Encryption Algorithm for Fund Transfer

public function encryption($data)
  {
    $encryptionMethod = "AES-256-CBC";
    $secret = "xxxxxxxxxxxxxxxxxxxxxxxxxx";  //must be 32 char length, key will be shared via email
    $iv = substr($secret, 0, 16);
    $encryptedMessage = openssl_encrypt($data, $encryptionMethod, $secret,0,$iv);
    return $encryptedMessage;
  }