Port of Threefish implementation from bc-java.

All block sizes (256/5124/1024) and unit tests.

8 files changed, 1737 insertions, 1 deletions

diff --git a/crypto/crypto.mdp b/crypto/crypto.mdp
index 8152a40a9..b9ec2f9c2 100644
--- a/crypto/crypto.mdp
+++ b/crypto/crypto.mdp
@@ -2297,6 +2297,11 @@
     <File subtype="Code" buildaction="Compile" name="src/bcpg/sig/RevocationReason.cs" />
     <File subtype="Code" buildaction="Compile" name="src/bcpg/sig/RevocationReasonTags.cs" />
     <File subtype="Code" buildaction="Compile" name="src/bcpg/sig/RevocationKeyTags.cs" />
+    <File subtype="Code" buildaction="Compile" name="src/crypto/engines/ThreefishEngine.cs" />
+    <File subtype="Code" buildaction="Compile" name="src/crypto/parameters/TweakableBlockCipherParameters.cs" />
+    <File subtype="Code" buildaction="Compile" name="test/src/crypto/test/Threefish256Test.cs" />
+    <File subtype="Code" buildaction="Compile" name="test/src/crypto/test/Threefish512Test.cs" />
+    <File subtype="Code" buildaction="Compile" name="test/src/crypto/test/Threefish1024Test.cs" />
   </Contents>
   <References>
     <ProjectReference type="Assembly" localcopy="True" refto="test/lib/nunit.core.dll" />
diff --git a/crypto/src/crypto/engines/ThreefishEngine.cs b/crypto/src/crypto/engines/ThreefishEngine.cs
new file mode 100644
index 000000000..3d4ee8835
--- /dev/null
+++ b/crypto/src/crypto/engines/ThreefishEngine.cs
@@ -0,0 +1,1491 @@
+using System;
+
+using Org.BouncyCastle.Crypto.Parameters;
+using Org.BouncyCastle.Crypto.Utilities;
+using Org.BouncyCastle.Utilities.Encoders;
+
+namespace Org.BouncyCastle.Crypto.Engines
+{
+
+	/// <summary>
+	/// Implementation of the Threefish tweakable large block cipher in 256, 512 and 1024 bit block
+	/// sizes.
+	/// </summary>
+	/// <remarks>
+	/// This is the 1.3 version of Threefish defined in the Skein hash function submission to the NIST
+	/// SHA-3 competition in October 2010.
+	/// <p/>
+	/// Threefish was designed by Niels Ferguson - Stefan Lucks - Bruce Schneier - Doug Whiting - Mihir
+	/// Bellare - Tadayoshi Kohno - Jon Callas - Jesse Walker.
+	/// <p/>
+	/// This implementation inlines all round functions, unrolls 8 rounds, and uses 1.2k of static tables
+	/// to speed up key schedule injection. <br>
+	/// 2 x block size state is retained by each cipher instance.
+	/// </remarks>
+	public class ThreefishEngine
+		: IBlockCipher
+	{
+		/// <summary>
+		/// 256 bit block size - Threefish-256
+		/// </summary>
+		public const int BLOCKSIZE_256 = 256;
+		/// <summary>
+		/// 512 bit block size - Threefish-512
+		/// </summary>
+		public const int BLOCKSIZE_512 = 512;
+		/// <summary>
+		/// 1024 bit block size - Threefish-1024
+		/// </summary>
+		public const int BLOCKSIZE_1024 = 1024;
+
+		/**
+	     * Size of the tweak in bytes (always 128 bit/16 bytes)
+	     */
+		private const int TWEAK_SIZE_BYTES = 16;
+		private const int TWEAK_SIZE_WORDS = TWEAK_SIZE_BYTES / 8;
+
+		/**
+	     * Rounds in Threefish-256
+	     */
+		private const int ROUNDS_256 = 72;
+		/**
+	     * Rounds in Threefish-512
+	     */
+		private const int ROUNDS_512 = 72;
+		/**
+	     * Rounds in Threefish-1024
+	     */
+		private const int ROUNDS_1024 = 80;
+
+		/**
+	     * Max rounds of any of the variants
+	     */
+		private const int MAX_ROUNDS = ROUNDS_1024;
+
+		/**
+	     * Key schedule parity constant
+	     */
+		private const ulong C_240 = 0x1BD11BDAA9FC1A22L;
+
+		/* Pre-calculated modulo arithmetic tables for key schedule lookups */
+		private static readonly int[] MOD9 = new int[MAX_ROUNDS];
+		private static readonly int[] MOD17 = new int[MOD9.Length];
+		private static readonly int[] MOD5 = new int[MOD9.Length];
+		private static readonly int[] MOD3 = new int[MOD9.Length];
+
+		static ThreefishEngine()
+		{
+			for (int i = 0; i < MOD9.Length; i++)
+			{
+				MOD17[i] = i % 17;
+				MOD9[i] = i % 9;
+				MOD5[i] = i % 5;
+				MOD3[i] = i % 3;
+			}
+		}
+
+		/**
+	     * Block size in bytes
+	     */
+		private readonly int blocksizeBytes;
+
+		/**
+	     * Block size in 64 bit words
+	     */
+		private readonly int blocksizeWords;
+
+		/**
+	     * Buffer for byte oriented processBytes to call internal word API
+	     */
+		private readonly ulong[] currentBlock;
+
+		/**
+	     * Tweak bytes (2 byte t1,t2, calculated t3 and repeat of t1,t2 for modulo free lookup
+	     */
+		private readonly ulong[] t = new ulong[5];
+
+		/**
+	     * Key schedule words
+	     */
+		private readonly ulong[] kw;
+
+		/**
+	     * The internal cipher implementation (varies by blocksize)
+	     */
+		private readonly ThreefishCipher cipher;
+
+		private bool forEncryption;
+
+		/// <summary>
+		/// Constructs a new Threefish cipher, with a specified block size.
+		/// </summary>
+		/// <param name="blocksizeBits">the block size in bits, one of <see cref="BLOCKSIZE_256"/>, <see cref="BLOCKSIZE_512"/>,
+		///                      <see cref="BLOCKSIZE_1024"/> .</param>
+		public ThreefishEngine(int blocksizeBits)
+		{
+			this.blocksizeBytes = (blocksizeBits / 8);
+			this.blocksizeWords = (this.blocksizeBytes / 8);
+			this.currentBlock = new ulong[blocksizeWords];
+
+			/*
+	         * Provide room for original key words, extended key word and repeat of key words for modulo
+	         * free lookup of key schedule words.
+	         */
+			this.kw = new ulong[2 * blocksizeWords + 1];
+
+			switch (blocksizeBits)
+			{
+				case BLOCKSIZE_256:
+				cipher = new Threefish256Cipher(kw, t);
+				break;
+				case BLOCKSIZE_512:
+				cipher = new Threefish512Cipher(kw, t);
+				break;
+				case BLOCKSIZE_1024:
+				cipher = new Threefish1024Cipher(kw, t);
+				break;
+				default:
+				throw new ArgumentException(
+					"Invalid blocksize - Threefish is defined with block size of 256, 512, or 1024 bits");
+			}
+		}
+
+		/// <summary>
+		/// Initialise the engine.
