context: using System;
  
  using Nequeo.Cryptography.Key.Crypto.Parameters;
  
  namespace Nequeo.Cryptography.Key.Crypto.Engines
  {
      /**
      * Serpent is a 128-bit 32-round block cipher with variable key lengths,
      * including 128, 192 and 256 bit keys conjectured to be at least as
      * secure as three-key triple-DES.
      * <p>
      * Serpent was designed by Ross Anderson, Eli Biham and Lars Knudsen as a
      * candidate algorithm for the NIST AES Quest.>
  	* </p>
      * <p>
      * For full details see the <a href="http://www.cl.cam.ac.uk/~rja14/serpent.html">The Serpent home page</a>
  	* </p>
      */
      public class SerpentEngine
  		: IBlockCipher
      {
          private const int    BLOCK_SIZE = 16;
  
          static readonly int ROUNDS = 32;
          static readonly int PHI    = unchecked((int)0x9E3779B9);       // (Sqrt(5) - 1) * 2**31
  
          private bool        encrypting;
          private int[]          wKey;
  
          private int           X0, X1, X2, X3;    // registers
  
          /**
          * initialise a Serpent cipher.
          *
          * @param forEncryption whether or not we are for encryption.
          * @param parameters the parameters required to set up the cipher.
          * @exception ArgumentException if the parameters argument is
          * inappropriate.
          */
          public void Init(
              bool				forEncryption,
              ICipherParameters	parameters)
          {
              if (!(parameters is KeyParameter))
  				throw new ArgumentException("invalid parameter passed to Serpent init - " + parameters.GetType().ToString());
  
  			this.encrypting = forEncryption;
              this.wKey = MakeWorkingKey(((KeyParameter)parameters).GetKey());
          }
  
  		public string AlgorithmName
  		{
  			get { return "Serpent"; }
  		}
  
  		public bool IsPartialBlockOkay
  		{
  			get { return false; }
  		}
  
  		public int GetBlockSize()
          {
              return BLOCK_SIZE;
          }
  
          /**
          * Process one block of input from the array in and write it to
          * the out array.
          *
          * @param in the array containing the input data.
          * @param inOff offset into the in array the data starts at.
          * @param out the array the output data will be copied into.
          * @param outOff the offset into the out array the output will start at.
          * @exception DataLengthException if there isn't enough data in in, or
          * space in out.
          * @exception InvalidOperationException if the cipher isn't initialised.
          * @return the number of bytes processed and produced.
          */
          public  int ProcessBlock(
              byte[]  input,
              int     inOff,
              byte[]  output,
              int     outOff)
          {
              if (wKey == null)
                  throw new InvalidOperationException("Serpent not initialised");
              if ((inOff + BLOCK_SIZE) > input.Length)
                  throw new DataLengthException("input buffer too short");
              if ((outOff + BLOCK_SIZE) > output.Length)
                  throw new DataLengthException("output buffer too short");
  
  			if (encrypting)
              {
                  EncryptBlock(input, inOff, output, outOff);
              }
              else
              {
                  DecryptBlock(input, inOff, output, outOff);
              }
  
              return BLOCK_SIZE;
          }
  
          public void Reset()
          {
          }
  
          /**
          * Expand a user-supplied key material into a session key.
          *
          * @param key  The user-key bytes (multiples of 4) to use.
          * @exception ArgumentException
          */
          private int[] MakeWorkingKey(
              byte[] key)
          {
              //
              // pad key to 256 bits
              //
              int[]   kPad = new int[16];
              int     off = 0;
              int     length = 0;
  
              for (off = key.Length - 4; off > 0; off -= 4)
              {
                  kPad[length++] = BytesToWord(key, off);
              }
  
              if (off == 0)
              {
                  kPad[length++] = BytesToWord(key, 0);
                  if (length < 8)
                  {
                      kPad[length] = 1;
                  }
              }
              else
              {
                  throw new ArgumentException("key must be a multiple of 4 bytes");
              }
  
              //
              // expand the padded key up to 33 x 128 bits of key material
              //
              int amount = (ROUNDS + 1) * 4;
              int[] w = new int[amount];
  
              //
              // compute w0 to w7 from w-8 to w-1
              //
              for (int i = 8; i < 16; i++)
              {
                  kPad[i] = RotateLeft(kPad[i - 8] ^ kPad[i - 5] ^ kPad[i - 3] ^ kPad[i - 1] ^ PHI ^ (i - 8), 11);
              }
  
