public class Rc4
   {
       private const int N = 256;
       private int[] _sbox;
       private readonly byte[] _seedKey;
       private byte[] _data;
       private int _i, _j;
       public Rc4(byte[] seedKey, byte[] data)
       {
           _seedKey = seedKey;
           _data = data;
       }
       public Rc4(byte[] seedKey)
       {
           _seedKey = seedKey;
       }

       public byte[] Data
       {
           get
           {
               return _data;
           }
           set
           {
               _data = value;
           }
       }

       public byte[] EnDeCrypt()
       {
           Rc4Initialize();

           byte[] cipher = new byte[_data.Length];

           for (int k = 0;k < _data.Length;k++)
           {
               byte x = GetNextKeyByte();

               byte cipherBy = (byte)(_data[k] ^ x);

               cipher[k] = cipherBy;
           }

           return cipher;
       }

       public byte GetNextKeyByte()
       {
           _i = (_i + 1) % N;
           _j = (_j + _sbox[_i]) % N;

           var tempSwap = _sbox[_i];

           _sbox[_i] = _sbox[_j];
           _sbox[_j] = tempSwap;

           var k = _sbox[(_sbox[_i] + _sbox[_j]) % N];

           return (byte)k;
       }

       public void Rc4Initialize()
       {
           Initialize();
       }

       public void Rc4Initialize(int drop)
       {
           Initialize();

           for (var i = 0; i < drop; i++)
           {
               GetNextKeyByte();
           }
       }

       private void Initialize()
       {
           _i = 0;
           _j = 0;

           _sbox = new int[N];
           var key = new int[N];

           for (var a = 0; a < N; a++)
           {
               key[a] = _seedKey[a % _seedKey.Length];
               _sbox[a] = a;
           }

           var b = 0;
           for (var a = 0; a < N; a++)
           {
               b = (b + _sbox[a] + key[a]) % N;
               var tempSwap = _sbox[a];

               _sbox[a] = _sbox[b];
               _sbox[b] = tempSwap;
           }
       }
   }