Convert SHA-512 hashing from Java to Bash

Question

I have a big code in Java that hashes a string using SHA-512, and I've been unable to get similar results in Bash. So I decided to simplify it the most I was able to hunt for the problem, and came up with this small piece of code:

import java.math.BigInteger;
import java.security.MessageDigest;

class Test {
  public static void main(String []args) throws Exception {
    String SECRET = "secret";
    String STRING = "string";
    MessageDigest digest = MessageDigest.getInstance("SHA-512");
    digest.update(SECRET.getBytes("UTF-8"));
    byte[] d = digest.digest(STRING.getBytes("UTF-8"));
    System.out.println(new BigInteger(1, d).toString(16));
  }
}

which returns:

26620758babadb008ee7b98e1bb07351f08d49228c15f6f31c4ee75cb9a26f5079b81c01f14f78cf5f9639e49d7319ee3c3fcc1f94e686b8d605c93f2ab9fb4

From my understanding, this would be equivalent to:

#!/bin/bash

SECRET="secret"
STRING="string"

echo -n "$STRING" | openssl sha512 -hmac "$SECRET"

but this returns:

c13223b6f7331a608ec24bf3adfd8f599622b4d5b28cd27f9dcf92430a6263f435d07ff59809785ef04c5cb4aefd02357578efc8862e254a7505e26c76806194

The only thing I have noticed is that if I change the value of toString(16), the result changes too. But from reading its documentation, I could not figure out what it does!

Answer 1

Try

echo -n "secretstring" | sha512sum -

I get

026620758babadb008ee7b98e1bb07351f08d49228c15f6f31c4ee75cb9a26f5079b81c01f14f78cf5f9639e49d7319ee3c3fcc1f94e686b8d605c93f2ab9fb4 -

(there is a leading zero). The issue with your command is the argument -hmac. It works here with

echo -n "secretstring" | openssl sha512

Output of

(stdin)= 026620758babadb008ee7b98e1bb07351f08d49228c15f6f31c4ee75cb9a26f5079b81c01f14f78cf5f9639e49d7319ee3c3fcc1f94e686b8d605c93f2ab9fb4

Finally, changing the value you pass to toString() changes the number's radix (or base).