              Array.Copy(kPad, 8, w, 0, 8);
  
              //
              // compute w8 to w136
              //
              for (int i = 8; i < amount; i++)
              {
                  w[i] = RotateLeft(w[i - 8] ^ w[i - 5] ^ w[i - 3] ^ w[i - 1] ^ PHI ^ i, 11);
              }
  
              //
              // create the working keys by processing w with the Sbox and IP
              //
              Sb3(w[0], w[1], w[2], w[3]);
              w[0] = X0; w[1] = X1; w[2] = X2; w[3] = X3;
              Sb2(w[4], w[5], w[6], w[7]);
              w[4] = X0; w[5] = X1; w[6] = X2; w[7] = X3;
              Sb1(w[8], w[9], w[10], w[11]);
              w[8] = X0; w[9] = X1; w[10] = X2; w[11] = X3;
              Sb0(w[12], w[13], w[14], w[15]);
              w[12] = X0; w[13] = X1; w[14] = X2; w[15] = X3;
              Sb7(w[16], w[17], w[18], w[19]);
              w[16] = X0; w[17] = X1; w[18] = X2; w[19] = X3;
              Sb6(w[20], w[21], w[22], w[23]);
              w[20] = X0; w[21] = X1; w[22] = X2; w[23] = X3;
              Sb5(w[24], w[25], w[26], w[27]);
              w[24] = X0; w[25] = X1; w[26] = X2; w[27] = X3;
              Sb4(w[28], w[29], w[30], w[31]);
              w[28] = X0; w[29] = X1; w[30] = X2; w[31] = X3;
              Sb3(w[32], w[33], w[34], w[35]);
              w[32] = X0; w[33] = X1; w[34] = X2; w[35] = X3;
              Sb2(w[36], w[37], w[38], w[39]);
              w[36] = X0; w[37] = X1; w[38] = X2; w[39] = X3;
              Sb1(w[40], w[41], w[42], w[43]);
              w[40] = X0; w[41] = X1; w[42] = X2; w[43] = X3;
              Sb0(w[44], w[45], w[46], w[47]);
              w[44] = X0; w[45] = X1; w[46] = X2; w[47] = X3;
              Sb7(w[48], w[49], w[50], w[51]);
              w[48] = X0; w[49] = X1; w[50] = X2; w[51] = X3;
              Sb6(w[52], w[53], w[54], w[55]);
              w[52] = X0; w[53] = X1; w[54] = X2; w[55] = X3;
              Sb5(w[56], w[57], w[58], w[59]);
              w[56] = X0; w[57] = X1; w[58] = X2; w[59] = X3;
              Sb4(w[60], w[61], w[62], w[63]);
              w[60] = X0; w[61] = X1; w[62] = X2; w[63] = X3;
              Sb3(w[64], w[65], w[66], w[67]);
              w[64] = X0; w[65] = X1; w[66] = X2; w[67] = X3;
              Sb2(w[68], w[69], w[70], w[71]);
              w[68] = X0; w[69] = X1; w[70] = X2; w[71] = X3;
              Sb1(w[72], w[73], w[74], w[75]);
              w[72] = X0; w[73] = X1; w[74] = X2; w[75] = X3;
              Sb0(w[76], w[77], w[78], w[79]);
              w[76] = X0; w[77] = X1; w[78] = X2; w[79] = X3;
              Sb7(w[80], w[81], w[82], w[83]);
              w[80] = X0; w[81] = X1; w[82] = X2; w[83] = X3;
              Sb6(w[84], w[85], w[86], w[87]);
              w[84] = X0; w[85] = X1; w[86] = X2; w[87] = X3;
              Sb5(w[88], w[89], w[90], w[91]);
              w[88] = X0; w[89] = X1; w[90] = X2; w[91] = X3;
              Sb4(w[92], w[93], w[94], w[95]);
              w[92] = X0; w[93] = X1; w[94] = X2; w[95] = X3;
              Sb3(w[96], w[97], w[98], w[99]);
              w[96] = X0; w[97] = X1; w[98] = X2; w[99] = X3;
              Sb2(w[100], w[101], w[102], w[103]);
              w[100] = X0; w[101] = X1; w[102] = X2; w[103] = X3;
              Sb1(w[104], w[105], w[106], w[107]);
              w[104] = X0; w[105] = X1; w[106] = X2; w[107] = X3;
              Sb0(w[108], w[109], w[110], w[111]);
              w[108] = X0; w[109] = X1; w[110] = X2; w[111] = X3;
              Sb7(w[112], w[113], w[114], w[115]);
              w[112] = X0; w[113] = X1; w[114] = X2; w[115] = X3;
              Sb6(w[116], w[117], w[118], w[119]);
              w[116] = X0; w[117] = X1; w[118] = X2; w[119] = X3;
              Sb5(w[120], w[121], w[122], w[123]);
              w[120] = X0; w[121] = X1; w[122] = X2; w[123] = X3;
              Sb4(w[124], w[125], w[126], w[127]);
              w[124] = X0; w[125] = X1; w[126] = X2; w[127] = X3;
              Sb3(w[128], w[129], w[130], w[131]);
              w[128] = X0; w[129] = X1; w[130] = X2; w[131] = X3;
  
