at `input.position()` are processed. If an AEAD mode such as GCM/CCM is being used, the authentication tag is appended in the case of encryption, or verified in the case of decryption. The result is stored in the output buffer. Upon return, the input buffer's position will be equal to its limit; its limit will not have changed. The output buffer's position will have advanced by n, where n is the value returned by this method; the output buffer's limit will not have changed.

If `output.remaining()` bytes are insufficient to hold the result, a `ShortBufferException` is thrown. In this case, repeat this call with a larger output buffer. Use `getOutputSize` to determine how big the output buffer should be.

Upon finishing, this method resets this `Cipher` object to the state it was in when previously initialized via a call to `init`. That is, the object is reset and available to encrypt or decrypt (depending on the operation mode that was specified in the call to `init`) more data.

Note: if any exception is thrown, this `Cipher` object may need to be reset before it can be used again.

Note: this method should be copy-safe, which means the `input` and `output` buffers can reference the same byte array and no unprocessed input data is overwritten when the result is copied into the output buffer.

Parameters:
  `input` - the input ByteBuffer
  `output` - the output ByteBuffer
Returns:
  the number of bytes stored in `output`
Throws:
  `IllegalStateException` - if this `Cipher` object is in a wrong state (e.g., has not been initialized, or is not in `ENCRYPT_MODE` or `DECRYPT_MODE`)
  `IllegalArgumentException` - if input and output are the same object
  `ReadOnlyBufferException` - if the output buffer is read-only
  `IllegalBlockSizeException` - if this cipher is a block cipher, no padding has been requested (only in encryption mode), and the total input length of the data processed by this cipher is not a multiple of block size; or if this encryption algorithm is unable to process the input data provided.
  `ShortBufferException` - if there is insufficient space in the output buffer
  `BadPaddingException` - if this `Cipher` object is in decryption mode, and (un)padding has been requested, but the decrypted data is not bounded by the appropriate padding bytes
  `AEADBadTagException` - if this `Cipher` object is decrypting in an AEAD mode (such as GCM/CCM), and the received authentication tag does not match the calculated value
Since:
  1.5

### wrap

public final byte[] wrap(Key key) throws IllegalBlockSizeException, InvalidKeyException
Wrap a key.

Parameters:
  `key` - the key to be wrapped
Returns:
  the wrapped key
Throws:
  `IllegalStateException` - if this `Cipher` object is in a wrong state (e.g., has not been initialized, or is not in `WRAP_MODE`)
  `IllegalBlockSizeException` - if this cipher is a block cipher, no padding has been requested, and the length of the encoding of the key to be wrapped is not a multiple of the block size
  `InvalidKeyException` - if it is impossible or unsafe to wrap the key with this cipher (e.g., a hardware protected key is being passed to a software-only cipher)
  `UnsupportedOperationException` - if the corresponding method in the `CipherSpi` is not supported

### unwrap

public final Key unwrap(byte[] wrappedKey, String wrappedKeyAlgorithm, int wrappedKeyType) throws InvalidKeyException, NoSuchAlgorithmException
Unwrap a previously wrapped key.

Parameters:
  `wrappedKey` - the key to be unwrapped
  `wrappedKeyAlgorithm` - the algorithm associated with the wrapped key
  `wrappedKeyType` - the type of the wrapped key. This must be one of `SECRET_KEY`, `PRIVATE_KEY`, or `PUBLIC_KEY`
Returns:
  the unwrapped key
Throws:
  `IllegalStateException` - if this `Cipher` object is in a wrong state (e.g., has not been initialized, or is not in `UNWRAP_MODE`)
  `NoSuchAlgorithmException` - if no installed providers can create keys of type `wrappedKeyType` for the `wrappedKeyAlgorithm`
  `InvalidKeyException` - if `wrappedKey` does not represent a wrapped key of type `wrappedKeyType` for the `wrappedKeyAlgorithm`
  `UnsupportedOperationException` - if the corresponding method in the `CipherSpi` is not supported

### getMaxAllowedKeyLength

public static final int getMaxAllowedKeyLength(String transformation) throws NoSuchAlgorithmException
Returns the maximum key length for the specified transformation according to the installed JCE jurisdiction policy files. If JCE unlimited strength jurisdiction policy files are installed, `Integer.MAX_VALUE` will be returned. For more information on the default key sizes and the JCE jurisdiction policy files, please see the Cryptographic defaults and limitations in the JDK Providers Documentation.

