MACTripleDES in PHP

Question

I am trying to get a MAC TripleDES equivalent of the C# MACTripleDES class.

I have tried following mcrypt(), but that is just encoding in TripleDES. I need to get an equivalent MACTripleDES string as the one that is generated in C# to authenticate a message.

I have also looked at PHP's hash_hmac() function but it does not give the option of generating a MAC with TripleDES

Answer 1

I'm not sure since Microsoft didn't bother to say what standard their class conforms to, but I suspect that this NIST document is what the Microsoft class is computing, only using triple DES in place of DES.

I guess you will have to write your own method using the primitives in mcrypt.

EDIT 1:

Inspired by the bounty, I have these two examples showing equivalent result in PHP and C#.

First, C#:

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

namespace TDESMacExample
{
    class MainClass
    {
        public static void Main (string[] args)
        {
            var keyString = "012345678901234567890123";
            var keyBytes = Encoding.ASCII.GetBytes(keyString);
            var mac = new MACTripleDES(keyBytes);
            var data = "please authenticate me example number one oh one point seven niner";
            Console.WriteLine(data.Length);
            var macResult = mac.ComputeHash(Encoding.ASCII.GetBytes(data));
            Console.WriteLine(BitConverter.ToString(macResult));
            // B1-29-14-74-EA-E2-74-2D
        }
    }
}

Next, PHP:

    <?php
    $data = 'please authenticate me example number one oh one point seven niner';
    $key = '012345678901234567890123'; // Key must be 24 bytes long
    $iv = '\x00\x00\x00\x00\x00\x00\x00\x00'; // All zero IV is required

    $cipher = mcrypt_cbc(MCRYPT_3DES, $key, $data, MCRYPT_ENCRYPT, $iv);
    $mac_result = substr($cipher, -8); // Last 8 bytes of the cipher are the MAC

    echo "mac result : " . bin2hex($mac_result);
    echo "<br>";
    ?>