              return w;
          }
  
          private int RotateLeft(
              int     x,
              int     bits)
          {
              return ((x << bits) | (int) ((uint)x >> (32 - bits)));
          }
  
          private int RotateRight(
              int     x,
              int     bits)
          {
              return ( (int)((uint)x >> bits) | (x << (32 - bits)));
          }
  
          private int BytesToWord(
              byte[]  src,
              int     srcOff)
          {
              return (((src[srcOff] & 0xff) << 24) | ((src[srcOff + 1] & 0xff) <<  16) |
              ((src[srcOff + 2] & 0xff) << 8) | ((src[srcOff + 3] & 0xff)));
          }
  
          private void WordToBytes(
              int     word,
              byte[]  dst,
              int     dstOff)
          {
              dst[dstOff + 3] = (byte)(word);
              dst[dstOff + 2] = (byte)((uint)word >> 8);
              dst[dstOff + 1] = (byte)((uint)word >> 16);
              dst[dstOff]     = (byte)((uint)word >> 24);
          }
  
          /**
          * Encrypt one block of plaintext.
          *
          * @param in the array containing the input data.
          * @param inOff offset into the in array the data starts at.
          * @param out the array the output data will be copied into.
          * @param outOff the offset into the out array the output will start at.
          */
          private void EncryptBlock(
              byte[]  input,
              int     inOff,
              byte[]  outBytes,
              int     outOff)
          {
              X3 = BytesToWord(input, inOff);
              X2 = BytesToWord(input, inOff + 4);
              X1 = BytesToWord(input, inOff + 8);
              X0 = BytesToWord(input, inOff + 12);
  
