How to change the Node JS HMAC signature creation to Java

Question

I am very rarely use Java and I have an requirement of converting a function in Node.js which builds the HMAC signature for REST POST call to Java

Node JS function :

function buildSignature(buf, secret) {
    const hmac = crypto.createHmac('sha256', Buffer.from(secret, 'utf8'));
    hmac.update(buf);
    return hmac.digest('hex');
}

What I have currently done is:

Mac sha256_HMAC = Mac.getInstance("HmacSHA256");
     SecretKeySpec secret_key = new SecretKeySpec(secret.getBytes(), "HmacSHA256");
     sha256_HMAC.init(secret_key);

     String hash = Base64.encodeBase64String(sha256_HMAC.doFinal(message.getBytes()));
     System.out.println(hash);

This is not working out to be the same.

Can you use a dummy secret, and provide a response for the Node.JS so those only familiar with Java can assist? — Ryan Leach, Jan 11 '18 at 06:40
It's my suspicion that hmac.digest('hex'); isn't base 64 encoded. I'd try converting the response of sha256_HMAC.doFinal(message.getBytes()) to hex instead. — Ryan Leach, Jan 11 '18 at 06:42
See: https://stackoverflow.com/questions/9655181/how-to-convert-a-byte-array-to-a-hex-string-in-java — Ryan Leach, Jan 11 '18 at 06:44

score 1 · Accepted Answer · answered Jan 11 '18 at 06:46

It's my suspicion that hmac.digest('hex'); isn't base 64 encoded. I'd try converting the response of sha256_HMAC.doFinal(message.getBytes()) to hex instead.

How to convert a byte array to a hex string in Java? 's

The answer I would prefer there (since I use Guava in many projects) is

final String hex = BaseEncoding.base16().lowerCase().encode(bytes);

Adapted to your question would be

final String hash = BaseEncoding.base16().lowerCase().encode(sha256_HMAC.doFinal(message.getBytes()));

score 0 · Answer 2 · answered Jul 05 '21 at 06:38

  Mac sha256_HMAC;
  sha256_HMAC = Mac.getInstance("HmacSHA256");
  SecretKeySpec secret_key = new SecretKeySpec(secret.getBytes("UTF-8"), "HmacSHA256");
  sha256_HMAC.init(secret_key);
  byte[] hash = sha256_HMAC.doFinal(payload.getBytes());
  return new String(Hex.encodeHex(hash));

How to change the Node JS HMAC signature creation to Java

2 Answers2