+		/// </summary>
+		/// <param name="forEncryption">Initialise for encryption if true, for decryption if false.</param>
+		/// <param name="parameters">an instance of <see cref="TweakableBlockCipherParameters"/> or <see cref="KeyParameter"/> (to
+		///               use a 0 tweak)</param>
+		public void Init(bool forEncryption, ICipherParameters parameters)
+		{
+			byte[] keyBytes;
+			byte[] tweakBytes;
+
+			if (parameters is TweakableBlockCipherParameters)
+			{
+				TweakableBlockCipherParameters tParams = (TweakableBlockCipherParameters)parameters;
+				keyBytes = tParams.Key.GetKey();
+				tweakBytes = tParams.Tweak;
+			}
+			else if (parameters is KeyParameter)
+			{
+				keyBytes = ((KeyParameter)parameters).GetKey();
+				tweakBytes = null;
+			}
+			else
+			{
+				throw new ArgumentException("Invalid parameter passed to Threefish init - "
+				                            + parameters.GetType().Name);
+			}
+
+			ulong[] keyWords = null;
+			ulong[] tweakWords = null;
+
+			if (keyBytes != null)
+			{
+				if (keyBytes.Length != this.blocksizeBytes)
+				{
+					throw new ArgumentException("Threefish key must be same size as block (" + blocksizeBytes
+					                            + " bytes)");
+				}
+				keyWords = new ulong[blocksizeWords];
+				for (int i = 0; i < keyWords.Length; i++)
+				{
+					keyWords[i] = BytesToWord(keyBytes, i * 8);
+				}
+			}
+			if (tweakBytes != null)
+			{
+				if (tweakBytes.Length != TWEAK_SIZE_BYTES)
+				{
+					throw new ArgumentException("Threefish tweak must be " + TWEAK_SIZE_BYTES + " bytes");
+				}
+				tweakWords = new ulong[]{BytesToWord(tweakBytes, 0), BytesToWord(tweakBytes, 8)};
+			}
+			Init(forEncryption, keyWords, tweakWords);
+		}
+
+		/// <summary>
+		/// Initialise the engine, specifying the key and tweak directly.
+		/// </summary>
+		/// <param name="forEncryption">the cipher mode.</param>
+		/// <param name="key">the words of the key, or <code>null</code> to use the current key.</param>
+		/// <param name="tweak">the 2 word (128 bit) tweak, or <code>null</code> to use the current tweak.</param>
+		internal void Init(bool forEncryption, ulong[] key, ulong[] tweak)
+		{
+			this.forEncryption = forEncryption;
+			if (key != null)
+			{
+				SetKey(key);
+			}
+			if (tweak != null)
+			{
+				SetTweak(tweak);
+			}
+		}
+
+		private void SetKey(ulong[] key)
+		{
+			if (key.Length != this.blocksizeWords)
+			{
+				throw new ArgumentException("Threefish key must be same size as block (" + blocksizeWords
+				                            + " words)");
+			}
+
+			/*
+	         * Full subkey schedule is deferred to execution to avoid per cipher overhead (10k for 512,
+	         * 20k for 1024).
+	         * 
+	         * Key and tweak word sequences are repeated, and static MOD17/MOD9/MOD5/MOD3 calculations
+	         * used, to avoid expensive mod computations during cipher operation.
+	         */
+
+			ulong knw = C_240;
+			for (int i = 0; i < blocksizeWords; i++)
+			{
+				kw[i] = key[i];
+				knw = knw ^ kw[i];
+			}
+			kw[blocksizeWords] = knw;
+			Array.Copy(kw, 0, kw, blocksizeWords + 1, blocksizeWords);
+		}
+
+		private void SetTweak(ulong[] tweak)
+		{
+			if (tweak.Length != TWEAK_SIZE_WORDS)
+			{
+				throw new ArgumentException("Tweak must be " + TWEAK_SIZE_WORDS + " words.");
+			}
+
+			/*
+	         * Tweak schedule partially repeated to avoid mod computations during cipher operation
+	         */
+			t[0] = tweak[0];
+			t[1] = tweak[1];
+			t[2] = t[0] ^ t[1];
+			t[3] = t[0];
+			t[4] = t[1];
+		}
+
+		public string AlgorithmName
+		{
+			get { return "Threefish-" + (blocksizeBytes * 8); }
+		}
+
+		public bool IsPartialBlockOkay
+		{
+			get { return false; }
+		}
+
+		public int GetBlockSize()
+		{
+			return blocksizeBytes;
+		}
+
+		public void Reset()
+		{
+		}
+
+		public int ProcessBlock(byte[] inBytes, int inOff, byte[] outBytes, int outOff)
+		{
+			if ((outOff + blocksizeBytes) > outBytes.Length)
+			{
+				throw new DataLengthException("Output buffer too short");
+			}
+
+			if ((inOff + blocksizeBytes) > inBytes.Length)
+			{
+				throw new DataLengthException("Input buffer too short");
+			}
+
+			for (int i = 0; i < blocksizeBytes; i += 8)
+			{
+				currentBlock[i >> 3] = BytesToWord(inBytes, inOff + i);
+			}
+			ProcessBlock(this.currentBlock, this.currentBlock);
+			for (int i = 0; i < blocksizeBytes; i += 8)
+			{
+				WordToBytes(this.currentBlock[i >> 3], outBytes, outOff + i);
+			}
+
+			return blocksizeBytes;
+		}
+
+		/// <summary>
+		/// Process a block of data represented as 64 bit words.
+		/// </summary>
+		/// <returns>the number of 8 byte words processed (which will be the same as the block size).</returns>
+		/// <param name="inWords">a block sized buffer of words to process.</param>
+		/// <param name="outWords">a block sized buffer of words to receive the output of the operation.</param>
+		/// <exception cref="DataLengthException">if either the input or output is not block sized</exception>
+		/// <exception cref="InvalidOperationException">if this engine is not initialised</exception>
+		internal int ProcessBlock(ulong[] inWords, ulong[] outWords)
+		{
+			if (kw[blocksizeWords] == 0)
+			{
+				throw new InvalidOperationException("Threefish engine not initialised");
+			}
+
+			if (inWords.Length != blocksizeWords)
+			{
+				throw new DataLengthException("Input buffer too short");
+			}
+			if (outWords.Length != blocksizeWords)
+			{
+				throw new DataLengthException("Output buffer too short");
+			}
+
+			if (forEncryption)
+			{
+				cipher.EncryptBlock(inWords, outWords);
+			}
+			else
+			{
+				cipher.DecryptBlock(inWords, outWords);
+			}
+
+			return blocksizeWords;
+		}
+
+		/// <summary>
+		/// Read a single 64 bit word from input in LSB first order.
+		/// </summary>
+		internal static ulong BytesToWord(byte[] bytes, int off)
+		{
+			if ((off + 8) > bytes.Length)
+			{
+				// Help the JIT avoid index checks
+				throw new ArgumentException();
+			}
+
+			ulong word = 0;
+			int index = off;
+
+			word = (bytes[index++] & 0xffUL);
+			word |= (bytes[index++] & 0xffUL) << 8;
+			word |= (bytes[index++] & 0xffUL) << 16;
+			word |= (bytes[index++] & 0xffUL) << 24;
+			word |= (bytes[index++] & 0xffUL) << 32;
+			word |= (bytes[index++] & 0xffUL) << 40;
+			word |= (bytes[index++] & 0xffUL) << 48;
+			word |= (bytes[index++] & 0xffUL) << 56;
+
+			return word;
+		}
+
+		/// <summary>
+		/// Write a 64 bit word to output in LSB first order.
