CODEWITHSUNDEEP
phpencryptionmcrypt
Sander
Sander

Reputation: 1

Mcrypt not decrypting

I'm working on a small program that has to encrypt a basic sentence and echo the result. Then I want to be able to copy paste the result and be able to decode the text in the same way I encoded it. It doesn't need to be too safe, so therefore I opted to use Mcrypt.

When I try to decrypt, it gives weird (ASCII?) letters and I don't understand where they come from. Tried to solve it with a base64 encode/decode, but that didn't help either. What do I need to change to get it to work properly?

<?php

// Define Mcrypt variables
$enc = MCRYPT_RIJNDAEL_128;
$mode = MCRYPT_MODE_CBC;
$key = 'SanderDitIsNodigVoor16bi';
$iv = mcrypt_create_iv(mcrypt_get_iv_size($enc, $mode), MCRYPT_DEV_URANDOM);

// Check if 'submit' is set
if (isset($_POST['submit'])) {

    // Check if 'text' is set
    if (!empty($_POST['text'])) {

        // Check if 'crypt' is set
        if (isset($_POST['crypt'])) {

            // Retrieve 'text'
            $input = $_POST['text'];

            // Check for encrypt/decrypt
            switch ($_POST['crypt']) {
                case 'encrypt':
                    $result = encrypt();
                    break;
                case 'decrypt':
                    $result = decrypt();
                    break;
            }

            echo $result;
        }

        // If 'crypt' is not set
        else {
            echo 'Please select encrypt or decrypt.';
        }
    }

    // If 'text' is not set
    else {
        echo 'Please fill in some text.';
    }
}

function encrypt() {
    global $enc, $key, $input, $mode, $iv;
    $encrypted = mcrypt_encrypt($enc, $key, $input, $mode, $iv);
    $output = base64_encode($encrypted);
    return $output;
}

function decrypt() {
    global $enc, $key, $input, $mode, $iv;
    $decrypted = base64_decode($input);
    $output = mcrypt_decrypt($enc, $key, $decrypted, $mode, $iv);
    return $output;
}

?>

To be clear, if I include the mcrypt_decrypt in the encryption to make sure it's not something I messed up in the function itself, it does decrypt it properly. But when I try to separate the two, it doesn't. I'm stumped.

Upvotes: 0

Views: 286

Answers (1)

hassan
hassan

Reputation: 8308

you are sending to both encrypt and decrypt the same input , which is :

$input = $_POST['text'];

encrypt will encrypt successfully , but you are always trying to decrypt 'decrypted' phrase !

you must pass the encrypted phrase to decrypt function

and don't forget about the important note that mcrypt_* extension has been deprecated :

This extension rely in libmcrypt which is dead, unmaintained since 2007.

Please don't rely on it, consider switching to well maintained alternatives (openssl, crypt, password hashing functions, phpseclib, password_compat...)

and , try to stop using global variables , it isn't recommended .

Upvotes: 1

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