using System;

using System.Security.Cryptography;

using System.Text;

​

public class Program

{

    public static void Main()

    {

        Console.WriteLine("Should match:  5d672d79c15b13162d9279b0855cfba6789a8edb4c82c400e06b5924a6f2b5d7");

​

        var payload = "AWS4-HMAC-SHA256\n20150830T123600Z\n20150830/us-east-1/iam/aws4_request\nf536975d06c0309214f805bb90ccff089219ecd68b2577efef23edd43b7e1a59";

        var key = "wJalrXUtnFEMI/K7MDENG+bPxRfiCYEXAMPLEKEY";

        var dateStamp = "20150830";

        var regionName = "us-east-1";

        var service = "iam";

​

        var signingKey = GetSignatureKey(key, dateStamp, regionName, service);

        var hexSigningKey = HexEncode(signingKey);

        var signed = HmacSHA256(payload, signingKey);

        var hexSigned = HexEncode(signed);

​

        Console.WriteLine("Calculated:    " + hexSigned.ToString());

    }

​

    private static string HexEncode(byte[] data, bool lowercase = true)

    {

        var sb = new StringBuilder();

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

        {

            sb.Append(data[i].ToString(lowercase ? "x2" : "X2"));

        }

        return sb.ToString();

    }

​

​

    static byte[] HmacSHA256(String data, byte[] key)

    {

        String algorithm = "HmacSHA256";

        KeyedHashAlgorithm kha = KeyedHashAlgorithm.Create(algorithm);

        kha.Key = key;

​

        return kha.ComputeHash(Encoding.UTF8.GetBytes(data));

    }

​

    static byte[] GetSignatureKey(String key, String dateStamp, String regionName, String serviceName)

    {

        byte[] kSecret = Encoding.UTF8.GetBytes(("AWS4" + key).ToCharArray());

        byte[] kDate = HmacSHA256(dateStamp, kSecret);

        byte[] kRegion = HmacSHA256(regionName, kDate);

        byte[] kService = HmacSHA256(serviceName, kRegion);

        byte[] kSigning = HmacSHA256("aws4_request", kService);

​

        return kSigning;

    }

}

​