              Sb0(wKey[0] ^ X0, wKey[1] ^ X1, wKey[2] ^ X2, wKey[3] ^ X3); LT();
              Sb1(wKey[4] ^ X0, wKey[5] ^ X1, wKey[6] ^ X2, wKey[7] ^ X3); LT();
              Sb2(wKey[8] ^ X0, wKey[9] ^ X1, wKey[10] ^ X2, wKey[11] ^ X3); LT();
              Sb3(wKey[12] ^ X0, wKey[13] ^ X1, wKey[14] ^ X2, wKey[15] ^ X3); LT();
              Sb4(wKey[16] ^ X0, wKey[17] ^ X1, wKey[18] ^ X2, wKey[19] ^ X3); LT();
              Sb5(wKey[20] ^ X0, wKey[21] ^ X1, wKey[22] ^ X2, wKey[23] ^ X3); LT();
              Sb6(wKey[24] ^ X0, wKey[25] ^ X1, wKey[26] ^ X2, wKey[27] ^ X3); LT();
              Sb7(wKey[28] ^ X0, wKey[29] ^ X1, wKey[30] ^ X2, wKey[31] ^ X3); LT();
              Sb0(wKey[32] ^ X0, wKey[33] ^ X1, wKey[34] ^ X2, wKey[35] ^ X3); LT();
              Sb1(wKey[36] ^ X0, wKey[37] ^ X1, wKey[38] ^ X2, wKey[39] ^ X3); LT();
              Sb2(wKey[40] ^ X0, wKey[41] ^ X1, wKey[42] ^ X2, wKey[43] ^ X3); LT();
              Sb3(wKey[44] ^ X0, wKey[45] ^ X1, wKey[46] ^ X2, wKey[47] ^ X3); LT();
              Sb4(wKey[48] ^ X0, wKey[49] ^ X1, wKey[50] ^ X2, wKey[51] ^ X3); LT();
              Sb5(wKey[52] ^ X0, wKey[53] ^ X1, wKey[54] ^ X2, wKey[55] ^ X3); LT();
              Sb6(wKey[56] ^ X0, wKey[57] ^ X1, wKey[58] ^ X2, wKey[59] ^ X3); LT();
              Sb7(wKey[60] ^ X0, wKey[61] ^ X1, wKey[62] ^ X2, wKey[63] ^ X3); LT();
              Sb0(wKey[64] ^ X0, wKey[65] ^ X1, wKey[66] ^ X2, wKey[67] ^ X3); LT();
              Sb1(wKey[68] ^ X0, wKey[69] ^ X1, wKey[70] ^ X2, wKey[71] ^ X3); LT();
              Sb2(wKey[72] ^ X0, wKey[73] ^ X1, wKey[74] ^ X2, wKey[75] ^ X3); LT();
              Sb3(wKey[76] ^ X0, wKey[77] ^ X1, wKey[78] ^ X2, wKey[79] ^ X3); LT();
              Sb4(wKey[80] ^ X0, wKey[81] ^ X1, wKey[82] ^ X2, wKey[83] ^ X3); LT();
              Sb5(wKey[84] ^ X0, wKey[85] ^ X1, wKey[86] ^ X2, wKey[87] ^ X3); LT();
              Sb6(wKey[88] ^ X0, wKey[89] ^ X1, wKey[90] ^ X2, wKey[91] ^ X3); LT();
              Sb7(wKey[92] ^ X0, wKey[93] ^ X1, wKey[94] ^ X2, wKey[95] ^ X3); LT();
              Sb0(wKey[96] ^ X0, wKey[97] ^ X1, wKey[98] ^ X2, wKey[99] ^ X3); LT();
              Sb1(wKey[100] ^ X0, wKey[101] ^ X1, wKey[102] ^ X2, wKey[103] ^ X3); LT();
              Sb2(wKey[104] ^ X0, wKey[105] ^ X1, wKey[106] ^ X2, wKey[107] ^ X3); LT();
              Sb3(wKey[108] ^ X0, wKey[109] ^ X1, wKey[110] ^ X2, wKey[111] ^ X3); LT();
              Sb4(wKey[112] ^ X0, wKey[113] ^ X1, wKey[114] ^ X2, wKey[115] ^ X3); LT();
              Sb5(wKey[116] ^ X0, wKey[117] ^ X1, wKey[118] ^ X2, wKey[119] ^ X3); LT();
              Sb6(wKey[120] ^ X0, wKey[121] ^ X1, wKey[122] ^ X2, wKey[123] ^ X3); LT();
              Sb7(wKey[124] ^ X0, wKey[125] ^ X1, wKey[126] ^ X2, wKey[127] ^ X3);
  
              WordToBytes(wKey[131] ^ X3, outBytes, outOff);
              WordToBytes(wKey[130] ^ X2, outBytes, outOff + 4);
              WordToBytes(wKey[129] ^ X1, outBytes, outOff + 8);
              WordToBytes(wKey[128] ^ X0, outBytes, outOff + 12);
          }
  
          /**
          * Decrypt one block of ciphertext.
          *
          * @param in the array containing the input data.
          * @param inOff offset into the in array the data starts at.
          * @param out the array the output data will be copied into.
          * @param outOff the offset into the out array the output will start at.
          */
          private void DecryptBlock(
              byte[]  input,
              int     inOff,
              byte[]  outBytes,
              int     outOff)
          {
              X3 = wKey[131] ^ BytesToWord(input, inOff);
              X2 = wKey[130] ^ BytesToWord(input, inOff + 4);
              X1 = wKey[129] ^ BytesToWord(input, inOff + 8);
              X0 = wKey[128] ^ BytesToWord(input, inOff + 12);
  
