How to Securely Encrypt Data in PHP and Decrypt It Using CryptoJS?

Encrypt with PHP, Decrypt with Javascript (cryptojs)

Problem Statement:

You're facing challenges in basic encryption/decryption, specifically involving encryption in PHP and decryption in Javascript using cryptojs.

Clarification:

Your PHP code encompasses encryption with the mcrypt library and base64 encoding. Meanwhile, your Javascript code attempts to decrypt the encrypted text using CryptoJS, but you encounter difficulties.

Resolution:

The provided code incorporates outdated encryption techniques, specifically mcrypt, which is no longer recommended for use. To achieve your encryption/decryption goals, you can leverage AES encryption implemented in PHP's openssl library.

PHP Encryption/Decryption Implementation:

<?php function encrypt($passphrase, $value)
{
    $salt = openssl_random_pseudo_bytes(8);
    $salted = '';
    $dx = '';
    while (strlen($salted) < 48) {
        $dx = md5($dx . $passphrase . $salt, true);
        $salted .= $dx;
    }
    $key = substr($salted, 0, 32);
    $iv = substr($salted, 32, 16);
    $encrypted_data = openssl_encrypt(json_encode($value), 'aes-256-cbc', $key, true, $iv);
    $data = array("ct" => base64_encode($encrypted_data), "iv" => bin2hex($iv), "s" => bin2hex($salt));
    return json_encode($data);
}

function decrypt($passphrase, $jsonStr)
{
    $j = json_decode($jsonStr, true);
    $cipherParams = CryptoJS.lib.CipherParams.create({
        ciphertext: CryptoJS.enc.Base64.parse(j.ct)
    });
    if (j.iv) $cipherParams.iv = CryptoJS.enc.Hex.parse(j.iv)
    if (j.s) $cipherParams.salt = CryptoJS.enc.Hex.parse(j.s)

    $key = substr($result, 0, 32);
    $data = openssl_decrypt($ct, 'aes-256-cbc', $key, true, $iv);
    return json_decode($data, true);
}

Javascript Decryption Implementation:

function decrypt(passphrase, encryptedData) {
    var cipherParams = CryptoJSAesJson.parse(encryptedData);
    var decrypted = CryptoJS.AES.decrypt(cipherParams, passphrase, {format: CryptoJSAesJson}).toString(CryptoJS.enc.Utf8);
    return decrypted;
}

Example Usage:

$encrypted = encrypt('my passphrase', 'value to encrypt');
echo $encrypted; // Encrypted data with salt, iv, and cipher text

var decrypted = decrypt('my passphrase', $encrypted);
console.log(decrypted); // Original 'value to encrypt'

This approach ensures secure and interoperable encryption/decryption between PHP and Javascript, leveraging up-to-date encryption techniques and maintaining compatibility with cryptojs.

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