+		/// </summary>
+		internal static void WordToBytes(ulong word, byte[] bytes, int off)
+		{
+			if ((off + 8) > bytes.Length)
+			{
+				// Help the JIT avoid index checks
+				throw new ArgumentException();
+			}
+			int index = off;
+
+			bytes[index++] = (byte)word;
+			bytes[index++] = (byte)(word >> 8);
+			bytes[index++] = (byte)(word >> 16);
+			bytes[index++] = (byte)(word >> 24);
+			bytes[index++] = (byte)(word >> 32);
+			bytes[index++] = (byte)(word >> 40);
+			bytes[index++] = (byte)(word >> 48);
+			bytes[index++] = (byte)(word >> 56);
+		}
+
+		/**
+	     * Rotate left + xor part of the mix operation.
+	     */
+		private static ulong RotlXor(ulong x, int n, ulong xor)
+		{
+			return ((x << n) | (x >> (64 - n))) ^ xor;
+		}
+
+		/**
+	     * Rotate xor + rotate right part of the unmix operation.
+	     */
+		private static ulong XorRotr(ulong x, int n, ulong xor)
+		{
+			ulong xored = x ^ xor;
+			return (xored >> n) | (xored << (64 - n));
+		}
+
+		private abstract class ThreefishCipher
+		{
+			/**
+	         * The extended + repeated tweak words
+	         */
+			protected readonly ulong[] t;
+			/**
+	         * The extended + repeated key words
+	         */
+			protected readonly ulong[] kw;
+
+			protected ThreefishCipher(ulong[] kw, ulong[] t)
+			{
+				this.kw = kw;
+				this.t = t;
+			}
+
+			internal abstract void EncryptBlock(ulong[] block, ulong[] outWords);
+
+			internal abstract void DecryptBlock(ulong[] block, ulong[] outWords);
+
+		}
+
+		private sealed class Threefish256Cipher
+			: ThreefishCipher
+		{
+			/**
+	         * Mix rotation constants defined in Skein 1.3 specification
+	         */
+			private const int ROTATION_0_0 = 14, ROTATION_0_1 = 16;
+			private const int ROTATION_1_0 = 52, ROTATION_1_1 = 57;
+			private const int ROTATION_2_0 = 23, ROTATION_2_1 = 40;
+			private const int ROTATION_3_0 = 5, ROTATION_3_1 = 37;
+
+			private const int ROTATION_4_0 = 25, ROTATION_4_1 = 33;
+			private const int ROTATION_5_0 = 46, ROTATION_5_1 = 12;
+			private const int ROTATION_6_0 = 58, ROTATION_6_1 = 22;
+			private const int ROTATION_7_0 = 32, ROTATION_7_1 = 32;
+
+			public Threefish256Cipher(ulong[] kw, ulong[] t)
+				: base(kw, t)
+			{
+			}
+
+			internal override void EncryptBlock(ulong[] block, ulong[] outWords)
+			{
+				ulong[] kw = this.kw;
+				ulong[] t = this.t;
+				int[] mod5 = MOD5;
+				int[] mod3 = MOD3;
+
+				/* Help the JIT avoid index bounds checks */
+				if (kw.Length != 9)
+				{
+					throw new ArgumentException();
+				}
+				if (t.Length != 5)
+				{
+					throw new ArgumentException();
+				}
+
+				/*
+	             * Read 4 words of plaintext data, not using arrays for cipher state
+	             */
+				ulong b0 = block[0];
+				ulong b1 = block[1];
+				ulong b2 = block[2];
+				ulong b3 = block[3];
+
+				/*
+	             * First subkey injection.
+	             */
+				b0 += kw[0];
+				b1 += kw[1] + t[0];
+				b2 += kw[2] + t[1];
+				b3 += kw[3];
+
+				/*
+	             * Rounds loop, unrolled to 8 rounds per iteration.
+	             * 
+	             * Unrolling to multiples of 4 avoids the mod 4 check for key injection, and allows
+	             * inlining of the permutations, which cycle every of 2 rounds (avoiding array
+	             * index/lookup).
+	             * 
+	             * Unrolling to multiples of 8 avoids the mod 8 rotation constant lookup, and allows
+	             * inlining constant rotation values (avoiding array index/lookup).
+	             */
+
+				for (int d = 1; d < (ROUNDS_256 / 4); d += 2)
+				{
+					int dm5 = mod5[d];
+					int dm3 = mod3[d];
+
+					/*
+	                 * 4 rounds of mix and permute.
+	                 * 
+	                 * Permute schedule has a 2 round cycle, so permutes are inlined in the mix
+	                 * operations in each 4 round block.
+	                 */
+					b1 = RotlXor(b1, ROTATION_0_0, b0 += b1);
+					b3 = RotlXor(b3, ROTATION_0_1, b2 += b3);
+
+					b3 = RotlXor(b3, ROTATION_1_0, b0 += b3);
+					b1 = RotlXor(b1, ROTATION_1_1, b2 += b1);
+
+					b1 = RotlXor(b1, ROTATION_2_0, b0 += b1);
+					b3 = RotlXor(b3, ROTATION_2_1, b2 += b3);
+
+					b3 = RotlXor(b3, ROTATION_3_0, b0 += b3);
+					b1 = RotlXor(b1, ROTATION_3_1, b2 += b1);
+
+					/*
+	                 * Subkey injection for first 4 rounds.
+	                 */
+					b0 += kw[dm5];
+					b1 += kw[dm5 + 1] + t[dm3];
+					b2 += kw[dm5 + 2] + t[dm3 + 1];
+					b3 += kw[dm5 + 3] + (uint)d;
+
+					/*
+	                 * 4 more rounds of mix/permute
+	                 */
+					b1 = RotlXor(b1, ROTATION_4_0, b0 += b1);
+					b3 = RotlXor(b3, ROTATION_4_1, b2 += b3);
+
+					b3 = RotlXor(b3, ROTATION_5_0, b0 += b3);
+					b1 = RotlXor(b1, ROTATION_5_1, b2 += b1);
+
+					b1 = RotlXor(b1, ROTATION_6_0, b0 += b1);
+					b3 = RotlXor(b3, ROTATION_6_1, b2 += b3);
+
+					b3 = RotlXor(b3, ROTATION_7_0, b0 += b3);
+					b1 = RotlXor(b1, ROTATION_7_1, b2 += b1);
+
+					/*
+	                 * Subkey injection for next 4 rounds.
+	                 */
+					b0 += kw[dm5 + 1];
+					b1 += kw[dm5 + 2] + t[dm3 + 1];
+					b2 += kw[dm5 + 3] + t[dm3 + 2];
+					b3 += kw[dm5 + 4] + (uint)d + 1;
+				}
+
+				/*
+	             * Output cipher state.
