unable to decrypt data in Node which is encrypted in Java using AES-GCM-256

Question

I am trying to make an API in node.js which decrypts the input that is created by using AES-GCM-256 algo, I am using the same algo in JAVA to encrypt the code but i am not able to decrypt it using node.js

I Have tried many approaches but i am stuck maybe on the tag part & i am getting error 'Unsupported state or unable to authenticate data'

My Java code :

import java.security.SecureRandom;
import java.util.Arrays;
import java.util.Base64;
import javax.crypto.Cipher;
import javax.crypto.KeyGenerator;
import javax.crypto.SecretKey;
import javax.crypto.spec.GCMParameterSpec;
import javax.crypto.spec.SecretKeySpec;
​
public class AES256GCMAlgo {
​
​
        static String plainText = "This is a plain text which need to be encrypted by Java AES 256 GCM Encryption Algorithm";
        public static final int AES_KEY_SIZE = 256;
        public static final int GCM_IV_LENGTH = 12;
        public static final int GCM_TAG_LENGTH = 16;
​
        public static void main(String[] args) throws Exception
        {
            KeyGenerator keyGenerator = KeyGenerator.getInstance("AES");
            keyGenerator.init(AES_KEY_SIZE);
​
            // Generate Key
            SecretKey key = keyGenerator.generateKey();
            byte[] IV = new byte[GCM_IV_LENGTH];
            SecureRandom random = new SecureRandom();
            random.nextBytes(IV);
​
            byte[] encoded = key.getEncoded();
            String output = Base64.getEncoder().withoutPadding().encodeToString(encoded);
            System.out.println("Keep it secret, keep it safe! " + output);
​
​
            String ivoutput = Base64.getEncoder().withoutPadding().encodeToString(IV);
            System.out.println("Keep ivoutput secret, keep it safe! " + ivoutput);
​
            System.out.println("Original Text : " + plainText);
​
            byte[] cipherText = encrypt(plainText.getBytes(), key, IV);
​
            byte[] tagVal = Arrays.copyOfRange(cipherText, cipherText.length - (128 / Byte.SIZE), cipherText.length);
​
            System.out.println("Encrypted Text : " + Base64.getEncoder().encodeToString(cipherText));
​
            System.out.println("Tag Text : " + Base64.getEncoder().encodeToString(tagVal));
​
​
            String input = output ;
            byte[] deencoded = Base64.getDecoder().decode(output);
            SecretKey aesKey = new SecretKeySpec(deencoded, "AES");
​
            String ivinput = ivoutput;
            byte[] ivdeencoded = Base64.getDecoder().decode(ivinput);
​
            String decryptedText = decrypt(cipherText, aesKey, ivdeencoded);
            System.out.println("DeCrypted Text : " + decryptedText);
        }
​
        public static byte[] encrypt(byte[] plaintext, SecretKey key, byte[] IV) throws Exception
        {
            // Get Cipher Instance
            Cipher cipher = Cipher.getInstance("AES/GCM/NoPadding");
​
            // Create SecretKeySpec
            SecretKeySpec keySpec = new SecretKeySpec(key.getEncoded(), "AES");
​
            // Create GCMParameterSpec
            GCMParameterSpec gcmParameterSpec = new GCMParameterSpec(GCM_TAG_LENGTH * 8, IV);
​
            // Initialize Cipher for ENCRYPT_MODE
            cipher.init(Cipher.ENCRYPT_MODE, keySpec, gcmParameterSpec);
​
            // Perform Encryption
            byte[] cipherText = cipher.doFinal(plaintext);
​
​
​
            return cipherText;
        }
​
        public static String decrypt(byte[] cipherText, SecretKey key, byte[] IV) throws Exception
        {
            // Get Cipher Instance
            Cipher cipher = Cipher.getInstance("AES/GCM/NoPadding");
​
            // Create SecretKeySpec
            SecretKeySpec keySpec = new SecretKeySpec(key.getEncoded(), "AES");
​
            // Create GCMParameterSpec
            GCMParameterSpec gcmParameterSpec = new GCMParameterSpec(GCM_TAG_LENGTH * 8, IV);
​
            // Initialize Cipher for DECRYPT_MODE
            cipher.init(Cipher.DECRYPT_MODE, keySpec, gcmParameterSpec);
​
            // Perform Decryption
            byte[] decryptedText = cipher.doFinal(cipherText);
​
            return new String(decryptedText);
        }
    }