Parameters:
  `transformation` - the cipher transformation
Returns:
  the maximum key length in bits or `Integer.MAX_VALUE`
Throws:
  `NullPointerException` - if `transformation` is `null`
  `NoSuchAlgorithmException` - if `transformation` is not a valid transformation, i.e. in the form of "algorithm" or "algorithm/mode/padding"
Since:
  1.5

### getMaxAllowedParameterSpec

public static final AlgorithmParameterSpec getMaxAllowedParameterSpec(String transformation) throws NoSuchAlgorithmException
Returns an {code AlgorithmParameterSpec} object which contains the maximum `Cipher` parameter value according to the jurisdiction policy file. If JCE unlimited strength jurisdiction policy files are installed or there is no maximum limit on the parameters for the specified transformation in the policy file, `null` will be returned.

Parameters:
  `transformation` - the cipher transformation
Returns:
  an {code AlgorithmParameterSpec} object which holds the maximum value or `null`
Throws:
  `NullPointerException` - if `transformation` is `null`
  `NoSuchAlgorithmException` - if `transformation` is not a valid transformation, i.e. in the form of "algorithm" or "algorithm/mode/padding"
Since:
  1.5

### updateAAD

public final void updateAAD(byte[] src)
Continues a multi-part update of the Additional Authentication Data (AAD).

Calls to this method provide AAD to the `Cipher` object when operating in modes such as AEAD (GCM/CCM). If this `Cipher` object is operating in either GCM or CCM mode, all AAD must be supplied before beginning operations on the ciphertext (via the `update` and `doFinal` methods).

Parameters:
  `src` - the buffer containing the Additional Authentication Data
Throws:
  `IllegalArgumentException` - if the `src` byte array is `null`
  `IllegalStateException` - if this `Cipher` object is in a wrong state (e.g., has not been initialized, or is not in `ENCRYPT_MODE` or `DECRYPT_MODE`), does not accept AAD, or if operating in either GCM or CCM mode and one of the `update` methods has already been called for the active encryption/decryption operation
  `UnsupportedOperationException` - if the corresponding method in the `CipherSpi` has not been overridden by an implementation
Since:
  1.7

### updateAAD

public final void updateAAD(byte[] src, int offset, int len)
Continues a multi-part update of the Additional Authentication Data (AAD), using a subset of the provided buffer.

Calls to this method provide AAD to the `Cipher` object when operating in modes such as AEAD (GCM/CCM). If this `Cipher` object is operating in either GCM or CCM mode, all AAD must be supplied before beginning operations on the ciphertext (via the `update` and `doFinal` methods).

Parameters:
  `src` - the buffer containing the AAD
  `offset` - the offset in `src` where the AAD input starts
  `len` - the number of AAD bytes
Throws:
  `IllegalArgumentException` - if the `src` byte array is `null`, or the `offset` or `length` is less than 0, or the sum of the `offset` and `len` is greater than the length of the `src` byte array
  `IllegalStateException` - if this `Cipher` object is in a wrong state (e.g., has not been initialized, or is not in `ENCRYPT_MODE` or `DECRYPT_MODE`), does not accept AAD, or if operating in either GCM or CCM mode and one of the `update` methods has already been called for the active encryption/decryption operation
  `UnsupportedOperationException` - if the corresponding method in the `CipherSpi` has not been overridden by an implementation
Since:
  1.7

### updateAAD

public final void updateAAD(ByteBuffer src)
Continues a multi-part update of the Additional Authentication Data (AAD).

Calls to this method provide AAD to the `Cipher` object when operating in modes such as AEAD (GCM/CCM). If this `Cipher` object is operating in either GCM or CCM mode, all AAD must be supplied before beginning operations on the ciphertext (via the `update` and `doFinal` methods).

All `src.remaining()` bytes starting at `src.position()` are processed. Upon return, the input buffer's position will be equal to its limit; its limit will not have changed.

Parameters:
  `src` - the buffer containing the AAD
Throws:
  `IllegalArgumentException` - if the `src ByteBuffer` is `null`
  `IllegalStateException` - if this `Cipher` object is in a wrong state (e.g., has not been initialized, or is not in `ENCRYPT_MODE` or `DECRYPT_MODE`), does not accept AAD, or if operating in either GCM or CCM mode and one of the `update` methods has already been called for the active encryption/decryption operation
  `UnsupportedOperationException` - if the corresponding method in the `CipherSpi` has not been overridden by an implementation
Since:
  1.7

### toString

public String toString()
Returns a `String` representation of this `Cipher` object.

Overrides:
  `toString` in class `Object`
Implementation Note:
  This implementation returns a `String` containing the transformation, mode, and provider of this `Cipher` object. The exact format of the `String` is unspecified and is subject to change.
Returns:
  a String describing this `Cipher` object