+	             */
+				outWords[0] = b0;
+				outWords[1] = b1;
+				outWords[2] = b2;
+				outWords[3] = b3;
+			}
+
+			internal override void DecryptBlock(ulong[] block, ulong[] state)
+			{
+				ulong[] kw = this.kw;
+				ulong[] t = this.t;
+				int[] mod5 = MOD5;
+				int[] mod3 = MOD3;
+
+				/* Help the JIT avoid index bounds checks */
+				if (kw.Length != 9)
+				{
+					throw new ArgumentException();
+				}
+				if (t.Length != 5)
+				{
+					throw new ArgumentException();
+				}
+
+				ulong b0 = block[0];
+				ulong b1 = block[1];
+				ulong b2 = block[2];
+				ulong b3 = block[3];
+
+				for (int d = (ROUNDS_256 / 4) - 1; d >= 1; d -= 2)
+				{
+					int dm5 = mod5[d];
+					int dm3 = mod3[d];
+
+					/* Reverse key injection for second 4 rounds */
+					b0 -= kw[dm5 + 1];
+					b1 -= kw[dm5 + 2] + t[dm3 + 1];
+					b2 -= kw[dm5 + 3] + t[dm3 + 2];
+					b3 -= kw[dm5 + 4] + (uint)d + 1;
+
+					/* Reverse second 4 mix/permute rounds */
+
+					b3 = XorRotr(b3, ROTATION_7_0, b0);
+					b0 -= b3;
+					b1 = XorRotr(b1, ROTATION_7_1, b2);
+					b2 -= b1;
+
+					b1 = XorRotr(b1, ROTATION_6_0, b0);
+					b0 -= b1;
+					b3 = XorRotr(b3, ROTATION_6_1, b2);
+					b2 -= b3;
+
+					b3 = XorRotr(b3, ROTATION_5_0, b0);
+					b0 -= b3;
+					b1 = XorRotr(b1, ROTATION_5_1, b2);
+					b2 -= b1;
+
+					b1 = XorRotr(b1, ROTATION_4_0, b0);
+					b0 -= b1;
+					b3 = XorRotr(b3, ROTATION_4_1, b2);
+					b2 -= b3;
+
+					/* Reverse key injection for first 4 rounds */
+					b0 -= kw[dm5];
+					b1 -= kw[dm5 + 1] + t[dm3];
+					b2 -= kw[dm5 + 2] + t[dm3 + 1];
+					b3 -= kw[dm5 + 3] + (uint)d;
+
+					/* Reverse first 4 mix/permute rounds */
+					b3 = XorRotr(b3, ROTATION_3_0, b0);
+					b0 -= b3;
+					b1 = XorRotr(b1, ROTATION_3_1, b2);
+					b2 -= b1;
+
+					b1 = XorRotr(b1, ROTATION_2_0, b0);
+					b0 -= b1;
+					b3 = XorRotr(b3, ROTATION_2_1, b2);
+					b2 -= b3;
+
+					b3 = XorRotr(b3, ROTATION_1_0, b0);
+					b0 -= b3;
+					b1 = XorRotr(b1, ROTATION_1_1, b2);
+					b2 -= b1;
+
+					b1 = XorRotr(b1, ROTATION_0_0, b0);
+					b0 -= b1;
+					b3 = XorRotr(b3, ROTATION_0_1, b2);
+					b2 -= b3;
+				}
+
+				/*
+	             * First subkey uninjection.
+	             */
+				b0 -= kw[0];
+				b1 -= kw[1] + t[0];
+				b2 -= kw[2] + t[1];
+				b3 -= kw[3];
+
+				/*
+	             * Output cipher state.
+	             */
+				state[0] = b0;
+				state[1] = b1;
+				state[2] = b2;
+				state[3] = b3;
+			}
+
+		}
+
+		private sealed class Threefish512Cipher
+			: ThreefishCipher
+		{
+			/**
+	         * Mix rotation constants defined in Skein 1.3 specification
+	         */
+			private const int ROTATION_0_0 = 46, ROTATION_0_1 = 36, ROTATION_0_2 = 19, ROTATION_0_3 = 37;
+			private const int ROTATION_1_0 = 33, ROTATION_1_1 = 27, ROTATION_1_2 = 14, ROTATION_1_3 = 42;
+			private const int ROTATION_2_0 = 17, ROTATION_2_1 = 49, ROTATION_2_2 = 36, ROTATION_2_3 = 39;
+			private const int ROTATION_3_0 = 44, ROTATION_3_1 = 9, ROTATION_3_2 = 54, ROTATION_3_3 = 56;
+
+			private const int ROTATION_4_0 = 39, ROTATION_4_1 = 30, ROTATION_4_2 = 34, ROTATION_4_3 = 24;
+			private const int ROTATION_5_0 = 13, ROTATION_5_1 = 50, ROTATION_5_2 = 10, ROTATION_5_3 = 17;
+			private const int ROTATION_6_0 = 25, ROTATION_6_1 = 29, ROTATION_6_2 = 39, ROTATION_6_3 = 43;
+			private const int ROTATION_7_0 = 8, ROTATION_7_1 = 35, ROTATION_7_2 = 56, ROTATION_7_3 = 22;
+
+			internal Threefish512Cipher(ulong[] kw, ulong[] t)
+				: base(kw, t)
+			{
+			}
+
+			internal override void EncryptBlock(ulong[] block, ulong[] outWords)
+			{
+				ulong[] kw = this.kw;
+				ulong[] t = this.t;
+				int[] mod9 = MOD9;
+				int[] mod3 = MOD3;
+
+				/* Help the JIT avoid index bounds checks */
+				if (kw.Length != 17)
+				{
+					throw new ArgumentException();
+				}
+				if (t.Length != 5)
+				{
+					throw new ArgumentException();
+				}
+
+				/*
+	             * Read 8 words of plaintext data, not using arrays for cipher state
+	             */
+				ulong b0 = block[0];
+				ulong b1 = block[1];
+				ulong b2 = block[2];
+				ulong b3 = block[3];
+				ulong b4 = block[4];
+				ulong b5 = block[5];
+				ulong b6 = block[6];
+				ulong b7 = block[7];
+
+				/*
+	             * First subkey injection.
+	             */
+				b0 += kw[0];
+				b1 += kw[1];
+				b2 += kw[2];
+				b3 += kw[3];
+				b4 += kw[4];
+				b5 += kw[5] + t[0];
+				b6 += kw[6] + t[1];
+				b7 += kw[7];
+
+				/*
+	             * Rounds loop, unrolled to 8 rounds per iteration.
+	             * 
+	             * Unrolling to multiples of 4 avoids the mod 4 check for key injection, and allows
+	             * inlining of the permutations, which cycle every of 4 rounds (avoiding array
+	             * index/lookup).
+	             * 
+	             * Unrolling to multiples of 8 avoids the mod 8 rotation constant lookup, and allows
+	             * inlining constant rotation values (avoiding array index/lookup).
+	             */
+
+				for (int d = 1; d < (ROUNDS_512 / 4); d += 2)
+				{
+					int dm9 = mod9[d];
+					int dm3 = mod3[d];
+
+					/*
+	                 * 4 rounds of mix and permute.
+	                 * 
+	                 * Permute schedule has a 4 round cycle, so permutes are inlined in the mix
+	                 * operations in each 4 round block.
+	                 */
+					b1 = RotlXor(b1, ROTATION_0_0, b0 += b1);
+					b3 = RotlXor(b3, ROTATION_0_1, b2 += b3);
+					b5 = RotlXor(b5, ROTATION_0_2, b4 += b5);
+					b7 = RotlXor(b7, ROTATION_0_3, b6 += b7);
+
+					b1 = RotlXor(b1, ROTATION_1_0, b2 += b1);
+					b7 = RotlXor(b7, ROTATION_1_1, b4 += b7);
+					b5 = RotlXor(b5, ROTATION_1_2, b6 += b5);
+					b3 = RotlXor(b3, ROTATION_1_3, b0 += b3);
+
+					b1 = RotlXor(b1, ROTATION_2_0, b4 += b1);
+					b3 = RotlXor(b3, ROTATION_2_1, b6 += b3);
+					b5 = RotlXor(b5, ROTATION_2_2, b0 += b5);
+					b7 = RotlXor(b7, ROTATION_2_3, b2 += b7);
+
+					b1 = RotlXor(b1, ROTATION_3_0, b6 += b1);
+					b7 = RotlXor(b7, ROTATION_3_1, b0 += b7);
+					b5 = RotlXor(b5, ROTATION_3_2, b2 += b5);
+					b3 = RotlXor(b3, ROTATION_3_3, b4 += b3);
+
+					/*
+	                 * Subkey injection for first 4 rounds.
