using System;

using System.IO;

using System.Security.Cryptography;

using System.Text;

using System.Linq;

using System.Numerics;

using System.Collections.Generic;

​

public class Program

{

    private static string ValidChars = "QAZ2WSX3" + "EDC4RFV5" + "TGB6YHN7" + "UJM8K9LP";

     static void Example()

        {

            //

            // Encrypt a small sample of data

            //

         var nextChallenge="BLME1234";

        var  hexString = string.Join("",nextChallenge.Select(c => String.Format("{0:X2}", Convert.ToInt32(c))));

        Console.WriteLine(hexString);

            String Plain =hexString;// "The quick brown fox";

            byte[] plainBytes = Encoding.UTF8.GetBytes(Plain);

            Console.WriteLine("plaintext length is " + plainBytes.Length);

            Console.WriteLine("Plaintext is " + BitConverter.ToString(plainBytes));

​

            byte [] savedKey = new byte[16];

            byte [] savedIV = new byte[16];

            byte[] cipherBytes;

            using (RijndaelManaged Aes128 = new RijndaelManaged())

            {

                //

                // Specify a blocksize of 128, and a key size of 128, which make this

                // instance of RijndaelManaged an instance of AES 128.

                //

                Aes128.BlockSize = 128;

                Aes128.KeySize = 128;

​

                //

                // Specify CFB8 mode

                //

                Aes128.Mode = CipherMode.CFB;

                Aes128.FeedbackSize = 8;

                Aes128.Padding = PaddingMode.None;

                //

                // Generate and save random key and IV.

                //

                Aes128.GenerateKey();

                Aes128.GenerateIV();

​

                Aes128.Key.CopyTo(savedKey, 0);

                Aes128.IV.CopyTo(savedIV, 0);

​

                using (var encryptor = Aes128.CreateEncryptor())

                using (var msEncrypt = new MemoryStream())

                using (var csEncrypt = new CryptoStream(msEncrypt, encryptor, CryptoStreamMode.Write))

                using (var bw = new BinaryWriter(csEncrypt, Encoding.UTF8))

                {

                    bw.Write(plainBytes);

                    bw.Close();

​

                    cipherBytes = msEncrypt.ToArray();

                    foreach(var encoding in Encoding.GetEncodings())

        {

            Console.WriteLine(encoding.Name+ ":" + Encoding.GetEncoding(encoding.Name).GetString(cipherBytes));

        }

                    //Console.WriteLine(Encoding.GetEncoding("1253").GetString(cipherBytes));

                    //Console.WriteLine(Encoding.UTF7.GetString(cipherBytes));

                    //Console.WriteLine(Encoding.ASCII.GetString(cipherBytes));

                    //Console.WriteLine("Encrypt ==> String "+GetStringFromByteArray(cipherBytes));

                    //Console.WriteLine("Encrypt ==> ToBase32String "+GetStringFromByteArray(cipherBytes));

                    //Console.WriteLine(Encoding.UTF8.GetString(cipherBytes));

                    //Console.WriteLine(Convert.ToBase64String(cipherBytes).Length);

                    //Console.WriteLine("Cipher length is " + cipherBytes.Length);

                   // Console.WriteLine("Cipher text is " + BitConverter.ToString(cipherBytes));

                }

            }

​

            //

            // Now decrypt the cipher back to plaintext

            //

​

            using (RijndaelManaged Aes128 = new RijndaelManaged())

            {

                Aes128.BlockSize = 128;

                Aes128.KeySize = 128;

                Aes128.Mode = CipherMode.CFB;

                Aes128.FeedbackSize = 8;

                Aes128.Padding = PaddingMode.None;

​

                Aes128.Key = savedKey;

                Aes128.IV = savedIV;

​

                using (var decryptor = Aes128.CreateDecryptor())

                using (var msEncrypt = new MemoryStream(cipherBytes))

                using (var csEncrypt = new CryptoStream(msEncrypt, decryptor, CryptoStreamMode.Read))

                using (var br = new BinaryReader(csEncrypt, Encoding.UTF8))

                {

                    //csEncrypt.FlushFinalBlock();

                    plainBytes = br.ReadBytes(cipherBytes.Length);

​

                    //Console.WriteLine("Decrypted plain length is " + plainBytes.Length);

                    //Console.WriteLine("Decrypted plain text bytes is " + BitConverter.ToString(plainBytes));

                    //Console.WriteLine("Decrypted plain text is " + Encoding.UTF8.GetString(plainBytes));

                }

            }

        }

    public static string GetStringFromByteArray(byte[] data)

        {

            //string mapping = "ABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789abcdefghijklmnopqrstuvqwxyz!#$%&()*+-;<=>?@^_`{|}~',./:[]\\\"";

        string mapping = "ABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789abcdefghijklmnopqrstuvqwxyz";

​

            BigInteger base10 = new BigInteger(data);

        Console.WriteLine(base10);

            string baseX;

          int baseInt=mapping.Length;

            var result = new Stack<char>();

​

            do

            {

                result.Push(mapping[(int)(base10 % baseInt)]);

                base10 /= baseInt;

​

            } while (base10 != 0);

​

            baseX = new string(result.ToArray());

​

            return baseX;

        }

    public static string ToBase32String(byte[] bytes) {

            StringBuilder sb = new StringBuilder();         // holds the base32 chars

            byte index;

            int hi = 5;

            int currentByte = 0;

​

            while (currentByte < bytes.Length) {

                  // do we need to use the next byte?

                  if (hi > 8) {

                        // get the last piece from the current byte, shift it to the right

                        // and increment the byte counter

                        index = (byte)(bytes[currentByte++] >> (hi - 5));

                        if (currentByte != bytes.Length) {

                              // if we are not at the end, get the first piece from

                              // the next byte, clear it and shift it to the left

                              index = (byte)(((byte)(bytes[currentByte] << (16 - hi)) >> 3) | index);

                        }

​

                        hi -= 3;

                  } else if(hi == 8) { 

                        index = (byte)(bytes[currentByte++] >> 3);

                        hi -= 3; 

                  } else {

​

                        // simply get the stuff from the current byte

                        index = (byte)((byte)(bytes[currentByte] << (8 - hi)) >> 3);

                        hi += 5;

                  }

​

                  sb.Append(ValidChars[index]);

            }

​

            return sb.ToString();

      }

​

       public static void Main(string[] args)

        {

            Example();

        }

}