How can you generate the same MD5 Hashcode in C# and Java?

Question

I have a function that generates a MD5 hash in C# like this:

MD5 md5 = new MD5CryptoServiceProvider();
byte[] result = md5.ComputeHash(data);
StringBuilder s         


        

Answer 1

That should be fine - although you could make the Java code simpler by just calling

byte[] digest = m.digest(bytes);

instead of calling update then digest.

Are you absolutely sure you've got the same data in both cases? Could you post sample programs showing this failing with the same hard-coded data?

EDIT: Here's the sort of test I was thinking of. These two programs give the same result:

C#:

using System;
using System.Security.Cryptography;
using System.Text;

class Test
{
    static void Main()
    {
        byte[] bytes = { 0x35, 0x24, 0x76, 0x12 };
        MD5 md5 = new MD5CryptoServiceProvider();
        byte[] result = md5.ComputeHash(bytes);
        StringBuilder sb = new StringBuilder();
        for (int i = 0; i < result.Length; i++)
        {
            sb.Append(result[i].ToString("x2"));
        }
        Console.WriteLine(sb);
    }
}

Java:

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

public class Test
{
    public static void main(String[] args) throws Exception
    {
        byte[] bytes = { 0x35, 0x24, 0x76, 0x12 };
        MessageDigest m = MessageDigest.getInstance("MD5");
        byte[] digest = m.digest(bytes);
        String hash = new BigInteger(1, digest).toString(16);
        System.out.println(hash);
    }
}