+	                 */
+					b0 += kw[dm9];
+					b1 += kw[dm9 + 1];
+					b2 += kw[dm9 + 2];
+					b3 += kw[dm9 + 3];
+					b4 += kw[dm9 + 4];
+					b5 += kw[dm9 + 5] + t[dm3];
+					b6 += kw[dm9 + 6] + t[dm3 + 1];
+					b7 += kw[dm9 + 7] + (uint)d;
+
+					/*
+	                 * 4 more rounds of mix/permute
+	                 */
+					b1 = RotlXor(b1, ROTATION_4_0, b0 += b1);
+					b3 = RotlXor(b3, ROTATION_4_1, b2 += b3);
+					b5 = RotlXor(b5, ROTATION_4_2, b4 += b5);
+					b7 = RotlXor(b7, ROTATION_4_3, b6 += b7);
+
+					b1 = RotlXor(b1, ROTATION_5_0, b2 += b1);
+					b7 = RotlXor(b7, ROTATION_5_1, b4 += b7);
+					b5 = RotlXor(b5, ROTATION_5_2, b6 += b5);
+					b3 = RotlXor(b3, ROTATION_5_3, b0 += b3);
+
+					b1 = RotlXor(b1, ROTATION_6_0, b4 += b1);
+					b3 = RotlXor(b3, ROTATION_6_1, b6 += b3);
+					b5 = RotlXor(b5, ROTATION_6_2, b0 += b5);
+					b7 = RotlXor(b7, ROTATION_6_3, b2 += b7);
+
+					b1 = RotlXor(b1, ROTATION_7_0, b6 += b1);
+					b7 = RotlXor(b7, ROTATION_7_1, b0 += b7);
+					b5 = RotlXor(b5, ROTATION_7_2, b2 += b5);
+					b3 = RotlXor(b3, ROTATION_7_3, b4 += b3);
+
+					/*
+	                 * Subkey injection for next 4 rounds.
+	                 */
+					b0 += kw[dm9 + 1];
+					b1 += kw[dm9 + 2];
+					b2 += kw[dm9 + 3];
+					b3 += kw[dm9 + 4];
+					b4 += kw[dm9 + 5];
+					b5 += kw[dm9 + 6] + t[dm3 + 1];
+					b6 += kw[dm9 + 7] + t[dm3 + 2];
+					b7 += kw[dm9 + 8] + (uint)d + 1;
+				}
+
+				/*
+	             * Output cipher state.
+	             */
+				outWords[0] = b0;
+				outWords[1] = b1;
+				outWords[2] = b2;
+				outWords[3] = b3;
+				outWords[4] = b4;
+				outWords[5] = b5;
+				outWords[6] = b6;
+				outWords[7] = b7;
+			}
+
+			internal override void DecryptBlock(ulong[] block, ulong[] state)
+			{
+				ulong[] kw = this.kw;
+				ulong[] t = this.t;
+				int[] mod9 = MOD9;
+				int[] mod3 = MOD3;
+
+				/* Help the JIT avoid index bounds checks */
+				if (kw.Length != 17)
+				{
+					throw new ArgumentException();
+				}
+				if (t.Length != 5)
+				{
+					throw new ArgumentException();
+				}
+
+				ulong b0 = block[0];
+				ulong b1 = block[1];
+				ulong b2 = block[2];
+				ulong b3 = block[3];
+				ulong b4 = block[4];
+				ulong b5 = block[5];
+				ulong b6 = block[6];
+				ulong b7 = block[7];
+
+				for (int d = (ROUNDS_512 / 4) - 1; d >= 1; d -= 2)
+				{
+					int dm9 = mod9[d];
+					int dm3 = mod3[d];
+
+					/* Reverse key injection for second 4 rounds */
+					b0 -= kw[dm9 + 1];
+					b1 -= kw[dm9 + 2];
+					b2 -= kw[dm9 + 3];
+					b3 -= kw[dm9 + 4];
+					b4 -= kw[dm9 + 5];
+					b5 -= kw[dm9 + 6] + t[dm3 + 1];
+					b6 -= kw[dm9 + 7] + t[dm3 + 2];
+					b7 -= kw[dm9 + 8] + (uint)d + 1;
+
+					/* Reverse second 4 mix/permute rounds */
+
+					b1 = XorRotr(b1, ROTATION_7_0, b6);
+					b6 -= b1;
+					b7 = XorRotr(b7, ROTATION_7_1, b0);
+					b0 -= b7;
+					b5 = XorRotr(b5, ROTATION_7_2, b2);
+					b2 -= b5;
+					b3 = XorRotr(b3, ROTATION_7_3, b4);
+					b4 -= b3;
+
+					b1 = XorRotr(b1, ROTATION_6_0, b4);
+					b4 -= b1;
+					b3 = XorRotr(b3, ROTATION_6_1, b6);
+					b6 -= b3;
+					b5 = XorRotr(b5, ROTATION_6_2, b0);
+					b0 -= b5;
+					b7 = XorRotr(b7, ROTATION_6_3, b2);
+					b2 -= b7;
+
+					b1 = XorRotr(b1, ROTATION_5_0, b2);
+					b2 -= b1;
+					b7 = XorRotr(b7, ROTATION_5_1, b4);
+					b4 -= b7;
+					b5 = XorRotr(b5, ROTATION_5_2, b6);
+					b6 -= b5;
+					b3 = XorRotr(b3, ROTATION_5_3, b0);
+					b0 -= b3;
+
+					b1 = XorRotr(b1, ROTATION_4_0, b0);
+					b0 -= b1;
+					b3 = XorRotr(b3, ROTATION_4_1, b2);
+					b2 -= b3;
+					b5 = XorRotr(b5, ROTATION_4_2, b4);
+					b4 -= b5;
+					b7 = XorRotr(b7, ROTATION_4_3, b6);
+					b6 -= b7;
+
+					/* Reverse key injection for first 4 rounds */
+					b0 -= kw[dm9];
+					b1 -= kw[dm9 + 1];
+					b2 -= kw[dm9 + 2];
+					b3 -= kw[dm9 + 3];
+					b4 -= kw[dm9 + 4];
+					b5 -= kw[dm9 + 5] + t[dm3];
+					b6 -= kw[dm9 + 6] + t[dm3 + 1];
+					b7 -= kw[dm9 + 7] + (uint)d;
+
+					/* Reverse first 4 mix/permute rounds */
+					b1 = XorRotr(b1, ROTATION_3_0, b6);
+					b6 -= b1;
+					b7 = XorRotr(b7, ROTATION_3_1, b0);
+					b0 -= b7;
+					b5 = XorRotr(b5, ROTATION_3_2, b2);
+					b2 -= b5;
+					b3 = XorRotr(b3, ROTATION_3_3, b4);
+					b4 -= b3;
+
+					b1 = XorRotr(b1, ROTATION_2_0, b4);
+					b4 -= b1;
+					b3 = XorRotr(b3, ROTATION_2_1, b6);
+					b6 -= b3;
+					b5 = XorRotr(b5, ROTATION_2_2, b0);
+					b0 -= b5;
+					b7 = XorRotr(b7, ROTATION_2_3, b2);
+					b2 -= b7;
+
+					b1 = XorRotr(b1, ROTATION_1_0, b2);
+					b2 -= b1;
+					b7 = XorRotr(b7, ROTATION_1_1, b4);
+					b4 -= b7;
+					b5 = XorRotr(b5, ROTATION_1_2, b6);
+					b6 -= b5;
+					b3 = XorRotr(b3, ROTATION_1_3, b0);
+					b0 -= b3;
+
+					b1 = XorRotr(b1, ROTATION_0_0, b0);
+					b0 -= b1;
+					b3 = XorRotr(b3, ROTATION_0_1, b2);
+					b2 -= b3;
+					b5 = XorRotr(b5, ROTATION_0_2, b4);
+					b4 -= b5;
+					b7 = XorRotr(b7, ROTATION_0_3, b6);
+					b6 -= b7;
+				}
+
+				/*
+	             * First subkey uninjection.
