module dcrypt.crypto.engines.serpent;

import dcrypt.crypto.blockcipher;
import dcrypt.util.bitmanip;

/// Test serpent engine. Test vectors generated with BouncyCastle implementation.
unittest {
	
	string[] keys = [
		x"01010101010101010101010101010101",
		x"0101010101010101010101010101010101010101",
		x"010101010101010101010101010101010101010101010101",
		x"01010101010101010101010101010101010101010101010101010101",
		x"0101010101010101010101010101010101010101010101010101010101010101",
	];
	string[] plains = [
		x"01010101010101010101010101010101",
		x"01010101010101010101010101010101",
		x"01010101010101010101010101010101",
		x"01010101010101010101010101010101",
		x"01010101010101010101010101010101",
	];
	string[] ciphers = [
		x"63fc6f65f3f71e6d99d981be6de30751",
		x"bc794e453a1b0bfd2475f2a40bf842ba",
		x"292a63c6d15db833f38b40b153cc303c",
		x"80808b4b6e93b6ff929a6105b508acbe",
		x"4827fcff24454cf889642a5bb12397ec",
	];
	
	SerpentEngine t = new SerpentEngine();
	blockCipherTest(t, keys, plains, ciphers);
}

alias BlockCipherWrapper!Serpent SerpentEngine;

/**
 * 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>
 * For full details see the <a href="http://www.cl.cam.ac.uk/~rja14/serpent.html">The Serpent home page</a>
 */
@safe
public struct Serpent
{

	public enum name = "Serpent";
	public enum blockSize = 16;

	private {
		enum ROUNDS = 32;
		enum uint PHI  = 0x9E3779B9;       // (sqrt(5) - 1) * 2**31

		uint X0, X1, X2, X3;    // registers
		uint[(ROUNDS + 1) * 4] wKey;

		bool encrypting;
		bool initialized = false;
	}

	/// Params:
	/// forEncryption = `false`: decrypt, `true`: encrypt
	/// userKey = Secret key.
	/// iv = Not used.
	void start(bool forEncryption, in ubyte[] userKey, in ubyte[] iv = null) nothrow @nogc
	{
		this.encrypting = forEncryption;
		makeWorkingKey(userKey);
		initialized = true;
	}

	public uint processBlock(in ubyte[]  input, ubyte[]  output) nothrow @nogc
	in {
		assert(initialized, "Serpent engine not initialized");
		assert(blockSize<=input.length, "input buffer too short");
		assert(blockSize<=output.length, "output buffer too short");
	}
	body {
		if (encrypting)
		{
			encryptBlock(input, output);
		}
		else
		{
			decryptBlock(input, output);
		}

		return blockSize;
	}

	public void reset() pure nothrow @nogc
	{
	}
	
private:
	/**
	 * Expand a user-supplied key material into a session key.
	 *
	 * Params:
	 * key  The user-key bytes (multiples of 4) to use.
	 */
	private void makeWorkingKey(in ubyte[] key) nothrow @nogc
	in {
		assert(key.length % 4 == 0, "key must be a multiple of 4 bytes");
	}
	body {
		//
		// pad key to 256 bits
		//
		uint[16]   kPad;
		size_t     off = 0;
		uint     length = 0;

		for (off = key.length - 4; off > 0; off -= 4)
		{
			kPad[length++] = bytesToWord(key[off..$]);
		}

		if (off == 0)
		{
			kPad[length++] = bytesToWord(key);
			if (length < 8)
			{
				kPad[length] = 1;
			}
		}
		else
		{
			assert(false, "key must be a multiple of 4 bytes");
		}

		//
		// expand the padded key up to 33 x 128 bits of key material
		//
		enum amount = (ROUNDS + 1) * 4;
		alias wKey w;

		//
		// compute w0 to w7 from w-8 to w-1
		//
		foreach (i;8..16)
		{
			kPad[i] = rotateLeft(kPad[i - 8] ^ kPad[i - 5] ^ kPad[i - 3] ^ kPad[i - 1] ^ PHI ^ (i - 8), 11);
		}

		w[0..8] = kPad[8..16];

		//
		// compute w8 to w136
		//
		foreach(i;8..amount)
		{
			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;
	}

	@nogc
	pure nothrow uint bytesToWord(in ubyte[]  src)
	{
		return (((src[0]) << 24) | ((src[1]) <<  16) |
			((src[2]) << 8) | ((src[3])));
	}

	@nogc
	pure nothrow void wordToBytes(uint word, ubyte[]  dst)
	{
		dst[3] = cast(ubyte)(word);
		dst[2] = cast(ubyte)(word >>> 8);
		dst[1] = cast(ubyte)(word >>> 16);
		dst[0]     = cast(ubyte)(word >>> 24);
	}

	/**
	 * Encrypt one block of plaintext.
	 *
	 */
	private void encryptBlock(in ubyte[]  input, ubyte[]  output) nothrow @nogc
	{
		X3 = bytesToWord(input[0..4]);
		X2 = bytesToWord(input[4..8]);
		X1 = bytesToWord(input[8..12]);
		X0 = bytesToWord(input[12..16]);

