AES-256-ECB encryption in nodejs does not match php MCrypt module - php

Question

I'm receiving an encrypted message from an external party. They're using php and mcrypt for encryption with the following configuration
algo: rijndael-256
mode: ecb
example encrypted message: "a364cb3bb55c2788b25f04ef6867d770771a7d0fdd44462b40233ea76a8bd00d". Its original message is "thank you"
The following images showing the configuration
From my side, I'm using nodejs to decrypt. I have a working version with node-mcrypt binding. But I want to avoid native modules so I'm looking for a pure javascript solution.
I tried node's crypto but its aes-256-ecb produces different (unreadable) output
The working code with MCrypt binding in nodejs:
const decryptAES256 = (encrypted: string, password: string): string => {
try {
const desEcb = new MCrypt('rijndael-256', 'ecb');
desEcb.open(md5(password));
const ciphertext = desEcb.decrypt(new Buffer(encrypted, 'hex'));
const plain = ciphertext.toString();
const isUTF8 = plain.split('').every(c => c.charCodeAt(0) <= 256);
if (!isUTF8) {
throw new Error('Invalid Input');
}
const unpadding = plain
.split('')
.filter(c => c.charCodeAt(0))
.join('');
return unpadding;
} catch (ex) {
console.error('Invalid token');
}
};

Answer 1

When you state "rijndael-256" that maybe specifying a 256-bit block size which is not AES. AES has one block size: 128-bits.
This seems to be born out by the encrypted output which is 32-binary bytes and for an input of "thank you" the output should be one block so it seems the block size is 32-bytes (256-bits).
Do not use mcrypt, it will just cause interoperability problems.
Make sure you are using AES which can be rijndael with a 128-bit block size.
Do not confuse the key size with the block size.
If the input data is not always a multiple of the block size then padding must be added to the input data], specify padding, PKCS#7 (née PKCS#5) padding which may be the default. mcrypt does not support standard padding. If you must interoperate with mcrypt you will need to specify no padding and perform the padding yourself.

Answer 2

After realizing that rijndael 256 is not equivalent to aes 256 (with 128 version is), I opt to find a rijndael specific lib in pure javascript and this is a working code:
const Rijndael = require('rijndael-js');
describe('cipher', () => {
it('should work', () => {
const text = 'thank you';
// + String.fromCharCode(0).repeat(5)
const key = '94a08da1fecbb6e8b46990538c7b50b2';
const cipher = new Rijndael(key, 'ecb');
const ciphertext = cipher.encrypt(text, 256);
expect(ciphertext.toString('hex')).toBe(
'a364cb3bb55c2788b25f04ef6867d770771a7d0fdd44462b40233ea76a8bd00d'
);
const plaintext = cipher.decrypt(ciphertext, 256);
const unpadded = plaintext.toString().replace(/\u0000*$/g, '');
expect(unpadded).toBe(text);
});
});