Encrypt in Nodejs and Decrypt in PHP

Question

I'm trying to decrypt a string in PHP which was originally encrypted in NodeJS.

PHP:

openssl_decrypt($raw_id, "aes-128-cbc", "s7UbmJpfm56r6CAC6mz7KVZdRc3Fxc4m", 0, null)

This seems to always returnfalse.

Encryption in Nodejs:

function encrypt(text) {
    var cipher = crypto.createCipher('aes-128-cbc', 's7UbmJpfm56r6CAC6mz7KVZdRc3Fxc4m');
    var encrypted = cipher.update(text, 'utf8', 'hex')
    encrypted  += cipher.final('hex')

    return encrypted; 
}

function decrypt(text) {
    var cipher = crypto.createDecipher('aes-128-cbc', 's7UbmJpfm56r6CAC6mz7KVZdRc3Fxc4m');
    var decrypted = cipher.update(text, 'hex', 'utf8')
    decrypted += cipher.final('utf8');

    return decrypted;
}

I basically want to encrypt, for example, encrypt("Pizza") in Nodejs, send it to the PHP page (3879f91a59e9a458db62f905b0a488a1), and decrypt it from there (openssl_decrypt: return Pizza).

I know this code is not safe, since I'm not using an IV but I'm not sure how to add one.

weegee · Accepted Answer · 2019-02-02 20:52:46Z

1

Your method is not secure and can also be victim to man in the middle attacks, you should always use a IV and a HMAC
You can encrypt in php like this

$key = substr('encyptionsec123342',0,32)
function encrypt ($message, $method, $secret, &$hmac) {
    $iv = substr(bin2hex(openssl_random_pseudo_bytes(16)),0,16);
    $encrypted = base64_encode($iv) . openssl_encrypt($message, $method, $secret, 0, $iv);
    $hmac = hash_hmac('md5', $encrypted, $secret);
    return $encrypted;
}

function decrypt ($encrypted, $method, $secret, $hmac) {
    if (hash_hmac('md5', $encrypted, $secret) == $hmac) {
        $iv = base64_decode(substr($encrypted, 0, 24));
        return openssl_decrypt(substr($encrypted, 24), $method, $secret, 0, $iv);
    }
}

function encryptWithTSValidation ($message, $method, $secret, &$hmac) {
    date_default_timezone_set('UTC');
    $message = substr(date('c'),0,19) . "$message";
    return encrypt($message, $method, $secret, $hmac);
}

function decryptWithTSValidation ($encrypted, $method, $secret, $hmac, $intervalThreshold) {
    $decrypted = decrypt($encrypted, $method, $secret, $hmac);
    $now = new DateTime();
    $msgDate = new DateTime(str_replace("T"," ",substr($decrypted,0,19)));
    if (($now->getTimestamp() - $msgDate->getTimestamp()) <= $intervalThreshold) {
        return substr($decrypted,19);
    }
}

This is a secure AES-256-CBC method and with HMAC to stop man in the middle attacks.
Node.js

var secret = "encyptionsec123342";
secret = secret.substr(0, 32);
var method = 'AES-256-CBC';
var encrypt = function(message, method, secret, hmac) {
    var iv = crypto.randomBytes(16).toString('hex').substr(0, 16);
    var encryptor = crypto.createCipheriv(method, secret, iv);
    var encrypted = new Buffer.alloc(iv).toString('base64') + encryptor.update(message, 'utf8', 'base64') + encryptor.final('base64');
    hmac = crypto.createHmac('md5', secret).update(encrypted).digest('hex');
    return encrypted;
};
var decrypt = function(encrypted, method, secret, hmac) {
    if (crypto.createHmac('md5', secret).update(encrypted).digest('hex') == hmac) {
        var iv = new Buffer.from(encrypted.substr(0, 24), 'base64').toString();
        var decryptor = crypto.createDecipheriv(method, secret, iv);
        return decryptor.update(encrypted.substr(24), 'base64', 'utf8') + decryptor.final('utf8');
    }
};
var encryptWithTSValidation = function(message, method, secret, hmac) {
    var messageTS = new Date().toISOString().substr(0, 19) + message;
    return encrypt(messageTS, method, secret, hmac);
}
var decryptWithTSValidation = function(encrypted, method, secret, hmac, intervalThreshold) {
    var decrypted = decrypt(encrypted, method, secret, hmac);
    var now = new Date();
    var year = parseInt(decrypted.substr(0, 4)),
        month = parseInt(decrypted.substr(5, 2)) - 1,
        day = parseInt(decrypted.substr(8, 2)),
        hour = parseInt(decrypted.substr(11, 2)),
        minute = parseInt(decrypted.substr(14, 2)),
        second = parseInt(decrypted.substr(17, 2));
    var msgDate = new Date(Date.UTC(year, month, day, hour, minute, second))
    if (Math.round((now - msgDate) / 1000) <= intervalThreshold) {
        return decrypted.substr(19);
    }
}

To perform encryption and decryption in php,

$encrypted = encryptWithTSValidation($recipent, $method, $key, $hmac);
$decrypted = decryptWithTSValidation($encrypted,$method,$key, $hmac, 60*60*12)//this is 12 hours

to generate a hmac, you can use simple md5 hashing

$hmac = hash_hmac('md5', $recipent, $key);

and in node.js

var decrypted = decryptWithTSValidation(encString, method, secret, hmac, 60 * 60);
var encrypted = decryptWithTSValidation(string, method, secret, hmac);

NOTE: Make sure to make a unique key that is of 32 bit and is same while encryption and decryption in nodejs and php. Also keep it safe and never store it in a database.
Code Reference : Encrypt string in PHP and decrypt in Node.js

edited Feb 2, 2019 at 20:52

answered Feb 2, 2019 at 16:51

weegee

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7 Comments

weegee Over a year ago

@AppelFlap Happy to help

kelalaka Over a year ago

What is the MitM attack here? If you want to suggest a better alternative suggest Authenticated Encryption as AES-GCM that is included in TLS 1.4

weegee Over a year ago

@kelalaka nodejs is used for “real-time” applications, it may be possible the user is using it in web sockets etc.

kelalaka Over a year ago

The MitM attacker

weegee Over a year ago

@kelalaka no i mean the op might be using it in direct communications like webscokets maybe that's why he's integrating node.js and php like i once did

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