function aes_decrypt in AES encryption 6

Same name and namespace in other branches

1. 5 aes.module \aes_decrypt()
2. 7 aes.module \aes_decrypt()

aes_decrypt

Description: Decrypts a string of encrypted data.

Arguments: string $string The string to decrypt. (optional) bool $base64encode Whether this encrypted string is base64 encoded or not. (optional) string $custom_key Use this as the key rather than the stored one for this operation. (optional) string $custom_cipher Use this cipher rather than the default one. (only with Mcrypt - ignored with phpseclib) (optional) string $custom_iv Use this initialization vector instead of the default one. (optional) string $custom_implementation Can be "phpseclib" or "mcrypt". Warning: Does not check if the requested implementation actually exists.

Returns: The decrypted string on success, false on error.

2 calls to aes_decrypt()

aes_config_submit in ./aes.module

aes_get_password in ./aes.module

File

./aes.module, line 692

Code

function aes_decrypt($string, $base64encoded = true, $custom_key = null, $custom_cipher = null, $custom_iv = null, $custom_implementation = null) {

  //bail out if the passed string is empty
  if (empty($string)) {
    watchdog("aes", "Tried to decrypt an empty string.", array(), WATCHDOG_WARNING);
    return false;
  }
  if ($base64encoded) {
    $string = base64_decode($string);
  }
  if ($custom_cipher != null) {
    $cipher = $custom_cipher;
  }
  else {
    $cipher = variable_get("aes_cipher", "rijndael-128");
  }
  if (!empty($custom_key)) {
    $key = $custom_key;
  }
  else {
    $key = aes_get_key();
  }
  if (is_null($custom_implementation) == false && ($custom_implementation == "mcrypt" || $custom_implementation == "phpseclib")) {
    $implementation = $custom_implementation;
  }
  else {
    $implementation = variable_get("aes_implementation", "mcrypt");
  }
  if ($implementation == "phpseclib") {

    //using phpseclib implementation

    //phpseclib doesn't support custom ciphers and iv's
    if (is_null($custom_cipher) == false) {
      watchdog("aes", "A custom cipher was defined when decrypting a string in the AES module using the phpseclib implementation. This implementation doesn't support custom ciphers therefore the argument was ignored and the decryption was done with the standard cipher.", array(), WATCHDOG_WARNING);
    }
    if (is_null($custom_iv) == false) {
      watchdog("aes", "A custom IV was defined when decrypting a string in the AES module using the phpseclib implementation. This implementation doesn't support custom IV's therefore the argument was ignored and the decryption was done with the standard IV.", array(), WATCHDOG_WARNING);
    }
    aes_load_phpsec();
    $phpsec = new Crypt_AES();
    $phpsec
      ->setKey($key);
    $decrypted = $phpsec
      ->decrypt($string);
  }
  else {
    if ($implementation == "mcrypt") {

      //using mcrypt implementation
      $td = mcrypt_module_open($cipher, "", MCRYPT_MODE_CBC, "");
      $ks = mcrypt_enc_get_key_size($td);
      if ($custom_iv == null) {
        $iv = base64_decode(variable_get("aes_encryption_iv", ""));
      }
      else {
        $iv = base64_decode($custom_iv);
      }
      if (empty($iv)) {
        watchdog("aes", "No initialization vector found while trying to decrypt. Aborting!", array(), WATCHDOG_ERROR);
      }
      $key = substr(sha1($key), 0, $ks);
      mcrypt_generic_init($td, $key, $iv);
      $decrypted = mdecrypt_generic($td, $string);
      mcrypt_generic_deinit($td);
      mcrypt_module_close($td);
    }
    else {
      $error_msg = t("Request was sent to decrypt a string with the AES module, but the AES module has no active encryption implementation to work with! Did you forget to run update.php after upgrading this module?");
      if (user_access('administer aes')) {
        drupal_set_message($error_msg, "error");
      }
      watchdog("aes", $error_msg, array(), WATCHDOG_ERROR);
      return false;
    }
  }
  return trim($decrypted);
}