My Node.js code

const crypto = require('crypto');
// input created by running above program in java
const ed = 'OGtANbvTLY6Cme2VNAxsiIhBLLwl29oVX7zC5DGmmq4hU/VqNKaGQuSp1Q8liQ94cW/B96OJoJJ2r67jRlQFI4qHCTWFU2qQ8QaNj6WehdVLsf5mDK2aMYjc/vXd1ha/cElMBzFaIp9g==='
const key = 'HuzPEZgzqKOo8VwlnYhNUaPWTWSVDRQ2bMtY6aJAp8I'
const iv = 'kg5ILA0826hrew5w'
const tag = 'jc/vXd1ha/cElMBzFaIp9g==' // last 16 bytes extracted in java

function decrypt(encrypted, ik, iiv, it) {
  let bData = Buffer.from(encrypted, 'base64');
  // console.log(bData.length,bData.length - 64)
  let tag1 = Buffer.from(tag, 'base64');
  // let tag1 = bData.slice((bData.length - 16),bData.length) // also tried slicing last 16 bytes of buffer
  console.log('00000000',tag1.length)
  let iv1 = Buffer.from(iiv, 'base64');
  let key1 = new Buffer(ik, 'base64');
  console.log('aaaaaaaaa')
  let decipher = crypto.createDecipheriv('aes-256-gcm', key1, iv1)
  console.log('bbbbbbbbbbbbb')
  decipher.setAuthTag(tag1);
  console.log('ccccccc')
  let dec = decipher.update(encrypted, 'binary', 'utf8')
  dec += decipher.final('utf8');
  return dec;
}

console.log('devryptedddddd',decrypt(ed,key,iv,tag))

i should get 'This is a plain text which need to be encrypted by Java AES 256 GCM Encryption Algorithm' in the console of node.js but i am getting 'Unsupported state or unable to authenticate data' error. kindly help.

Answer 1

The 'ed' you use is not the output of that Java code for that plaintext, key, and IV. The value I get is in base64

OGtANbvTLY6Cme2VNAxsiIhBLLwl29oVX7zC5DGmmq4hU/VqNKaGQuSp1Q8liQ94cW/B96OJoJJ2r67jRlQFI4qHCTWFU2qQ8QaNj6WehdVLsf5mDK2aMY3P713dYWv3BJTAcxWiKfY=

(the last 22 chars are different). But that value is not the correct value to use in nodejs; Java crypto returns the GCM tag as the last N bytes of the ciphertext, and you correctly copied it from there to a separate variable, but you didn't remove it from the ciphertext. The correct ciphertext to use in nodejs is in base64:

OGtANbvTLY6Cme2VNAxsiIhBLLwl29oVX7zC5DGmmq4hU/VqNKaGQuSp1Q8liQ94cW/B96OJoJJ2r67jRlQFI4qHCTWFU2qQ8QaNj6WehdVLsf5mDK2aMQ==

(20 chars shorter and last 3 chars different).

Finally, your nodejs does bData = Buffer.from(encrypted, 'base64') but then ignores bData and does decipher.update(encrypted, 'binary', 'utf8') -- using the base64 string as binary, which it isn't. With those two changes:

const crypto = require('crypto');

const ed = 'OGtANbvTLY6Cme2VNAxsiIhBLLwl29oVX7zC5DGmmq4hU/VqNKaGQuSp1Q8liQ94cW/B96OJoJJ2r67jRlQFI4qHCTWFU2qQ8QaNj6WehdVLsf5mDK2aMQ=='
const key = 'HuzPEZgzqKOo8VwlnYhNUaPWTWSVDRQ2bMtY6aJAp8I'
const iv = 'kg5ILA0826hrew5w'
const tag = 'jc/vXd1ha/cElMBzFaIp9g==' // last 16 bytes extracted in java

function decrypt(encrypted, ik, iiv, it) {
  let bData = Buffer.from(encrypted, 'base64');
  let tag1 = Buffer.from(tag, 'base64');
  let iv1 = Buffer.from(iiv, 'base64');
  let key1 = new Buffer(ik, 'base64');
  let decipher = crypto.createDecipheriv('aes-256-gcm', key1, iv1)
  decipher.setAuthTag(tag1);
  let dec = decipher.update(bData, 'utf8')
  dec += decipher.final('utf8');
  return dec;
}
console.log(decrypt(ed,key,iv,tag))

I get the correct output, but also a warning that new Buffer() (used for key1) is deprecated; Buffer.from as you used for the other variables is now preferred.