Simple Encrypt/Decrypt PHP

enc_decrypt.php

echo encrypt("itgelo");
echo decrypt("B9mFi5BNEhL0kbSdBauFq+L1MEDCmfnoSfUjQ3moAvw=");

function encrypt($string){
    $key = "secret-key";
    $iv = mcrypt_create_iv(mcrypt_get_iv_size(MCRYPT_RIJNDAEL_128, MCRYPT_MODE_CBC), MCRYPT_DEV_URANDOM);
    $encrypted = base64_encode($iv.mcrypt_encrypt(MCRYPT_RIJNDAEL_128, hash('sha256', $key, true), $string, MCRYPT_MODE_CBC, $iv));
    return $encrypted;
}

function decrypt($encrypted){
    $key = "secret-key";
    $data = base64_decode($encrypted);
    $iv = substr($data, 0, mcrypt_get_iv_size(MCRYPT_RIJNDAEL_128, MCRYPT_MODE_CBC));
    $decrypted = rtrim(mcrypt_decrypt(MCRYPT_RIJNDAEL_128, hash('sha256', $key, true), substr($data, mcrypt_get_iv_size(MCRYPT_RIJNDAEL_128, MCRYPT_MODE_CBC)), MCRYPT_MODE_CBC, $iv), "\0");
    return $decrypted;
}