Drupal 7 encrypt decrypt string example

custom_encrypt_decrypt.php

<?
/**
 *  Function to encrypt and decrypt a string.
 * @param $string
 * @param string $action
 *
 * @return bool|string
 */
function _custom_encrypt_decrypt($string, $action = 'encrypt') {
  $secret_key = 'k;Yj>+kZ@CHBJQDs*G=2!uRXE+4;)H(M';
  $secret_iv = 'F5a:~+EQAj#:>zazNWN6GP3JEWX75h-@';
  $output = FALSE;
  $encrypt_method = "AES-256-CBC";
  $key = hash('sha256', $secret_key);
  $iv = substr(hash('sha256', $secret_iv), 0, 4);
  if ($action == 'encrypt') {
    $output = base64_encode(openssl_encrypt($string, $encrypt_method, $key, 0, $iv));
  }
  elseif ($action == 'decrypt') {
    $output = openssl_decrypt(base64_decode($string), $encrypt_method, $key, 0, $iv);
  }
  return $output;
}