The user-supplied string
* @return booleanReturns TRUE when the two strings are equal, FALSE otherwise.
* @since 5.6.0 */ function hash_equals($known_string, $user_string) { $key = random_bytes(16); return hash_hmac('sha256', $known_string, $key) === hash_hmac('sha256', $user_string, $key); } } if (!function_exists('hash_pbkdf2')) { /** * Generate a PBKDF2 key derivation of a supplied password * * This is a polyfill to account for pre-PHP5.5 versions * Implementation taken from http://stackoverflow.com/a/5093422/1602850 * Modified to implement the $raw_output behaviour * * @link http://php.net/manual/en/function.hash-pbkdf2.php * @param $algo * @param $password * @param $salt * @param $iterations * @param $length [optional] * @param $raw_output [optional] * @return mixed a string containing the derived key as lowercase hexits unless * raw_output is set to TRUE in which case the raw * binary representation of the derived key is returned. * @since 5.5.0 */ function hash_pbkdf2($algo, $password, $salt, $iterations, $length = 0, $raw_output = false) { $size = strlen(hash($algo, '', true)); if ($length === 0) { $length = $size; } $len = ceil($length / $size); $result = ''; for ($i = 1; $i <= $len; $i++) { $tmp = hash_hmac($algo, $salt . pack('N', $i), $password, true); $res = $tmp; for ($j = 1; $j < $iterations; $j++) { $tmp = hash_hmac($algo, $tmp, $password, true); $res ^= $tmp; } $result .= $res; } $result = substr($result, 0, $length); return $raw_output ? $result : bin2hex($result); } } use Phlib\Encrypt\EncryptorInterface; use Phlib\Encrypt\InvalidArgumentException; use Phlib\Encrypt\RuntimeException; class OpenSsl implements EncryptorInterface { /** * @var string */ protected $password; /** * @var string */ protected $cipherMethod = 'aes-256-cbc'; /** * @var int */ protected $pbkdf2Iterations = 50000; /** * @var int */ protected $saltLength = 8; protected $ivLength = null; // dependant on cipher method protected $macLength = 32; // strlen(hash_hmac('sha256', '', '', true)) protected $keyLength = 16; // 128 bits /** * OpenSsl constructor * * @param string $password */ public function __construct($password) { $this->password = $password; $this->ivLength = openssl_cipher_iv_length($this->cipherMethod); } /** * @param string $data * @return string */ public function encrypt($data) { $salt = random_bytes($this->saltLength); $iv = random_bytes($this->ivLength); list($encKey, $authKey) = $this->deriveKeys($salt); $encryptedData = openssl_encrypt($data, $this->cipherMethod, $encKey, OPENSSL_RAW_DATA, $iv); $mac = hash_hmac('sha256', $encryptedData . $iv, $authKey, true); return $salt . $iv . $mac . $encryptedData; } /** * @param string $data * @return string */ public function decrypt($data) { if (strlen($data) < $this->saltLength + $this->ivLength + $this->macLength) { throw new InvalidArgumentException('Data is not valid for decryption'); } $salt = substr($data, 0, $this->saltLength); $iv = substr($data, $this->saltLength, $this->ivLength); $mac = substr($data, $this->saltLength + $this->ivLength, $this->macLength); $encryptedData = substr($data, $this->saltLength + $this->ivLength + $this->macLength); list($encKey, $authKey) = $this->deriveKeys($salt); $calculatedMac = hash_hmac('sha256', $encryptedData . $iv, $authKey, true); if (!hash_equals($calculatedMac, $mac)) { throw new RuntimeException('HMAC failed to match'); } $decryptedData = openssl_decrypt($encryptedData, $this->cipherMethod, $encKey, OPENSSL_RAW_DATA, $iv); if ($decryptedData === false) { throw new RuntimeException('Failed to decrypt data'); } return $decryptedData; } /** * Derive the keys for encryption and authentication using the given salt, and the password * * @param string $salt * @return array */ protected function deriveKeys($salt) { $key = hash_pbkdf2('sha256', $this->password, $salt, $this->pbkdf2Iterations, $this->keyLength * 2, true); return str_split($key, $this->keyLength); } }