How to decrypt Java AES on Nodejs

Question

I have the following code on Java that decrypts AES encryption and I need to do the same on Node.js

private static SecretKeySpec secretKey;
private static byte[] key;

public static void setKey(String myKey) {
    MessageDigest sha = null;
    try {
        key = myKey.getBytes("UTF-8");
        sha = MessageDigest.getInstance("SHA-1");
        key = sha.digest(key);
        key = Arrays.copyOf(key, 16);
        secretKey = new SecretKeySpec(key, "AES");


    } catch (NoSuchAlgorithmException e) {
        e.printStackTrace();
    } catch (UnsupportedEncodingException e) {
        e.printStackTrace();
    }
}

 public static String decrypt(String strToDecrypt, String secret) 
{
    try
    {
        setKey(secret);
        Cipher cipher = Cipher.getInstance("AES/ECB/PKCS5PADDING");
        cipher.init(Cipher.DECRYPT_MODE, secretKey);
        return new String(cipher.doFinal(Base64.getDecoder().decode(strToDecrypt)));
    } 
    catch (Exception e) 
    {
        System.out.println("Error while decrypting: " + e.toString());
    }
    return null;
}

I have tried using Crypt under the following code, but it doesn't give me the same results

  var aesDecrypt = (text, password, bit) => {
  var decipher = crypto.createDecipheriv('aes-' + bit + '-ecb', password, Buffer.alloc(0));
  decipher.setAutoPadding(false);
  return Buffer.concat([
    decipher.update(text, 'base64'),
    decipher.final()
   ]).toString();
  };

How could I mimick that Java code from above into Node.js?

Answer 1

As James says, the Java code is hashing (and truncating) the password to form the key. Also it does use standard padding. The following works for ASCII data:

const crypto = require ('crypto');
const mydecrypt = (pw,ctx) => {
    var h = crypto.createHash('sha1'); h.update(pw,'utf8'); var k = h.digest().slice(0,16);
    var d = crypto.createDecipheriv('aes-128-ecb', k, Buffer.alloc(0)); 
    return Buffer.concat([d.update(ctx,'base64'), d.final()]) .toString();
}
console.log(mydecrypt('password','ks7qtmk7kt5riV/Qyy3glQ=='));

->
testdata

It may not work for non-ASCII data. Java new String(byte[]) uses a JVM-dependent encoding which may be UTF8 or may be something different depending on your platform, build, and environment, none of which you described. OTOH nodejs Buffer.toString() always uses UTF8. You may need to change it to toString(somethingelse) to match the Java.

---

If this 'password' is truly a password, ie chosen or even remembered by one or more human(s), using a simple hash of it is very weak and will probably be broken if used for anything not utterly trivial; you should use a Password-Based Key Derivation Function designed for the purpose by someone competent, like older (PKCS5) PBKDF2 or newer bcrypt, scrypt, or argon2. However, that's not a programming question and is offtopic here; it has been discussed many times and at length on https://crypto.stackexchange.com and https://security.stackexchange.com .