              Ib7(X0, X1, X2, X3);
              X0 ^= wKey[124]; X1 ^= wKey[125]; X2 ^= wKey[126]; X3 ^= wKey[127];
              InverseLT(); Ib6(X0, X1, X2, X3);
              X0 ^= wKey[120]; X1 ^= wKey[121]; X2 ^= wKey[122]; X3 ^= wKey[123];
              InverseLT(); Ib5(X0, X1, X2, X3);
              X0 ^= wKey[116]; X1 ^= wKey[117]; X2 ^= wKey[118]; X3 ^= wKey[119];
              InverseLT(); Ib4(X0, X1, X2, X3);
              X0 ^= wKey[112]; X1 ^= wKey[113]; X2 ^= wKey[114]; X3 ^= wKey[115];
              InverseLT(); Ib3(X0, X1, X2, X3);
              X0 ^= wKey[108]; X1 ^= wKey[109]; X2 ^= wKey[110]; X3 ^= wKey[111];
              InverseLT(); Ib2(X0, X1, X2, X3);
              X0 ^= wKey[104]; X1 ^= wKey[105]; X2 ^= wKey[106]; X3 ^= wKey[107];
              InverseLT(); Ib1(X0, X1, X2, X3);
              X0 ^= wKey[100]; X1 ^= wKey[101]; X2 ^= wKey[102]; X3 ^= wKey[103];
              InverseLT(); Ib0(X0, X1, X2, X3);
              X0 ^= wKey[96]; X1 ^= wKey[97]; X2 ^= wKey[98]; X3 ^= wKey[99];
              InverseLT(); Ib7(X0, X1, X2, X3);
              X0 ^= wKey[92]; X1 ^= wKey[93]; X2 ^= wKey[94]; X3 ^= wKey[95];
              InverseLT(); Ib6(X0, X1, X2, X3);
              X0 ^= wKey[88]; X1 ^= wKey[89]; X2 ^= wKey[90]; X3 ^= wKey[91];
              InverseLT(); Ib5(X0, X1, X2, X3);
              X0 ^= wKey[84]; X1 ^= wKey[85]; X2 ^= wKey[86]; X3 ^= wKey[87];
              InverseLT(); Ib4(X0, X1, X2, X3);
              X0 ^= wKey[80]; X1 ^= wKey[81]; X2 ^= wKey[82]; X3 ^= wKey[83];
              InverseLT(); Ib3(X0, X1, X2, X3);
              X0 ^= wKey[76]; X1 ^= wKey[77]; X2 ^= wKey[78]; X3 ^= wKey[79];
              InverseLT(); Ib2(X0, X1, X2, X3);
              X0 ^= wKey[72]; X1 ^= wKey[73]; X2 ^= wKey[74]; X3 ^= wKey[75];
              InverseLT(); Ib1(X0, X1, X2, X3);
              X0 ^= wKey[68]; X1 ^= wKey[69]; X2 ^= wKey[70]; X3 ^= wKey[71];
              InverseLT(); Ib0(X0, X1, X2, X3);
              X0 ^= wKey[64]; X1 ^= wKey[65]; X2 ^= wKey[66]; X3 ^= wKey[67];
              InverseLT(); Ib7(X0, X1, X2, X3);
              X0 ^= wKey[60]; X1 ^= wKey[61]; X2 ^= wKey[62]; X3 ^= wKey[63];
              InverseLT(); Ib6(X0, X1, X2, X3);
              X0 ^= wKey[56]; X1 ^= wKey[57]; X2 ^= wKey[58]; X3 ^= wKey[59];
              InverseLT(); Ib5(X0, X1, X2, X3);
              X0 ^= wKey[52]; X1 ^= wKey[53]; X2 ^= wKey[54]; X3 ^= wKey[55];
              InverseLT(); Ib4(X0, X1, X2, X3);
              X0 ^= wKey[48]; X1 ^= wKey[49]; X2 ^= wKey[50]; X3 ^= wKey[51];
              InverseLT(); Ib3(X0, X1, X2, X3);
              X0 ^= wKey[44]; X1 ^= wKey[45]; X2 ^= wKey[46]; X3 ^= wKey[47];
              InverseLT(); Ib2(X0, X1, X2, X3);
              X0 ^= wKey[40]; X1 ^= wKey[41]; X2 ^= wKey[42]; X3 ^= wKey[43];
              InverseLT(); Ib1(X0, X1, X2, X3);
              X0 ^= wKey[36]; X1 ^= wKey[37]; X2 ^= wKey[38]; X3 ^= wKey[39];
              InverseLT(); Ib0(X0, X1, X2, X3);
              X0 ^= wKey[32]; X1 ^= wKey[33]; X2 ^= wKey[34]; X3 ^= wKey[35];
              InverseLT(); Ib7(X0, X1, X2, X3);
              X0 ^= wKey[28]; X1 ^= wKey[29]; X2 ^= wKey[30]; X3 ^= wKey[31];
              InverseLT(); Ib6(X0, X1, X2, X3);
              X0 ^= wKey[24]; X1 ^= wKey[25]; X2 ^= wKey[26]; X3 ^= wKey[27];
              InverseLT(); Ib5(X0, X1, X2, X3);
              X0 ^= wKey[20]; X1 ^= wKey[21]; X2 ^= wKey[22]; X3 ^= wKey[23];
              InverseLT(); Ib4(X0, X1, X2, X3);
              X0 ^= wKey[16]; X1 ^= wKey[17]; X2 ^= wKey[18]; X3 ^= wKey[19];
              InverseLT(); Ib3(X0, X1, X2, X3);
              X0 ^= wKey[12]; X1 ^= wKey[13]; X2 ^= wKey[14]; X3 ^= wKey[15];
              InverseLT(); Ib2(X0, X1, X2, X3);
              X0 ^= wKey[8]; X1 ^= wKey[9]; X2 ^= wKey[10]; X3 ^= wKey[11];
              InverseLT(); Ib1(X0, X1, X2, X3);
              X0 ^= wKey[4]; X1 ^= wKey[5]; X2 ^= wKey[6]; X3 ^= wKey[7];
              InverseLT(); Ib0(X0, X1, X2, X3);
  
