using System;

using System.Text;

using System.Security.Cryptography;

​

public class Program

{

    private const string requestLine = "POST https://api.notserv.com/updates HTTP/1.1\n";

    private const string host = "api.notserv.com";

    private const string date = "Fri, 18 Sep 2020 08:57:24 GMT";

    private const string contentLength = "593";

    private const string body =

@"data:

    - id: 8fb16f51-4955-4fa7-a926-e36ab9ecddf8

      type: datapoint

      links:

        self: /datapoints/8fb16f51-4955-4fa7-a926-e36ab9ecddf8

      attributes: 

        value: ""25.0""

        timestamp: 2021-02-17T17:17:17Z

    - id: 8fb16f51-4955-4fa7-a926-e36ab9ecddf9

      type: datapoint

      links:

        self: /datapoints/8fb16f51-4955-4fa7-a926-e36ab9ecddf9

      attributes: 

        value: ""on""

        timestamp: 2021-02-17T17:17:17Z";

    private const string secret = "TheBestPasswordEver";

​

    private const string concatString = requestLine + host + date + contentLength + body;

    public static void Main()

    {

        var hash = GetHash(

            requestLine,

            host,

            date,

            contentLength,

            body,

            secret

        );

        Console.WriteLine("Hash: " + hash);

    }

​

    private static string GetHash(string requestLine, // Includes CRLF end

 string host, string date, string contentLength, string body, string secret)

    {

        var stringToSign = requestLine + host + date + contentLength + body;

        using (var hmacsha256 = new HMACSHA256(Encoding.Unicode.GetBytes(secret)))

        {

            var bytes = Encoding.Unicode.GetBytes(stringToSign);

            var hashedBytes = hmacsha256.ComputeHash(bytes);

            return Convert.ToBase64String(hashedBytes);

        }

    }

}