		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, output[0..4]);
		wordToBytes(wKey[130] ^ X2, output[4..8]);
		wordToBytes(wKey[129] ^ X1, output[8..12]);
		wordToBytes(wKey[128] ^ X0, output[12..16]);
	}

	/**
	 * Decrypt one block of ciphertext.
	 *
	 */
	private void decryptBlock(in ubyte[]  input, ubyte[]  output) nothrow @nogc
	{
		X3 = wKey[131] ^ bytesToWord(input[0..4]);
		X2 = wKey[130] ^ bytesToWord(input[4..8]);
		X1 = wKey[129] ^ bytesToWord(input[8..12]);
		X0 = wKey[128] ^ bytesToWord(input[12..16]);

		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], output[0..4]);
		wordToBytes(X2 ^ wKey[2], output[4..8]);
		wordToBytes(X1 ^ wKey[1], output[8..12]);
		wordToBytes(X0 ^ wKey[0], output[12..16]);
	}

	/**
	 * 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/
	 */

	/* Partially optimised Serpent S Box boolean 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.
	 */
	nothrow @nogc {
		void sb0(uint a, uint b, uint c, uint d)
		{
			uint    t1 = a ^ d;
			uint    t3 = c ^ t1;
			uint    t4 = b ^ t3;
			X3 = (a & d) ^ t4;
			uint    t7 = a ^ (b & t1);
			X2 = t4 ^ (c | t7);
			uint    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.
		 */ 
		void ib0(uint a, uint b, uint c, uint d)
		{
			uint    t1 = ~a;
			uint    t2 = a ^ b;
			uint    t4 = d ^ (t1 | t2);
			uint    t5 = c ^ t4;
			X2 = t2 ^ t5;
			uint    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.
		 */
		void sb1(uint a, uint b, uint c, uint d) 
		{
			uint    t2 = b ^ (~a);
			uint    t5 = c ^ (a | t2);
			X2 = d ^ t5;
			uint    t7 = b ^ (d | t2);
			uint    t8 = t2 ^ X2;
			X3 = t8 ^ (t5 & t7);
			uint    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.
		 */
		void ib1(uint a, uint b, uint c, uint d)
		{
			uint    t1 = b ^ d;
			uint    t3 = a ^ (b & t1);
			uint    t4 = t1 ^ t3;
			X3 = c ^ t4;
			uint    t7 = b ^ (t1 & t3);
			uint    t8 = X3 | t7;
			X1 = t3 ^ t8;
			uint    t10 = ~X1;
			uint    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.
		 */
		void sb2(uint a, uint b, uint c, uint d) 
		{
			uint    t1 = ~a;
			uint    t2 = b ^ d;
			uint    t3 = c & t1;
			X0 = t2 ^ t3;
			uint    t5 = c ^ t1;
			uint    t6 = c ^ X0;
			uint    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.
		 */
		void ib2(uint a, uint b, uint c, uint d)
		{
			uint    t1 = b ^ d;
			uint    t2 = ~t1;
			uint    t3 = a ^ c;
			uint    t4 = c ^ t1;
			uint    t5 = b & t4;
			X0 = t3 ^ t5;
			uint    t7 = a | t2;
			uint    t8 = d ^ t7;
			uint    t9 = t3 | t8;
			X3 = t1 ^ t9;
			uint    t11 = ~t4;
			uint    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.
		 */
		void sb3(uint a, uint b, uint c, uint d)
		{
			uint    t1 = a ^ b;
			uint    t2 = a & c;
			uint    t3 = a | d;
			uint    t4 = c ^ d;
			uint    t5 = t1 & t3;
			uint    t6 = t2 | t5;
			X2 = t4 ^ t6;
			uint    t8 = b ^ t3;
			uint    t9 = t6 ^ t8;
			uint    t10 = t4 & t9;
			X0 = t1 ^ t10;
			uint    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
		 */
		void ib3(uint a, uint b, uint c, uint d) 
		{
			uint    t1 = a | b;
			uint    t2 = b ^ c;
			uint    t3 = b & t2;
			uint    t4 = a ^ t3;
			uint    t5 = c ^ t4;
			uint    t6 = d | t4;
			X0 = t2 ^ t6;
			uint    t8 = t2 | t6;
			uint    t9 = d ^ t8;
			X2 = t5 ^ t9;
			uint    t11 = t1 ^ t9;
			uint    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.
		 */
		void sb4(uint a, uint b, uint c, uint d)
		{
			uint    t1 = a ^ d;
			uint    t2 = d & t1;
			uint    t3 = c ^ t2;
			uint    t4 = b | t3;
			X3 = t1 ^ t4;
			uint    t6 = ~b;
			uint    t7 = t1 | t6;
			X0 = t3 ^ t7;
			uint    t9 = a & X0;
			uint    t10 = t1 ^ t6;
			uint    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.
		 */
		void ib4(uint a, uint b, uint c, uint d)
		{
			uint    t1 = c | d;
			uint    t2 = a & t1;
			uint    t3 = b ^ t2;
			uint    t4 = a & t3;
			uint    t5 = c ^ t4;
			X1 = d ^ t5;
			uint    t7 = ~a;
			uint    t8 = t5 & X1;
			X3 = t3 ^ t8;
			uint    t10 = X1 | t7;
			uint    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.
		 */
		void sb5(uint a, uint b, uint c, uint d)
		{
			uint    t1 = ~a;
			uint    t2 = a ^ b;
			uint    t3 = a ^ d;
			uint    t4 = c ^ t1;
			uint    t5 = t2 | t3;
			X0 = t4 ^ t5;
			uint    t7 = d & X0;
			uint    t8 = t2 ^ X0;
			X1 = t7 ^ t8;
			uint    t10 = t1 | X0;
			uint    t11 = t2 | t7;
			uint    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.
		 */
		void ib5(uint a, uint b, uint c, uint d)
		{
			uint    t1 = ~c;
			uint    t2 = b & t1;
			uint    t3 = d ^ t2;
			uint    t4 = a & t3;
			uint    t5 = b ^ t1;
			X3 = t4 ^ t5;
			uint    t7 = b | X3;
			uint    t8 = a & t7;
			X1 = t3 ^ t8;
			uint    t10 = a | d;
			uint    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.
		 */
		void sb6(uint a, uint b, uint c, uint d)
		{
			uint    t1 = ~a;
			uint    t2 = a ^ d;
			uint    t3 = b ^ t2;
			uint    t4 = t1 | t2;
			uint    t5 = c ^ t4;
			X1 = b ^ t5;
			uint    t7 = t2 | X1;
			uint    t8 = d ^ t7;
			uint    t9 = t5 & t8;
			X2 = t3 ^ t9;
			uint    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.
		 */
		void ib6(uint a, uint b, uint c, uint d)
		{
			uint    t1 = ~a;
			uint    t2 = a ^ b;
			uint    t3 = c ^ t2;
			uint    t4 = c | t1;
			uint    t5 = d ^ t4;
			X1 = t3 ^ t5;
			uint    t7 = t3 & t5;
			uint    t8 = t2 ^ t7;
			uint    t9 = b | t8;
			X3 = t5 ^ t9;
			uint    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.
		 */
		void sb7(uint a, uint b, uint c, uint d)
		{
			uint    t1 = b ^ c;
			uint    t2 = c & t1;
			uint    t3 = d ^ t2;
			uint    t4 = a ^ t3;
			uint    t5 = d | t1;
			uint    t6 = t4 & t5;
			X1 = b ^ t6;
			uint    t8 = t3 | X1;
			uint    t9 = a & t4;
			X3 = t1 ^ t9;
			uint    t11 = t4 ^ t8;
			uint    t12 = X3 & t11;
			X2 = t3 ^ t12;
			X0 = (~t11) ^ (X3 & X2);
		}

