AES/CBC/PKCS5PADDING IV - Decryption in NodeJs (Encrypted in Java)

Question

I am trying to decrypt in NodeJs. It is working in Java. But I am not able to achieve same in Node.

node-version: 8.4

Please find my NodeJs code:

var crypto = require('crypto');
function decryption (message, key) {
var messageArray = Buffer.from(message, 'base64');
  // var kekbuf =  Buffer(key, 'utf8');

  var ivBuffer = new Buffer([0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0]);
  var iv = ivBuffer.slice(0, 16);

  var decipher = crypto.createDecipheriv('aes-256-cbc', key, iv);
  decipher.setAutoPadding(false);
  var dec = decipher.update(messageArray, 'base64');

  dec += decipher.final();
  return dec.toString();
}

Please find working Java decryption code

import javax.crypto.Cipher;
import javax.crypto.SecretKey;
import javax.crypto.spec.IvParameterSpec;
import javax.crypto.spec.SecretKeySpec;
import javax.xml.bind.DatatypeConverter;

class Test1 {
  public String decrypt(String message, String key) throws Exception {
    DatatypeConverter dtc = null;
    byte[] messagArray = dtc.parseBase64Binary(message);
    byte[] keyArray = dtc.parseBase64Binary(key);

    byte[] iv = { 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0 };
    IvParameterSpec ivspec = new IvParameterSpec(iv);

    SecretKey secretKey = new SecretKeySpec(keyArray, "AES");
    Cipher cipher = Cipher.getInstance("AES/CBC/PKCS5PADDING");

    cipher.init(Cipher.DECRYPT_MODE, secretKey, ivspec);
    return new String(cipher.doFinal(messagArray));
  }
}

I am getting a different decrypted text. I am not able to achieve the same result in NodeJs as I had in Java. Also, I could not modify my java encryption code. So I have to figure out decryption in Node.

Could you please help me with this.

Answer 1

Here are complete examples in Java and also Node.js, they use the same keys/iv/plaintext and will produce identical results.

Java

import javax.crypto.Cipher;
import javax.crypto.SecretKey;
import javax.crypto.spec.IvParameterSpec;
import javax.crypto.spec.SecretKeySpec;
import javax.xml.bind.DatatypeConverter;
import java.nio.charset.StandardCharsets;

class AES
{
    public AES()
    {
    }

    public String encrypt(String plainText, String keyBase64, String ivBase64) throws Exception
    {
        byte[] plainTextArray = plainText.getBytes(StandardCharsets.UTF_8);
        byte[] keyArray = DatatypeConverter.parseBase64Binary(keyBase64);
        byte[] iv = DatatypeConverter.parseBase64Binary(ivBase64);
        
        SecretKeySpec secretKey = new SecretKeySpec(keyArray, "AES");
        Cipher cipher = Cipher.getInstance("AES/CBC/PKCS5PADDING");   
        cipher.init(Cipher.ENCRYPT_MODE, secretKey, new IvParameterSpec(iv));
        return new String(DatatypeConverter.printBase64Binary(cipher.doFinal(plainTextArray)));
    }
    
    public String decrypt(String messageBase64, String keyBase64, String ivBase64) throws Exception {

        byte[] messageArray = DatatypeConverter.parseBase64Binary(messageBase64);
        byte[] keyArray = DatatypeConverter.parseBase64Binary(keyBase64);
        byte[] iv = DatatypeConverter.parseBase64Binary(ivBase64);

        SecretKey secretKey = new SecretKeySpec(keyArray, "AES");
        Cipher cipher = Cipher.getInstance("AES/CBC/PKCS5PADDING");
        cipher.init(Cipher.DECRYPT_MODE, secretKey, new IvParameterSpec(iv));
        return new String(cipher.doFinal(messageArray));
    }
  
    public static void main(String[] args) {
    
        try
        {   
            String plainText = "Hello world!";
            String encryptionKeyBase64 = "DWIzFkO22qfVMgx2fIsxOXnwz10pRuZfFJBvf4RS3eY=";
            String ivBase64 = "AcynMwikMkW4c7+mHtwtfw==";
            
            AES AES = new AES();
            
            String cipherText = AES.encrypt(plainText, encryptionKeyBase64, ivBase64);
            String decryptedCipherText = AES.decrypt(cipherText, encryptionKeyBase64, ivBase64);
            
            System.out.println("Plaintext: " + plainText);
            System.out.println("Ciphertext: " + cipherText);
            System.out.println("Decrypted text: " + decryptedCipherText);
        }
        catch (Exception e)
        {
            System.out.println(e.toString());
        }
    }
}

Node.js

var crypto = require('crypto');

function getAlgorithm(keyBase64) {
    
    var key = Buffer.from(keyBase64, 'base64');
    switch (key.length) {
        case 16:
            return 'aes-128-cbc';
        case 32:
            return 'aes-256-cbc';
            
    }
    
    throw new Error('Invalid key length: ' + key.length);
}


function encrypt(plainText, keyBase64, ivBase64) {

    const key = Buffer.from(keyBase64, 'base64');
    const iv = Buffer.from(ivBase64, 'base64');

    const cipher = crypto.createCipheriv(getAlgorithm(keyBase64), key, iv);
    let encrypted = cipher.update(plainText, 'utf8', 'base64')
    encrypted += cipher.final('base64');
    return encrypted;
};

function decrypt (messagebase64, keyBase64, ivBase64) {

    const key = Buffer.from(keyBase64, 'base64');
    const iv = Buffer.from(ivBase64, 'base64');

    const decipher = crypto.createDecipheriv(getAlgorithm(keyBase64), key, iv);
    let decrypted = decipher.update(messagebase64, 'base64');
    decrypted += decipher.final();
    return decrypted;
}


var keyBase64 = "DWIzFkO22qfVMgx2fIsxOXnwz10pRuZfFJBvf4RS3eY=";
var ivBase64 = 'AcynMwikMkW4c7+mHtwtfw==';
var plainText = 'Why, then, ’tis none to you, for there is nothing either good or bad, but thinking makes it so';

var cipherText = encrypt(plainText, keyBase64, ivBase64);
var decryptedCipherText = decrypt(cipherText, keyBase64, ivBase64);

console.log('Algorithm: ' + getAlgorithm(keyBase64));
console.log('Plaintext: ' + plainText);
console.log('Ciphertext: ' + cipherText);
console.log('Decoded Ciphertext: ' + decryptedCipherText);