using System;

using System.Text;

using System.Security.Cryptography;

public class Program

{

    public static void Main()

    {

        Send();

    }

    public static void Send()

    {

        //Sender's copy of shared secret key

        string secretKey = "VinceIsCool";

        //values

        string firstName = "Vince";

        string lastName = "Zalamea";

        //append secret key to values       

        string stringToHash = firstName + lastName + secretKey;

        //generate hash of message

        byte[] hash = MD5.Create().ComputeHash(Encoding.ASCII.GetBytes(stringToHash));

        StringBuilder sb = new StringBuilder();

​

        for (int i = 0; i < hash.Length; i++)   

        {   

            sb.Append(hash[i].ToString("X2"));  

        }

        string digest = sb.ToString();

        bool valid = Receive(firstName,lastName,digest);

        Console.WriteLine("Receiver validated message integrity: " + valid);

    }

    public static bool Receive(string firstName, string lastName, string digest)

    {

        //Receiver's copy of shared secret key

        string secretKey = "VinceIsCool";

        //append secret key to values

        string stringToHash = firstName + lastName + secretKey;

        //generate hash of message

        byte[] hash = MD5.Create().ComputeHash(Encoding.ASCII.GetBytes(stringToHash));

        StringBuilder sb = new StringBuilder();

​

        for (int i = 0; i < hash.Length; i++)   

        {   

            sb.Append(hash[i].ToString("X2"));  

        }

        string expectedDigest = sb.ToString();

        return expectedDigest.Equals(digest);

    }

}