              WordToBytes(X3 ^ wKey[3], outBytes, outOff);
              WordToBytes(X2 ^ wKey[2], outBytes, outOff + 4);
              WordToBytes(X1 ^ wKey[1], outBytes, outOff + 8);
              WordToBytes(X0 ^ wKey[0], outBytes, outOff + 12);
          }
  
          /*
          * The sboxes below are based on the work of Brian Gladman and
          * Sam Simpson, whose original notice appears below.
          * <p>
          * For further details see:
          *      http://fp.gladman.plus.com/cryptography_technology/serpent/
  		* </p>
          */
  
          /* Partially optimised Serpent S Box bool functions derived  */
          /* using a recursive descent analyser but without a full search */
          /* of all subtrees. This set of S boxes is the result of work    */
          /* by Sam Simpson and Brian Gladman using the spare time on a    */
          /* cluster of high capacity servers to search for S boxes with    */
          /* this customised search engine. There are now an average of    */
          /* 15.375 terms    per S box.                                        */
          /*                                                              */
          /* Copyright:   Dr B. R Gladman (gladman@seven77.demon.co.uk)   */
          /*                and Sam Simpson (s.simpson@mia.co.uk)            */
          /*              17th December 1998                                */
          /*                                                              */
          /* We hereby give permission for information in this file to be */
          /* used freely subject only to acknowledgement of its origin.    */
  
          /**
          * S0 - { 3, 8,15, 1,10, 6, 5,11,14,13, 4, 2, 7, 0, 9,12 } - 15 terms.
          */
          private void Sb0(int a, int b, int c, int d)
          {
              int    t1 = a ^ d;
              int    t3 = c ^ t1;
              int    t4 = b ^ t3;
              X3 = (a & d) ^ t4;
              int    t7 = a ^ (b & t1);
              X2 = t4 ^ (c | t7);
              int    t12 = X3 & (t3 ^ t7);
              X1 = (~t3) ^ t12;
              X0 = t12 ^ (~t7);
          }
  
          /**
          * InvSO - {13, 3,11, 0,10, 6, 5,12, 1,14, 4, 7,15, 9, 8, 2 } - 15 terms.
          */
          private void Ib0(int a, int b, int c, int d)
          {
              int    t1 = ~a;
              int    t2 = a ^ b;
              int    t4 = d ^ (t1 | t2);
              int    t5 = c ^ t4;
              X2 = t2 ^ t5;
              int    t8 = t1 ^ (d & t2);
              X1 = t4 ^ (X2 & t8);
              X3 = (a & t4) ^ (t5 | X1);
              X0 = X3 ^ (t5 ^ t8);
          }
  
          /**
          * S1 - {15,12, 2, 7, 9, 0, 5,10, 1,11,14, 8, 6,13, 3, 4 } - 14 terms.
          */
          private void Sb1(int a, int b, int c, int d)
          {
              int    t2 = b ^ (~a);
              int    t5 = c ^ (a | t2);
              X2 = d ^ t5;
              int    t7 = b ^ (d | t2);
              int    t8 = t2 ^ X2;
              X3 = t8 ^ (t5 & t7);
              int    t11 = t5 ^ t7;
              X1 = X3 ^ t11;
              X0 = t5 ^ (t8 & t11);
          }
  