		/**
		 * InvS7 - { 3, 0, 6,13, 9,14,15, 8, 5,12,11, 7,10, 1, 4, 2 } - 17 terms.
		 */
		void ib7(uint a, uint b, uint c, uint d)
		{
			uint t3 = c | (a & b);
			uint    t4 = d & (a | b);
			X3 = t3 ^ t4;
			uint    t6 = ~d;
			uint    t7 = b ^ t4;
			uint    t9 = t7 | (X3 ^ t6);
			X1 = a ^ t9;
			X0 = (c ^ t7) ^ (d | X1);
			X2 = (t3 ^ X1) ^ (X0 ^ (a & X3));
		}
		
		/**
		 * Apply the linear transformation to the register set.
		 */
		void LT()
		{
			uint x0  = rotateLeft(X0, 13);
			uint x2  = rotateLeft(X2, 3);
			uint x1  = X1 ^ x0 ^ x2 ;
			uint x3  = X3 ^ x2 ^ x0 << 3;

			X1  = rotateLeft(x1, 1);
			X3  = rotateLeft(x3, 7);
			X0  = rotateLeft(x0 ^ X1 ^ X3, 5);
			X2  = rotateLeft(x2 ^ X3 ^ (X1 << 7), 22);
		}

		/**
		 * Apply the inverse of the linear transformation to the register set.
		 */
		void inverseLT()
		{
			uint x2 = rotateRight(X2, 22) ^ X3 ^ (X1 << 7);
			uint x0 = rotateRight(X0, 5) ^ X1 ^ X3;
			uint x3 = rotateRight(X3, 7);
			uint x1 = rotateRight(X1, 1);
			X3 = x3 ^ x2 ^ x0 << 3;
			X1 = x1 ^ x0 ^ x2;
			X2 = rotateRight(x2, 3);
			X0 = rotateRight(x0, 13);
		}
	}
}