+	             */
+				b0 -= kw[0];
+				b1 -= kw[1];
+				b2 -= kw[2];
+				b3 -= kw[3];
+				b4 -= kw[4];
+				b5 -= kw[5] + t[0];
+				b6 -= kw[6] + t[1];
+				b7 -= kw[7];
+
+				/*
+	             * Output cipher state.
+	             */
+				state[0] = b0;
+				state[1] = b1;
+				state[2] = b2;
+				state[3] = b3;
+				state[4] = b4;
+				state[5] = b5;
+				state[6] = b6;
+				state[7] = b7;
+			}
+		}
+
+		private sealed class Threefish1024Cipher
+			: ThreefishCipher
+		{
+			/**
+	         * Mix rotation constants defined in Skein 1.3 specification
+	         */
+			private const int ROTATION_0_0 = 24, ROTATION_0_1 = 13, ROTATION_0_2 = 8, ROTATION_0_3 = 47;
+			private const int ROTATION_0_4 = 8, ROTATION_0_5 = 17, ROTATION_0_6 = 22, ROTATION_0_7 = 37;
+			private const int ROTATION_1_0 = 38, ROTATION_1_1 = 19, ROTATION_1_2 = 10, ROTATION_1_3 = 55;
+			private const int ROTATION_1_4 = 49, ROTATION_1_5 = 18, ROTATION_1_6 = 23, ROTATION_1_7 = 52;
+			private const int ROTATION_2_0 = 33, ROTATION_2_1 = 4, ROTATION_2_2 = 51, ROTATION_2_3 = 13;
+			private const int ROTATION_2_4 = 34, ROTATION_2_5 = 41, ROTATION_2_6 = 59, ROTATION_2_7 = 17;
+			private const int ROTATION_3_0 = 5, ROTATION_3_1 = 20, ROTATION_3_2 = 48, ROTATION_3_3 = 41;
+			private const int ROTATION_3_4 = 47, ROTATION_3_5 = 28, ROTATION_3_6 = 16, ROTATION_3_7 = 25;
+
+			private const int ROTATION_4_0 = 41, ROTATION_4_1 = 9, ROTATION_4_2 = 37, ROTATION_4_3 = 31;
+			private const int ROTATION_4_4 = 12, ROTATION_4_5 = 47, ROTATION_4_6 = 44, ROTATION_4_7 = 30;
+			private const int ROTATION_5_0 = 16, ROTATION_5_1 = 34, ROTATION_5_2 = 56, ROTATION_5_3 = 51;
+			private const int ROTATION_5_4 = 4, ROTATION_5_5 = 53, ROTATION_5_6 = 42, ROTATION_5_7 = 41;
+			private const int ROTATION_6_0 = 31, ROTATION_6_1 = 44, ROTATION_6_2 = 47, ROTATION_6_3 = 46;
+			private const int ROTATION_6_4 = 19, ROTATION_6_5 = 42, ROTATION_6_6 = 44, ROTATION_6_7 = 25;
+			private const int ROTATION_7_0 = 9, ROTATION_7_1 = 48, ROTATION_7_2 = 35, ROTATION_7_3 = 52;
+			private const int ROTATION_7_4 = 23, ROTATION_7_5 = 31, ROTATION_7_6 = 37, ROTATION_7_7 = 20;
+
+			public Threefish1024Cipher(ulong[] kw, ulong[] t)
+				: base(kw, t)
+			{
+			}
+
+			internal override void EncryptBlock(ulong[] block, ulong[] outWords)
+			{
+				ulong[] kw = this.kw;
+				ulong[] t = this.t;
+				int[] mod17 = MOD17;
+				int[] mod3 = MOD3;
+
+				/* Help the JIT avoid index bounds checks */
+				if (kw.Length != 33)
+				{
+					throw new ArgumentException();
+				}
+				if (t.Length != 5)
+				{
+					throw new ArgumentException();
+				}
+
+				/*
+	             * Read 16 words of plaintext data, not using arrays for cipher state
+	             */
+				ulong b0 = block[0];
+				ulong b1 = block[1];
+				ulong b2 = block[2];
+				ulong b3 = block[3];
+				ulong b4 = block[4];
+				ulong b5 = block[5];
+				ulong b6 = block[6];
+				ulong b7 = block[7];
+				ulong b8 = block[8];
+				ulong b9 = block[9];
+				ulong b10 = block[10];
+				ulong b11 = block[11];
+				ulong b12 = block[12];
+				ulong b13 = block[13];
+				ulong b14 = block[14];
+				ulong b15 = block[15];
+
+				/*
+	             * First subkey injection.
+	             */
+				b0 += kw[0];
+				b1 += kw[1];
+				b2 += kw[2];
+				b3 += kw[3];
+				b4 += kw[4];
+				b5 += kw[5];
+				b6 += kw[6];
+				b7 += kw[7];
+				b8 += kw[8];
+				b9 += kw[9];
+				b10 += kw[10];
+				b11 += kw[11];
+				b12 += kw[12];
+				b13 += kw[13] + t[0];
+				b14 += kw[14] + t[1];
+				b15 += kw[15];
+
+				/*
+	             * Rounds loop, unrolled to 8 rounds per iteration.
+	             * 
+	             * Unrolling to multiples of 4 avoids the mod 4 check for key injection, and allows
+	             * inlining of the permutations, which cycle every of 4 rounds (avoiding array
+	             * index/lookup).
+	             * 
+	             * Unrolling to multiples of 8 avoids the mod 8 rotation constant lookup, and allows
+	             * inlining constant rotation values (avoiding array index/lookup).
+	             */
+
+				for (int d = 1; d < (ROUNDS_1024 / 4); d += 2)
+				{
+					int dm17 = mod17[d];
+					int dm3 = mod3[d];
+
+					/*
+	                 * 4 rounds of mix and permute.
+	                 * 
+	                 * Permute schedule has a 4 round cycle, so permutes are inlined in the mix
+	                 * operations in each 4 round block.
