9 views 
Summery Summery
Authenticated Encryption with Associated Data: Decryption
Syntax Syntax
Description Description
Algorithm: AES-256-GCM
This mode uses a 64-bit random nonce with a 64-bit counter. IETF mode uses a 96-bit random nonce with a 32-bit counter.
Parameters Parameters
- $ciphertext
-
(Optional) Encrypted message (with Poly1305 MAC appended)
Default value: ''
- $assocData
-
(Optional) Authenticated Associated Data (unencrypted)
Default value: ''
- $nonce
-
(Optional) Number to be used only Once; must be 8 bytes
Default value: ''
- $key
-
(Optional) Encryption key
Default value: ''
Return Return
(string|bool) The original plaintext message
Source Source
File: wp-includes/sodium_compat/src/Compat.php
public static function crypto_aead_aes256gcm_decrypt(
$ciphertext = '',
$assocData = '',
$nonce = '',
$key = ''
) {
if (!self::crypto_aead_aes256gcm_is_available()) {
throw new SodiumException('AES-256-GCM is not available');
}
ParagonIE_Sodium_Core_Util::declareScalarType($ciphertext, 'string', 1);
ParagonIE_Sodium_Core_Util::declareScalarType($assocData, 'string', 2);
ParagonIE_Sodium_Core_Util::declareScalarType($nonce, 'string', 3);
ParagonIE_Sodium_Core_Util::declareScalarType($key, 'string', 4);
/* Input validation: */
if (ParagonIE_Sodium_Core_Util::strlen($nonce) !== self::CRYPTO_AEAD_AES256GCM_NPUBBYTES) {
throw new SodiumException('Nonce must be CRYPTO_AEAD_AES256GCM_NPUBBYTES long');
}
if (ParagonIE_Sodium_Core_Util::strlen($key) !== self::CRYPTO_AEAD_AES256GCM_KEYBYTES) {
throw new SodiumException('Key must be CRYPTO_AEAD_AES256GCM_KEYBYTES long');
}
if (ParagonIE_Sodium_Core_Util::strlen($ciphertext) < self::CRYPTO_AEAD_AES256GCM_ABYTES) {
throw new SodiumException('Message must be at least CRYPTO_AEAD_AES256GCM_ABYTES long');
}
if (!is_callable('openssl_decrypt')) {
throw new SodiumException('The OpenSSL extension is not installed, or openssl_decrypt() is not available');
}
/** @var string $ctext */
$ctext = ParagonIE_Sodium_Core_Util::substr($ciphertext, 0, -self::CRYPTO_AEAD_AES256GCM_ABYTES);
/** @var string $authTag */
$authTag = ParagonIE_Sodium_Core_Util::substr($ciphertext, -self::CRYPTO_AEAD_AES256GCM_ABYTES, 16);
return openssl_decrypt(
$ctext,
'aes-256-gcm',
$key,
OPENSSL_RAW_DATA,
$nonce,
$authTag,
$assocData
);
}