mcrypt使用PHP加密

Question

I was using the following code from http://www.warpconduit.net/2013/04/14/highly-secure-data-encryption-decryption-made-easy-with-php-mcrypt-rijndael-256-and-cbc/ when I realized that it generated different encrypted strings for the same input strings. However, I require the same output for the same string. How can I achieve this while still retaining some security from the functions?

<?php
function encrypt($encrypt){
    $key = "d0a7e7997b6d5fcd55f4b5c32611b87cd923e88837b63bf2941ef819dc8ca282";
    $encrypt = serialize($encrypt);
    $iv = mcrypt_create_iv(mcrypt_get_iv_size(MCRYPT_RIJNDAEL_256, MCRYPT_MODE_CBC), MCRYPT_RAND);
    $key = pack('H*', $key);
    $mac = hash_hmac('sha256', $encrypt, substr(bin2hex($key), -32));
    $passcrypt = mcrypt_encrypt(MCRYPT_RIJNDAEL_256, $key, $encrypt.$mac, MCRYPT_MODE_CBC, $iv);
    $encoded = base64_encode($passcrypt).'|'.base64_encode($iv);
    return $encoded;
}

function decrypt($decrypt){
    $key = "d0a7e7997b6d5fcd55f4b5c32611b87cd923e88837b63bf2941ef819dc8ca282";
    $decrypt = explode('|', $decrypt);
    $decoded = base64_decode($decrypt[0]);
    $iv = base64_decode($decrypt[1]);
    if(strlen($iv)!==mcrypt_get_iv_size(MCRYPT_RIJNDAEL_256, MCRYPT_MODE_CBC)){ return false; }
    $key = pack('H*', $key);
    $decrypted = trim(mcrypt_decrypt(MCRYPT_RIJNDAEL_256, $key, $decoded, MCRYPT_MODE_CBC, $iv));
    $mac = substr($decrypted, -64);
    $decrypted = substr($decrypted, 0, -64);
    $calcmac = hash_hmac('sha256', $decrypted, substr(bin2hex($key), -32));
    if($calcmac!==$mac){ return false; }
    $decrypted = unserialize($decrypted);
    return $decrypted;
}
?>