using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Runtime.Serialization;
using System.Security.Cryptography;
using System.ServiceModel;
using System.Text;

namespace PubSupMea
{
    [ServiceContract]
    public interface IMeasuringDevice
    {
        [OperationContract]
        void Init(string keyPath);

        [OperationContract]
        void Write(string message, byte[] signature);
    }

    [ServiceContract]
    public interface IClient
    {
        [OperationContract]
        Message GetMeasurement();
    }

    class Service1 : IMeasuringDevice, IClient
    {
        static string javniKljuc;
        static Dictionary<int, string> javniKljucevi = new Dictionary<int, string>();
        static List<Message> poruke = new List<Message>();
        static CspParameters csp = new CspParameters();
        static RSACryptoServiceProvider rsa = new RSACryptoServiceProvider(csp);

        public void Init(string keyPath)
        {
            javniKljuc = keyPath;
        }

        public void Write(string message, byte[] signature)
        {
            byte[] hash = null;

            using (SHA256 sha = SHA256Managed.Create())
            {
                hash = sha.ComputeHash(Encoding.UTF8.GetBytes(message));
            }

            using (StreamReader sr = new StreamReader(javniKljuc))
            {
                rsa.FromXmlString(sr.ReadToEnd());
            }

            RSAPKCS1SignatureDeformatter deformatter = new RSAPKCS1SignatureDeformatter(rsa);
            deformatter.SetHashAlgorithm("SHA256");

            if(deformatter.VerifySignature(hash, signature))
            {
                Message m = new Message(message);
                poruke.Add(m);
            }
        }


        public Message GetMeasurement()
        {
            int highest = 0;
            int ind = 0;
            Message zaSlanje = null;

            for(int i = 0; i < poruke.Count; i++)
            {
                if(poruke[i].priority > highest)
                {
                    highest = poruke[i].priority;
                    zaSlanje = new Message(poruke[i]);
                    ind = i;
                }
            }
            poruke.RemoveAt(ind);
            return zaSlanje;
        }
    }
}

using System;
using System.Collections.Generic;
using System.Linq;
using System.ServiceModel;
using System.Text;
using System.Threading;
using System.Threading.Tasks;

namespace Client
{
    class Program
    {
        static ServiceReference1.ClientClient cl = new ServiceReference1.ClientClient();

        static void Main(string[] args)
        {
            while(true)
            {
                ServiceReference1.Message poruka = cl.GetMeasurement();
                Console.WriteLine($"Poruka: [Priority:{ poruka.priority}, Value: { poruka.value}, TimeStamp: { poruka.TimeStamp}");
                Thread.Sleep(5000);
            }
        }
    }
}


using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Security.Cryptography;
using System.Text;
using System.Threading;
using System.Threading.Tasks;

namespace MeasuringDevice
{
    class Program
    {
        static ServiceReference1.MeasuringDeviceClient mdc = new ServiceReference1.MeasuringDeviceClient();
        static CspParameters csp = null;
        static RSACryptoServiceProvider rsa = null;
        const string KEY_PATH = @"C:\temp\key2.txt";

        static void CreateAsmKeys()
        {
            csp = new CspParameters();
            rsa = new RSACryptoServiceProvider(csp);
        }

        static void ExportPublicKey()
        {
            using (StreamWriter sw = new StreamWriter(KEY_PATH))
            {
                sw.WriteLine(rsa.ToXmlString(false));
            }
        }

        static byte[] SignMessage(string message)
        {
            using (SHA256 sha = SHA256Managed.Create())
            {
                var hashValue = sha.ComputeHash(Encoding.UTF8.GetBytes(message));

                var formatter = new RSAPKCS1SignatureFormatter(rsa);
                formatter.SetHashAlgorithm("SHA256");

                return formatter.CreateSignature(hashValue);
            }
        }

        static void Main(string[] args)
        {
            CreateAsmKeys();
            ExportPublicKey();
            mdc.Init(KEY_PATH);

            Random rnd = new Random();

            while(true)
            {
                int priority = rnd.Next(1, 4);
                int value = rnd.Next(0, 101);
                String timeStamp = DateTime.Now.ToString("dd.MM.yyyy. HH.mm.ss");
                string message = $"{priority}:{value}:{timeStamp}";
                Console.WriteLine($"Salje se poruka: [Priority:{priority}, Value:{value}, TimeStamp:{timeStamp}");
                byte[] signature = SignMessage(message);
                mdc.Write($"{message}", signature);

                Thread.Sleep(5000);
            }

        }
    }
}