AES encryption without IV in PHP and JS gives different result

Question

I have the next code in PHP:

$plain = 'some string to encode';
$key = '01234567891234567890123456789012';
$cipherSuite = 'aes-128-cbc';
$iv = null; // I have to use null, I know it's not safe
$result = @openssl_encrypt($plain, $cipherSuite, $key, null, $iv); // Suppress warning of an empty IV
dd($result); // result is 9VK02Mt8IaS+Bng8SbqhCVXUc5TteHKqt3y/EbaJZ1w=

I'm trying to encode the same in online tool - https://www.devglan.com/online-tools/aes-encryption-decryption. Tool says that key must be 16 byte, so I use just half of key - 0123456789123456

It returns exact same result as PHP. Please note that IV is empty.

I need to do the same encryption (and than decription) in JS using Crypto-js

const CryptoJS = require('crypto-js');

var key = CryptoJS.lib.WordArray.create('01234567891234567890123456789012');
var iv = CryptoJS.lib.WordArray.create('');
//var iv = null;
// var iv = CryptoJS.enc.Hex.parse("");
// var iv = CryptoJS.enc.Base64.parse('');
let cfg = {
    mode: CryptoJS.mode.CBC,
    keySize: 128,
    iv: iv
};
const body = 'some string to encode';
const encryptedBody = CryptoJS.AES.encrypt(body, key, cfg).toString();
console.log( encryptedBody );
// result is VYCEPSx9nmb0FJGf1RiU/daL5nIk/qaJZU82jrlGQws=

Similar example at https://jsfiddle.net/pj76d5ov/

Result in JS is different with PHP. Is there a way to use CryptoJS without IV ?

If I use the key as a string, CryptoJS generates IV based on my key, so I have to use WordArray type.

Then I tried to change iv to some values, but it doesn't help. Setting iv to false or null, or not sending iv at all gives an error.

user_9014097 · Answer

In the PHP code AES-128 is specified. Therefore PHP implicitly truncates the 32 bytes key to the first 16 bytes. In the CryptoJS code only this 16 bytes key may be used.
Furthermore, key and IV are converted most easily with the CryptoJS encoders into a WordArray.
A possible CryptoJS implementation is:

var key = CryptoJS.enc.Utf8.parse('0123456789123456');
var iv = CryptoJS.enc.Hex.parse('00000000000000000000000000000000');

let cfg = {
    mode: CryptoJS.mode.CBC,
    keySize: 128,
    iv: iv
};
const body = 'some string to encode';
const encryptedBody = CryptoJS.AES.encrypt(body, key, cfg).toString();
console.log( encryptedBody ); // result is 9VK02Mt8IaS+Bng8SbqhCVXUc5TteHKqt3y/EbaJZ1w=

A static IV is insecure, but you already know that.

AES encryption without IV in PHP and JS gives different result

1 Answers