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<?php |
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declare(strict_types = 1); |
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namespace Sop\GCM; |
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use Sop\GCM\Cipher\AES\AESCipher; |
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/** |
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* Implements AES-GCM encryption. |
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*/ |
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abstract class AESGCM |
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{ |
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/** |
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* Encrypt plaintext. |
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* |
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* @param string $plaintext Plaintext to encrypt |
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* @param string $aad Additional authenticated data |
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* @param string $key Encryption key |
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* @param string $iv Initialization vector |
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* @param int $tag_length Authentication tag length in bytes |
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* |
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* @return array Tuple of ciphertext and authentication tag |
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*/ |
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public static function encrypt(string $plaintext, string $aad, string $key, |
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string $iv, int $tag_length = 16): array |
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{ |
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$cipher = AESCipher::fromKeyLength(strlen($key)); |
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if ($cipher->hasNativeCipher()) { |
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return $cipher->nativeEncrypt($plaintext, $aad, $key, $iv, $tag_length); |
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} |
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return self::_getGCM($cipher, $tag_length) |
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->encrypt($plaintext, $aad, $key, $iv); |
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} |
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/** |
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* Decrypt ciphertext. |
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* |
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* @param string $ciphertext Ciphertext to decrypt |
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* @param string $auth_tag Authentication tag to verify |
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* @param string $aad Additional authenticated data |
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* @param string $key Encryption key |
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* @param string $iv Initialization vector |
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* |
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* @throws \Sop\GCM\Exception\AuthenticationException If message authentication fails |
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* |
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* @return string Plaintext |
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*/ |
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public static function decrypt(string $ciphertext, string $auth_tag, |
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string $aad, string $key, string $iv): string |
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{ |
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$cipher = AESCipher::fromKeyLength(strlen($key)); |
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if ($cipher->hasNativeCipher()) { |
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return $cipher->nativeDecrypt($ciphertext, $auth_tag, $aad, $key, $iv); |
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} |
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return self::_getGCM($cipher, strlen($auth_tag)) |
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->decrypt($ciphertext, $auth_tag, $aad, $key, $iv); |
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} |
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/** |
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* Get GCM instance. |
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* |
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* @param AESCipher $cipher Cipher instance |
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* @param int $tag_length Authentication tag length |
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* |
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* @return GCM |
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*/ |
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protected static function _getGCM(AESCipher $cipher, int $tag_length): GCM |
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{ |
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return new GCM($cipher, $tag_length); |
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} |
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} |
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sop /
gcm
