using System;

using System.Security.Cryptography;

using System.Text;

​

public class Program

{

    public static void Main()

    {

        string source = "Hello World!";

        using (SHA256 sha256Hash = SHA256.Create())

        {

            string hash = GetHash(sha256Hash, source);

​

            Console.WriteLine("The SHA256 hash of" + source + " is: " + hash + ".");

​

            Console.WriteLine("Verifying the hash...");

​

            if (VerifyHash(sha256Hash, source, hash))

            {

                Console.WriteLine("The hashes are the same.");

            }

            else

            {

                Console.WriteLine("The hashes are not same.");

            }

        }

    }

​

    private static string GetHash(HashAlgorithm hashAlgorithm, string input)

    {

​

        // Convert the input string to a byte array and compute the hash.

        byte[] data = hashAlgorithm.ComputeHash(Encoding.UTF8.GetBytes(input));

​

        // Create a new Stringbuilder to collect the bytes

        // and create a string.

        var sBuilder = new StringBuilder();

​

        // Loop through each byte of the hashed data

        // and format each one as a hexadecimal string.

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

        {

            sBuilder.Append(data[i].ToString("x2"));

        }

​

        // Return the hexadecimal string.

        return sBuilder.ToString();

    }

​

    // Verify a hash against a string.

    private static bool VerifyHash(HashAlgorithm hashAlgorithm, string input, string hash)

    {

        // Hash the input.

        var hashOfInput = GetHash(hashAlgorithm, input);

​

        // Create a StringComparer an compare the hashes.

        StringComparer comparer = StringComparer.OrdinalIgnoreCase;

​

        return comparer.Compare(hashOfInput, hash) == 0;

    }

}

// The example displays the following output:

//    The SHA256 hash of Hello World! is: 7f83b1657ff1fc53b92dc18148a1d65dfc2d4b1fa3d677284addd200126d9069.

//    Verifying the hash...

//    The hashes are the same.