Encrypts data

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- PHP Manual
- OpenSSL Functions
- Encrypts data

# openssl_encrypt

(PHP 5 >= 5.3.0, PHP 7, PHP 8)

openssl_encrypt — Encrypts data

### Description

openssl_encrypt(
string `$data`,
string `$cipher_algo`,
string `$passphrase`,
int `$options` = 0,
string `$iv` = "",
string `&$tag` = `null`,
string `$aad` = "",
int `$tag_length` = 16
): string|false

Encrypts given data with given method and key, returns a raw or base64 encoded string

### Parameters

`data`

  The plaintext message data to be encrypted.

`cipher_algo`

  The cipher method. For a list of available cipher methods, use openssl_get_cipher_methods().

`passphrase`

  The passphrase. If the passphrase is shorter than expected, it is silently padded with `NUL` characters; if the passphrase is longer than expected, it is silently truncated.

`options`

  `options` is a bitwise disjunction of the flags `OPENSSL_RAW_DATA` and `OPENSSL_ZERO_PADDING`.

`iv`

  A non-NULL Initialization Vector.

`tag`

  The authentication tag passed by reference when using AEAD cipher mode (GCM or CCM).

`aad`

  Additional authenticated data.

`tag_length`

  The length of the authentication `tag`. Its value can be between 4 and 16 for GCM mode.

### Return Values

Returns the encrypted string on success or `false` on failure.

### Errors/Exceptions

Emits an `E_WARNING` level error if an unknown cipher algorithm is passed in via the `cipher_algo` parameter.

Emits an `E_WARNING` level error if an empty value is passed in via the `iv` parameter.

### Changelog

Version | Description
--- | ---
7.1.0 | The `tag`, `aad` and `tag_length` parameters were added.

### Examples

Example #1 AES Authenticated Encryption in GCM mode example for PHP 7.1+

    <?php//$key should have been previously generated in a cryptographically safe way, like openssl_random_pseudo_bytes$plaintext = "message to be encrypted";$cipher = "aes-128-gcm";if (in_array($cipher, openssl_get_cipher_methods())){    $ivlen = openssl_cipher_iv_length($cipher);    $iv = openssl_random_pseudo_bytes($ivlen);    $ciphertext = openssl_encrypt($plaintext, $cipher, $key, $options=0, $iv, $tag);    //store $cipher, $iv, and $tag for decryption later    $original_plaintext = openssl_decrypt($ciphertext, $cipher, $key, $options=0, $iv, $tag);    echo $original_plaintext."\n";}?>

Example #2 AES Authenticated Encryption example prior to PHP 7.1

    <?php//$key previously generated safely, ie: openssl_random_pseudo_bytes$plaintext = "message to be encrypted";$ivlen = openssl_cipher_iv_length($cipher="AES-128-CBC");$iv = openssl_random_pseudo_bytes($ivlen);$ciphertext_raw = openssl_encrypt($plaintext, $cipher, $key, $options=OPENSSL_RAW_DATA, $iv);$hmac = hash_hmac('sha256', $ciphertext_raw, $key, $as_binary=true);$ciphertext = base64_encode( $iv.$hmac.$ciphertext_raw );//decrypt later....$c = base64_decode($ciphertext);$ivlen = openssl_cipher_iv_length($cipher="AES-128-CBC");$iv = substr($c, 0, $ivlen);$hmac = substr($c, $ivlen, $sha2len=32);$ciphertext_raw = substr($c, $ivlen+$sha2len);$original_plaintext = openssl_decrypt($ciphertext_raw, $cipher, $key, $options=OPENSSL_RAW_DATA, $iv);$calcmac = hash_hmac('sha256', $ciphertext_raw, $key, $as_binary=true);if (hash_equals($hmac, $calcmac))// timing attack safe comparison{    echo $original_plaintext."\n";}?>

### See Also

- openssl_decrypt() - Decrypts data