using System;

using System.Text;

public class Program

{

    internal class CeasarHacker

    {

        private const string SYMBOLS = "ABCDEFGHIJKLMNOPQRSTUVWXYZ";

​

        public const string Name = "Ceasar Hacker";

        public readonly string Description = string.Format(@"

                The Caesar Hacker can hack messages encrypted with the Caesar cipher, even if you don’t know the key. 

                There are only 26 possible keys for the Caesar cipher, so a algorithm can easily try all possible decryptions and display the results.");

​

​

        public void Play()

        {

            Console.WriteLine(Name);

            Console.WriteLine(Description);

​

            while (true)

            {

                Console.WriteLine("\nLet's play !");

​

                Console.WriteLine("Enter the encypted chipher message");

                string encypted = Console.ReadLine();

                if (!string.IsNullOrEmpty(encypted))

                {

                    processCeasarHacker(encypted.ToUpper());

                }

​

                Console.WriteLine("Wanna play again?!");

                var answer = Console.ReadLine();

                if (answer == null || !answer.Contains("y", StringComparison.OrdinalIgnoreCase))

                {

                    break;

                }

            }

​

            Console.WriteLine("Thanks for this game!");

        }

​

​

        private void processCeasarHacker(string input)

        {

            for (int i = 1; i <= SYMBOLS.Length; i++)

            {

                var decrypted = new StringBuilder();

                foreach (char sym in input)

                {

                    if (SYMBOLS.Contains(sym))

                    {

                        int num = SYMBOLS.IndexOf(sym) - i;

​

                        if (num < 0)

                            num += SYMBOLS.Length;

​

                        decrypted.Append(SYMBOLS[num]);

                    }

                    else

                    {

                        decrypted.Append(sym);

                    }

                }

​

                Console.WriteLine(string.Format("Key {0}: {1}", i, decrypted));

            }

        }

    }

    public static void Main()

    {

        var cc = new CeasarHacker();

        cc.Play();

    }

}