Decrypts data

# openssl_decrypt

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

openssl_decrypt — Decrypts data

### Description

openssl_decrypt(
string `$data`,
string `$cipher_algo`,
#[\SensitiveParameter] string `$passphrase`,
int `$options` = 0,
string `$iv` = "",
?string `$tag` = `null`,
string `$aad` = ""
): string|false

Takes a raw or base64 encoded string and decrypts it using a given method and passphrase.

### Parameters

`data`

  The encrypted message to be decrypted.

`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.

  Caution

  There is no key derivation function used for `passphrase` as its name might suggest. The only operation used is padding with `NUL` characters or truncation if the length is different than expected.

`options`

  `options` can be one of `OPENSSL_RAW_DATA`, `OPENSSL_ZERO_PADDING` or `OPENSSL_DONT_ZERO_PAD_KEY`.

`iv`

  A non-`null` Initialization Vector. If the IV is shorter than expected, it is padded with `NUL` characters and warning is emitted; if the passphrase is longer than expected, it is truncated and warning is emitted.

`tag`

  The authentication tag in AEAD cipher mode. If it is incorrect, the authentication fails and the function returns `false`.

  Caution

  The length of the `tag` is not checked by the function. It is the caller's responsibility to ensure that the length of the tag matches the length of the tag retrieved when openssl_encrypt() has been called. Otherwise the decryption may succeed if the given tag only matches the start of the proper tag.

`aad`

  Additional authenticated data.

### Return Values

The decrypted string on success or `false` on failure.

### Errors/Exceptions

Emits an `E_WARNING` level error if an unknown cipher algorithm is passed 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
--- | ---
8.1.0 | `tag` is now nullable.
7.1.0 | The `tag` and `aad` parameters were added.

### See Also

- openssl_encrypt() - Encrypts data

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