+	                 */
+					b1 = RotlXor(b1, ROTATION_0_0, b0 += b1);
+					b3 = RotlXor(b3, ROTATION_0_1, b2 += b3);
+					b5 = RotlXor(b5, ROTATION_0_2, b4 += b5);
+					b7 = RotlXor(b7, ROTATION_0_3, b6 += b7);
+					b9 = RotlXor(b9, ROTATION_0_4, b8 += b9);
+					b11 = RotlXor(b11, ROTATION_0_5, b10 += b11);
+					b13 = RotlXor(b13, ROTATION_0_6, b12 += b13);
+					b15 = RotlXor(b15, ROTATION_0_7, b14 += b15);
+
+					b9 = RotlXor(b9, ROTATION_1_0, b0 += b9);
+					b13 = RotlXor(b13, ROTATION_1_1, b2 += b13);
+					b11 = RotlXor(b11, ROTATION_1_2, b6 += b11);
+					b15 = RotlXor(b15, ROTATION_1_3, b4 += b15);
+					b7 = RotlXor(b7, ROTATION_1_4, b10 += b7);
+					b3 = RotlXor(b3, ROTATION_1_5, b12 += b3);
+					b5 = RotlXor(b5, ROTATION_1_6, b14 += b5);
+					b1 = RotlXor(b1, ROTATION_1_7, b8 += b1);
+
+					b7 = RotlXor(b7, ROTATION_2_0, b0 += b7);
+					b5 = RotlXor(b5, ROTATION_2_1, b2 += b5);
+					b3 = RotlXor(b3, ROTATION_2_2, b4 += b3);
+					b1 = RotlXor(b1, ROTATION_2_3, b6 += b1);
+					b15 = RotlXor(b15, ROTATION_2_4, b12 += b15);
+					b13 = RotlXor(b13, ROTATION_2_5, b14 += b13);
+					b11 = RotlXor(b11, ROTATION_2_6, b8 += b11);
+					b9 = RotlXor(b9, ROTATION_2_7, b10 += b9);
+
+					b15 = RotlXor(b15, ROTATION_3_0, b0 += b15);
+					b11 = RotlXor(b11, ROTATION_3_1, b2 += b11);
+					b13 = RotlXor(b13, ROTATION_3_2, b6 += b13);
+					b9 = RotlXor(b9, ROTATION_3_3, b4 += b9);
+					b1 = RotlXor(b1, ROTATION_3_4, b14 += b1);
+					b5 = RotlXor(b5, ROTATION_3_5, b8 += b5);
+					b3 = RotlXor(b3, ROTATION_3_6, b10 += b3);
+					b7 = RotlXor(b7, ROTATION_3_7, b12 += b7);
+
+					/*
+	                 * Subkey injection for first 4 rounds.
+	                 */
+					b0 += kw[dm17];
+					b1 += kw[dm17 + 1];
+					b2 += kw[dm17 + 2];
+					b3 += kw[dm17 + 3];
+					b4 += kw[dm17 + 4];
+					b5 += kw[dm17 + 5];
+					b6 += kw[dm17 + 6];
+					b7 += kw[dm17 + 7];
+					b8 += kw[dm17 + 8];
+					b9 += kw[dm17 + 9];
+					b10 += kw[dm17 + 10];
+					b11 += kw[dm17 + 11];
+					b12 += kw[dm17 + 12];
+					b13 += kw[dm17 + 13] + t[dm3];
+					b14 += kw[dm17 + 14] + t[dm3 + 1];
+					b15 += kw[dm17 + 15] + (uint)d;
+
+					/*
+	                 * 4 more rounds of mix/permute
+	                 */
+					b1 = RotlXor(b1, ROTATION_4_0, b0 += b1);
+					b3 = RotlXor(b3, ROTATION_4_1, b2 += b3);
+					b5 = RotlXor(b5, ROTATION_4_2, b4 += b5);
+					b7 = RotlXor(b7, ROTATION_4_3, b6 += b7);
+					b9 = RotlXor(b9, ROTATION_4_4, b8 += b9);
+					b11 = RotlXor(b11, ROTATION_4_5, b10 += b11);
+					b13 = RotlXor(b13, ROTATION_4_6, b12 += b13);
+					b15 = RotlXor(b15, ROTATION_4_7, b14 += b15);
+
+					b9 = RotlXor(b9, ROTATION_5_0, b0 += b9);
+					b13 = RotlXor(b13, ROTATION_5_1, b2 += b13);
+					b11 = RotlXor(b11, ROTATION_5_2, b6 += b11);
+					b15 = RotlXor(b15, ROTATION_5_3, b4 += b15);
+					b7 = RotlXor(b7, ROTATION_5_4, b10 += b7);
+					b3 = RotlXor(b3, ROTATION_5_5, b12 += b3);
+					b5 = RotlXor(b5, ROTATION_5_6, b14 += b5);
+					b1 = RotlXor(b1, ROTATION_5_7, b8 += b1);
+
+					b7 = RotlXor(b7, ROTATION_6_0, b0 += b7);
+					b5 = RotlXor(b5, ROTATION_6_1, b2 += b5);
+					b3 = RotlXor(b3, ROTATION_6_2, b4 += b3);
+					b1 = RotlXor(b1, ROTATION_6_3, b6 += b1);
+					b15 = RotlXor(b15, ROTATION_6_4, b12 += b15);
+					b13 = RotlXor(b13, ROTATION_6_5, b14 += b13);
+					b11 = RotlXor(b11, ROTATION_6_6, b8 += b11);
+					b9 = RotlXor(b9, ROTATION_6_7, b10 += b9);
+
+					b15 = RotlXor(b15, ROTATION_7_0, b0 += b15);
+					b11 = RotlXor(b11, ROTATION_7_1, b2 += b11);
+					b13 = RotlXor(b13, ROTATION_7_2, b6 += b13);
+					b9 = RotlXor(b9, ROTATION_7_3, b4 += b9);
+					b1 = RotlXor(b1, ROTATION_7_4, b14 += b1);
+					b5 = RotlXor(b5, ROTATION_7_5, b8 += b5);
+					b3 = RotlXor(b3, ROTATION_7_6, b10 += b3);
+					b7 = RotlXor(b7, ROTATION_7_7, b12 += b7);
+
+					/*
+	                 * Subkey injection for next 4 rounds.
+	                 */
+					b0 += kw[dm17 + 1];
+					b1 += kw[dm17 + 2];
+					b2 += kw[dm17 + 3];
+					b3 += kw[dm17 + 4];
+					b4 += kw[dm17 + 5];
+					b5 += kw[dm17 + 6];
+					b6 += kw[dm17 + 7];
+					b7 += kw[dm17 + 8];
+					b8 += kw[dm17 + 9];
+					b9 += kw[dm17 + 10];
+					b10 += kw[dm17 + 11];
+					b11 += kw[dm17 + 12];
+					b12 += kw[dm17 + 13];
+					b13 += kw[dm17 + 14] + t[dm3 + 1];
+					b14 += kw[dm17 + 15] + t[dm3 + 2];
+					b15 += kw[dm17 + 16] + (uint)d + 1;
+
+				}
+
+				/*
+	             * Output cipher state.