          /**
          * InvS1 - { 5, 8, 2,14,15, 6,12, 3,11, 4, 7, 9, 1,13,10, 0 } - 14 steps.
          */
          private void Ib1(int a, int b, int c, int d)
          {
              int    t1 = b ^ d;
              int    t3 = a ^ (b & t1);
              int    t4 = t1 ^ t3;
              X3 = c ^ t4;
              int    t7 = b ^ (t1 & t3);
              int    t8 = X3 | t7;
              X1 = t3 ^ t8;
              int    t10 = ~X1;
              int    t11 = X3 ^ t7;
              X0 = t10 ^ t11;
              X2 = t4 ^ (t10 | t11);
          }
  
          /**
          * S2 - { 8, 6, 7, 9, 3,12,10,15,13, 1,14, 4, 0,11, 5, 2 } - 16 terms.
          */
          private void Sb2(int a, int b, int c, int d)
          {
              int    t1 = ~a;
              int    t2 = b ^ d;
              int    t3 = c & t1;
              X0 = t2 ^ t3;
              int    t5 = c ^ t1;
              int    t6 = c ^ X0;
              int    t7 = b & t6;
              X3 = t5 ^ t7;
              X2 = a ^ ((d | t7) & (X0 | t5));
              X1 = (t2 ^ X3) ^ (X2 ^ (d | t1));
          }
  
          /**
          * InvS2 - {12, 9,15, 4,11,14, 1, 2, 0, 3, 6,13, 5, 8,10, 7 } - 16 steps.
          */
          private void Ib2(int a, int b, int c, int d)
          {
              int    t1 = b ^ d;
              int    t2 = ~t1;
              int    t3 = a ^ c;
              int    t4 = c ^ t1;
              int    t5 = b & t4;
              X0 = t3 ^ t5;
              int    t7 = a | t2;
              int    t8 = d ^ t7;
              int    t9 = t3 | t8;
              X3 = t1 ^ t9;
              int    t11 = ~t4;
              int    t12 = X0 | X3;
              X1 = t11 ^ t12;
              X2 = (d & t11) ^ (t3 ^ t12);
          }
  
          /**
          * S3 - { 0,15,11, 8,12, 9, 6, 3,13, 1, 2, 4,10, 7, 5,14 } - 16 terms.
          */
          private void Sb3(int a, int b, int c, int d)
          {
              int    t1 = a ^ b;
              int    t2 = a & c;
              int    t3 = a | d;
              int    t4 = c ^ d;
              int    t5 = t1 & t3;
              int    t6 = t2 | t5;
              X2 = t4 ^ t6;
              int    t8 = b ^ t3;
              int    t9 = t6 ^ t8;
              int    t10 = t4 & t9;
              X0 = t1 ^ t10;
              int    t12 = X2 & X0;
              X1 = t9 ^ t12;
              X3 = (b | d) ^ (t4 ^ t12);
          }
  
          /**
          * InvS3 - { 0, 9,10, 7,11,14, 6,13, 3, 5,12, 2, 4, 8,15, 1 } - 15 terms
          */
          private void Ib3(int a, int b, int c, int d)
          {
              int    t1 = a | b;
              int    t2 = b ^ c;
              int    t3 = b & t2;
              int    t4 = a ^ t3;
              int    t5 = c ^ t4;
              int    t6 = d | t4;
              X0 = t2 ^ t6;
              int    t8 = t2 | t6;
              int    t9 = d ^ t8;
              X2 = t5 ^ t9;
              int    t11 = t1 ^ t9;
              int    t12 = X0 & t11;
              X3 = t4 ^ t12;
              X1 = X3 ^ (X0 ^ t11);
          }
  
          /**
          * S4 - { 1,15, 8, 3,12, 0,11, 6, 2, 5, 4,10, 9,14, 7,13 } - 15 terms.
          */
          private void Sb4(int a, int b, int c, int d)
          {
              int    t1 = a ^ d;
              int    t2 = d & t1;
              int    t3 = c ^ t2;
              int    t4 = b | t3;
              X3 = t1 ^ t4;
              int    t6 = ~b;
              int    t7 = t1 | t6;
              X0 = t3 ^ t7;
              int    t9 = a & X0;
              int    t10 = t1 ^ t6;
              int    t11 = t4 & t10;
              X2 = t9 ^ t11;
              X1 = (a ^ t3) ^ (t10 & X2);
          }
  
