Initial Commit

iTechSharp/srcbc/crypto/engines/HC128Engine.cs

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+using System;
+
+using Org.BouncyCastle.Crypto.Parameters;
+
+namespace Org.BouncyCastle.Crypto.Engines
+{
+	/**
+	* HC-128 is a software-efficient stream cipher created by Hongjun Wu. It
+	* generates keystream from a 128-bit secret key and a 128-bit initialization
+	* vector.
+	* <p>
+	* http://www.ecrypt.eu.org/stream/p3ciphers/hc/hc256_p3.pdf
+	* </p><p>
+	* It is a third phase candidate in the eStream contest, and is patent-free.
+	* No attacks are known as of today (April 2007). See
+	*
+	* http://www.ecrypt.eu.org/stream/hcp3.html
+	* </p>
+	*/
+	public class HC128Engine
+		: IStreamCipher
+	{
+		private uint[] p = new uint[512];
+		private uint[] q = new uint[512];
+		private uint cnt = 0;
+
+		private static uint F1(uint x)
+		{
+			return RotateRight(x, 7) ^ RotateRight(x, 18) ^ (x >> 3);
+		}
+
+		private static uint F2(uint x)
+		{
+			return RotateRight(x, 17) ^ RotateRight(x, 19) ^ (x >> 10);
+		}
+
+		private uint G1(uint x, uint y, uint z)
+		{
+			return (RotateRight(x, 10) ^ RotateRight(z, 23)) + RotateRight(y, 8);
+		}
+
+		private uint G2(uint x, uint y, uint z)
+		{
+			return (RotateLeft(x, 10) ^ RotateLeft(z, 23)) + RotateLeft(y, 8);
+		}
+
+		private static uint RotateLeft(uint	x, int bits)
+		{
+			return (x << bits) | (x >> -bits);
+		}
+
+		private static uint RotateRight(uint x, int bits)
+		{
+			return (x >> bits) | (x << -bits);
+		}
+
+		private uint H1(uint x)
+		{
+			return q[x & 0xFF] + q[((x >> 16) & 0xFF) + 256];
+		}
+
+		private uint H2(uint x)
+		{
+			return p[x & 0xFF] + p[((x >> 16) & 0xFF) + 256];
+		}
+
+		private static uint Mod1024(uint x)
+		{
+			return x & 0x3FF;
+		}
+
+		private static uint Mod512(uint x)
+		{
+			return x & 0x1FF;
+		}
+
+		private static uint Dim(uint x, uint y)
+		{
+			return Mod512(x - y);
+		}
+
+		private uint Step()
+		{
+			uint j = Mod512(cnt);
+			uint ret;
+			if (cnt < 512)
+			{
+				p[j] += G1(p[Dim(j, 3)], p[Dim(j, 10)], p[Dim(j, 511)]);
+				ret = H1(p[Dim(j, 12)]) ^ p[j];
+			}
+			else
+			{
+				q[j] += G2(q[Dim(j, 3)], q[Dim(j, 10)], q[Dim(j, 511)]);
+				ret = H2(q[Dim(j, 12)]) ^ q[j];
+			}
+			cnt = Mod1024(cnt + 1);
+			return ret;
+		}
+
+		private byte[] key, iv;
+		private bool initialised;
+
+		private void Init()
+		{
+			if (key.Length != 16)
+				throw new ArgumentException("The key must be 128 bit long");
+
+			cnt = 0;
+
+			uint[] w = new uint[1280];
+
+			for (int i = 0; i < 16; i++)
+			{
+				w[i >> 3] |= ((uint)key[i] << (i & 0x7));
+			}
+			Array.Copy(w, 0, w, 4, 4);
+
+			for (int i = 0; i < iv.Length && i < 16; i++)
+			{
+				w[(i >> 3) + 8] |= ((uint)iv[i] << (i & 0x7));
+			}
+			Array.Copy(w, 8, w, 12, 4);
+
+			for (uint i = 16; i < 1280; i++)
+			{
+				w[i] = F2(w[i - 2]) + w[i - 7] + F1(w[i - 15]) + w[i - 16] + i;
+			}
+
+			Array.Copy(w, 256, p, 0, 512);
+			Array.Copy(w, 768, q, 0, 512);
+
+			for (int i = 0; i < 512; i++)
+			{
+				p[i] = Step();
+			}
+			for (int i = 0; i < 512; i++)
+			{
+				q[i] = Step();
+			}
+
+			cnt = 0;
+		}
+
+		public string AlgorithmName
+		{
+			get { return "HC-128"; }
+		}
+
+		/**
+		* Initialise a HC-128 cipher.
+		*
+		* @param forEncryption whether or not we are for encryption. Irrelevant, as
+		*                      encryption and decryption are the same.
+		* @param params        the parameters required to set up the cipher.
+		* @throws ArgumentException if the params argument is
+		*                                  inappropriate (ie. the key is not 128 bit long).
+		*/
+		public void Init(
+			bool				forEncryption,
+			ICipherParameters	parameters)
+		{
+			ICipherParameters keyParam = parameters;
+
+			if (parameters is ParametersWithIV)
+			{
+				iv = ((ParametersWithIV)parameters).GetIV();
+				keyParam = ((ParametersWithIV)parameters).Parameters;
+			}
+			else
+			{
+				iv = new byte[0];
+			}
+
+			if (keyParam is KeyParameter)
+			{
+				key = ((KeyParameter)keyParam).GetKey();
+				Init();
+			}
+			else
+			{
+				throw new ArgumentException(
+					"Invalid parameter passed to HC128 init - " + parameters.GetType().Name,
+					"parameters");
+			}
+
+			initialised = true;
+		}
+
+		private byte[] buf = new byte[4];
+		private int idx = 0;
+
+		private byte GetByte()
+		{
+			if (idx == 0)
+			{
+				uint step = Step();
+				buf[3] = (byte)step;
+				step >>= 8;
+				buf[2] = (byte)step;
+				step >>= 8;
+				buf[1] = (byte)step;
+				step >>= 8;
+				buf[0] = (byte)step;
+			}
+			byte ret = buf[idx];
+			idx = idx + 1 & 0x3;
+			return ret;
+		}
+
+		public void ProcessBytes(
+			byte[]	input,
+			int		inOff,
+			int		len,
+			byte[]	output,
+			int		outOff)
+		{
+			if (!initialised)
+				throw new InvalidOperationException(AlgorithmName + " not initialised");
+			if ((inOff + len) > input.Length)
+				throw new DataLengthException("input buffer too short");
+			if ((outOff + len) > output.Length)
+				throw new DataLengthException("output buffer too short");
+
+			for (int i = 0; i < len; i++)
+			{
+				output[outOff + i] = (byte)(input[inOff + i] ^ GetByte());
+			}
+		}
+
+		public void Reset()
+		{
+			idx = 0;
+			Init();
+		}
+
+		public byte ReturnByte(byte input)
+		{
+			return (byte)(input ^ GetByte());
+		}
+	}
+}