ГОСТ

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

namespace GOST
{
    class Program
    {
        public static int[][] mat = new int[8][];

        public static string To8(string s)
        {
            while (s.Length < 16)
                s = "0" + s ;
            return s;
        }

        public static string To4(string s)
        {
            while (s.Length < 4)
                s = "0" + s;
            return s;
        }

        public static string To32(string s)
        {
            while (s.Length < 32)
                s = "0" + s;
            return s;
        }



        static void Main(string[] args)
        {
            Console.WriteLine("Введите исходное сообщение");
            string s = Console.ReadLine();
            char[] source = s.ToArray();

            Console.WriteLine("UNICODE");
            foreach (var item in source)
            {
                Console.WriteLine((int)item);
            }
            Console.WriteLine("HEX");
            foreach (var item in source)
            {
                Console.WriteLine(Convert.ToString(item, 2));
            }
            Console.WriteLine("Введите ключ");
            s = Console.ReadLine();
            char[] key = s.ToArray();
            Console.WriteLine("UNICODE");
            foreach (var item in key)
            {
                Console.WriteLine((int)item);
            }
            Console.WriteLine("HEX");
            foreach (var item in key)
            {
                Console.WriteLine(Convert.ToString(item, 2));
            }
            Console.ReadKey();

            string m1 = To8(Convert.ToString(source[2], 2));
            string m2 = To8(Convert.ToString(source[3], 2));
            string m3 = To8(Convert.ToString(key[0], 2));
            string m4 = To8(Convert.ToString(key[1], 2));

            Console.WriteLine(m1 + "  " + m2 + "  " + m3 + "  " + m4);
            Console.ReadKey();
            string m12 = string.Format("{0}{1}", To8(m1), To8(m2));
            string m34 = string.Format("{0}{1}", To8(m3), To8(m4));
            Console.WriteLine("source + source   |   key + key // DigitFormat");
            Console.WriteLine(m12 + "   " + m34);
            long mm12 = Convert.ToInt64(m12, 2);
            long mm34 = Convert.ToInt64(m34, 2);
            Console.WriteLine(mm12 + "     " + mm34);
            string sum = Convert.ToString(Convert.ToInt32(m12, 2) + Convert.ToInt32(m34, 2), 2);
            Console.WriteLine(sum + " HEXFormat");
            Console.ReadKey();
            sum = To32(sum);
            List<int> R0 = new List<int>();
            mat[0] = new int[] { 4, 10, 9, 2, 13, 8, 0, 14, 6, 11, 1, 12, 7, 15, 5, 3 };
            mat[1] = new int[] { 14, 11, 4, 12, 6, 13, 15, 10, 2, 3, 8, 1, 0, 7, 5, 9 };
            mat[2] = new int[] { 5, 8, 1, 13, 10, 3, 4, 2, 14, 15, 12, 7, 6, 0, 9, 11 };
            mat[3] = new int[] { 7, 13, 10, 1, 0, 8, 9, 15, 14, 4, 6, 12, 11, 2, 5, 3 };
            mat[4] = new int[] { 6, 12, 7, 1, 5, 15, 13, 8, 4, 10, 9, 14, 0, 3, 11, 2 };
            mat[5] = new int[] { 4, 11, 10, 0, 7, 2, 1, 13, 3, 6, 8, 5, 9, 12, 15, 14 };
            mat[6] = new int[] { 13, 11, 4, 1, 3, 15, 5, 9, 0, 10, 14, 7, 6, 8, 2, 12 };
            mat[7] = new int[] { 1, 15, 13, 0, 5, 7, 10, 4, 9, 2, 3, 14, 6, 11, 8, 12 };

            for (int i = 0; i < sum.Length; i += 4)
            {
                Console.WriteLine(Convert.ToInt32(sum.Substring(i, 4), 2));
                R0.Add(mat[7 - i / 4][Convert.ToInt32(sum.Substring(i, 4), 2)]);
            }
            string sR0 = "";
            foreach (var item in R0)
            {
                sR0 += To4(Convert.ToString(item, 2));
            }

            Console.WriteLine("Преобразование по таблице: " + sR0);

            sR0 = sR0.Substring(11, sR0.Length-11) + sR0.Substring(0, 11);
            Console.WriteLine("Сдвиг на 11 бит");
            Console.ReadKey();

            int L0 = Convert.ToInt32(To8(Convert.ToString(source[0], 2)) + To8(Convert.ToString(source[1], 2)), 2);
            long R1 = Convert.ToInt64(sR0, 2);
            long answer = L0 ^ R1;
            Console.WriteLine("ОТВЕТ:" + To32(Convert.ToString(answer, 2)));
            Console.ReadKey();
        }
    }
}