          /**
          * InvS4 - { 5, 0, 8, 3,10, 9, 7,14, 2,12,11, 6, 4,15,13, 1 } - 15 terms.
          */
          private void Ib4(int a, int b, int c, int d)
          {
              int    t1 = c | d;
              int    t2 = a & t1;
              int    t3 = b ^ t2;
              int    t4 = a & t3;
              int    t5 = c ^ t4;
              X1 = d ^ t5;
              int    t7 = ~a;
              int    t8 = t5 & X1;
              X3 = t3 ^ t8;
              int    t10 = X1 | t7;
              int    t11 = d ^ t10;
              X0 = X3 ^ t11;
              X2 = (t3 & t11) ^ (X1 ^ t7);
          }
  
          /**
          * S5 - {15, 5, 2,11, 4,10, 9,12, 0, 3,14, 8,13, 6, 7, 1 } - 16 terms.
          */
          private void Sb5(int a, int b, int c, int d)
          {
              int    t1 = ~a;
              int    t2 = a ^ b;
              int    t3 = a ^ d;
              int    t4 = c ^ t1;
              int    t5 = t2 | t3;
              X0 = t4 ^ t5;
              int    t7 = d & X0;
              int    t8 = t2 ^ X0;
              X1 = t7 ^ t8;
              int    t10 = t1 | X0;
              int    t11 = t2 | t7;
              int    t12 = t3 ^ t10;
              X2 = t11 ^ t12;
              X3 = (b ^ t7) ^ (X1 & t12);
          }
  
          /**
          * InvS5 - { 8,15, 2, 9, 4, 1,13,14,11, 6, 5, 3, 7,12,10, 0 } - 16 terms.
          */
          private void Ib5(int a, int b, int c, int d)
          {
              int    t1 = ~c;
              int    t2 = b & t1;
              int    t3 = d ^ t2;
              int    t4 = a & t3;
              int    t5 = b ^ t1;
              X3 = t4 ^ t5;
              int    t7 = b | X3;
              int    t8 = a & t7;
              X1 = t3 ^ t8;
              int    t10 = a | d;
              int    t11 = t1 ^ t7;
              X0 = t10 ^ t11;
              X2 = (b & t10) ^ (t4 | (a ^ c));
          }
  
          /**
          * S6 - { 7, 2,12, 5, 8, 4, 6,11,14, 9, 1,15,13, 3,10, 0 } - 15 terms.
          */
          private void Sb6(int a, int b, int c, int d)
          {
              int    t1 = ~a;
              int    t2 = a ^ d;
              int    t3 = b ^ t2;
              int    t4 = t1 | t2;
              int    t5 = c ^ t4;
              X1 = b ^ t5;
              int    t7 = t2 | X1;
              int    t8 = d ^ t7;
              int    t9 = t5 & t8;
              X2 = t3 ^ t9;
              int    t11 = t5 ^ t8;
              X0 = X2 ^ t11;
              X3 = (~t5) ^ (t3 & t11);
          }
  
          /**
          * InvS6 - {15,10, 1,13, 5, 3, 6, 0, 4, 9,14, 7, 2,12, 8,11 } - 15 terms.
          */
          private void Ib6(int a, int b, int c, int d)
          {
              int    t1 = ~a;
              int    t2 = a ^ b;
              int    t3 = c ^ t2;
              int    t4 = c | t1;
              int    t5 = d ^ t4;
              X1 = t3 ^ t5;
              int    t7 = t3 & t5;
              int    t8 = t2 ^ t7;
              int    t9 = b | t8;
              X3 = t5 ^ t9;
              int    t11 = b | X3;
              X0 = t8 ^ t11;
              X2 = (d & t1) ^ (t3 ^ t11);
          }
  
          /**
          * S7 - { 1,13,15, 0,14, 8, 2,11, 7, 4,12,10, 9, 3, 5, 6 } - 16 terms.
          */
          private void Sb7(int a, int b, int c, int d)
          {
              int    t1 = b ^ c;
              int    t2 = c & t1;
              int    t3 = d ^ t2;
              int    t4 = a ^ t3;
              int    t5 = d | t1;
  
gt:             int    t6 = t4 & t5;