+	             */
+				outWords[0] = b0;
+				outWords[1] = b1;
+				outWords[2] = b2;
+				outWords[3] = b3;
+				outWords[4] = b4;
+				outWords[5] = b5;
+				outWords[6] = b6;
+				outWords[7] = b7;
+				outWords[8] = b8;
+				outWords[9] = b9;
+				outWords[10] = b10;
+				outWords[11] = b11;
+				outWords[12] = b12;
+				outWords[13] = b13;
+				outWords[14] = b14;
+				outWords[15] = b15;
+			}
+
+			internal override void DecryptBlock(ulong[] block, ulong[] state)
+			{
+				ulong[] kw = this.kw;
+				ulong[] t = this.t;
+				int[] mod17 = MOD17;
+				int[] mod3 = MOD3;
+
+				/* Help the JIT avoid index bounds checks */
+				if (kw.Length != 33)
+				{
+					throw new ArgumentException();
+				}
+				if (t.Length != 5)
+				{
+					throw new ArgumentException();
+				}
+
+				ulong b0 = block[0];
+				ulong b1 = block[1];
+				ulong b2 = block[2];
+				ulong b3 = block[3];
+				ulong b4 = block[4];
+				ulong b5 = block[5];
+				ulong b6 = block[6];
+				ulong b7 = block[7];
+				ulong b8 = block[8];
+				ulong b9 = block[9];
+				ulong b10 = block[10];
+				ulong b11 = block[11];
+				ulong b12 = block[12];
+				ulong b13 = block[13];
+				ulong b14 = block[14];
+				ulong b15 = block[15];
+
+				for (int d = (ROUNDS_1024 / 4) - 1; d >= 1; d -= 2)
+				{
+					int dm17 = mod17[d];
+					int dm3 = mod3[d];
+
+					/* Reverse key injection for second 4 rounds */
+					b0 -= kw[dm17 + 1];
+					b1 -= kw[dm17 + 2];
+					b2 -= kw[dm17 + 3];
+					b3 -= kw[dm17 + 4];
+					b4 -= kw[dm17 + 5];
+					b5 -= kw[dm17 + 6];
+					b6 -= kw[dm17 + 7];
+					b7 -= kw[dm17 + 8];
+					b8 -= kw[dm17 + 9];
+					b9 -= kw[dm17 + 10];
+					b10 -= kw[dm17 + 11];
+					b11 -= kw[dm17 + 12];
+					b12 -= kw[dm17 + 13];
+					b13 -= kw[dm17 + 14] + t[dm3 + 1];
+					b14 -= kw[dm17 + 15] + t[dm3 + 2];
+					b15 -= kw[dm17 + 16] + (uint)d + 1;
+
+					/* Reverse second 4 mix/permute rounds */
+					b15 = XorRotr(b15, ROTATION_7_0, b0);
+					b0 -= b15;
+					b11 = XorRotr(b11, ROTATION_7_1, b2);
+					b2 -= b11;
+					b13 = XorRotr(b13, ROTATION_7_2, b6);
+					b6 -= b13;
+					b9 = XorRotr(b9, ROTATION_7_3, b4);
+					b4 -= b9;
+					b1 = XorRotr(b1, ROTATION_7_4, b14);
+					b14 -= b1;
+					b5 = XorRotr(b5, ROTATION_7_5, b8);
+					b8 -= b5;
+					b3 = XorRotr(b3, ROTATION_7_6, b10);
+					b10 -= b3;
+					b7 = XorRotr(b7, ROTATION_7_7, b12);
+					b12 -= b7;
+
+					b7 = XorRotr(b7, ROTATION_6_0, b0);
+					b0 -= b7;
+					b5 = XorRotr(b5, ROTATION_6_1, b2);
+					b2 -= b5;
+					b3 = XorRotr(b3, ROTATION_6_2, b4);
+					b4 -= b3;
+					b1 = XorRotr(b1, ROTATION_6_3, b6);
+					b6 -= b1;
+					b15 = XorRotr(b15, ROTATION_6_4, b12);
+					b12 -= b15;
+					b13 = XorRotr(b13, ROTATION_6_5, b14);
+					b14 -= b13;
+					b11 = XorRotr(b11, ROTATION_6_6, b8);
+					b8 -= b11;
+					b9 = XorRotr(b9, ROTATION_6_7, b10);
+					b10 -= b9;
+
+					b9 = XorRotr(b9, ROTATION_5_0, b0);
+					b0 -= b9;
+					b13 = XorRotr(b13, ROTATION_5_1, b2);
+					b2 -= b13;
+					b11 = XorRotr(b11, ROTATION_5_2, b6);
+					b6 -= b11;
+					b15 = XorRotr(b15, ROTATION_5_3, b4);
+					b4 -= b15;
+					b7 = XorRotr(b7, ROTATION_5_4, b10);
+					b10 -= b7;
+					b3 = XorRotr(b3, ROTATION_5_5, b12);
+					b12 -= b3;
+					b5 = XorRotr(b5, ROTATION_5_6, b14);
+					b14 -= b5;
+					b1 = XorRotr(b1, ROTATION_5_7, b8);
+					b8 -= b1;
+
+					b1 = XorRotr(b1, ROTATION_4_0, b0);
+					b0 -= b1;
+					b3 = XorRotr(b3, ROTATION_4_1, b2);
+					b2 -= b3;
+					b5 = XorRotr(b5, ROTATION_4_2, b4);
+					b4 -= b5;
+					b7 = XorRotr(b7, ROTATION_4_3, b6);
+					b6 -= b7;
+					b9 = XorRotr(b9, ROTATION_4_4, b8);
+					b8 -= b9;
+					b11 = XorRotr(b11, ROTATION_4_5, b10);
+					b10 -= b11;
+					b13 = XorRotr(b13, ROTATION_4_6, b12);
+					b12 -= b13;
+					b15 = XorRotr(b15, ROTATION_4_7, b14);
+					b14 -= b15;
+
+					/* Reverse key injection for first 4 rounds */
+					b0 -= kw[dm17];
+					b1 -= kw[dm17 + 1];
+					b2 -= kw[dm17 + 2];
+					b3 -= kw[dm17 + 3];
+					b4 -= kw[dm17 + 4];
+					b5 -= kw[dm17 + 5];
+					b6 -= kw[dm17 + 6];
+					b7 -= kw[dm17 + 7];
+					b8 -= kw[dm17 + 8];
+					b9 -= kw[dm17 + 9];
+					b10 -= kw[dm17 + 10];
+					b11 -= kw[dm17 + 11];
+					b12 -= kw[dm17 + 12];
+					b13 -= kw[dm17 + 13] + t[dm3];
+					b14 -= kw[dm17 + 14] + t[dm3 + 1];
+					b15 -= kw[dm17 + 15] + (uint)d;
+
+					/* Reverse first 4 mix/permute rounds */
+					b15 = XorRotr(b15, ROTATION_3_0, b0);
+					b0 -= b15;
+					b11 = XorRotr(b11, ROTATION_3_1, b2);
+					b2 -= b11;
+					b13 = XorRotr(b13, ROTATION_3_2, b6);
+					b6 -= b13;
+					b9 = XorRotr(b9, ROTATION_3_3, b4);
+					b4 -= b9;
+					b1 = XorRotr(b1, ROTATION_3_4, b14);
+					b14 -= b1;
+					b5 = XorRotr(b5, ROTATION_3_5, b8);
+					b8 -= b5;
+					b3 = XorRotr(b3, ROTATION_3_6, b10);
+					b10 -= b3;
+					b7 = XorRotr(b7, ROTATION_3_7, b12);
+					b12 -= b7;
+
+					b7 = XorRotr(b7, ROTATION_2_0, b0);
+					b0 -= b7;
+					b5 = XorRotr(b5, ROTATION_2_1, b2);
+					b2 -= b5;
+					b3 = XorRotr(b3, ROTATION_2_2, b4);
+					b4 -= b3;
+					b1 = XorRotr(b1, ROTATION_2_3, b6);
+					b6 -= b1;
+					b15 = XorRotr(b15, ROTATION_2_4, b12);
+					b12 -= b15;
+					b13 = XorRotr(b13, ROTATION_2_5, b14);
+					b14 -= b13;
+					b11 = XorRotr(b11, ROTATION_2_6, b8);
+					b8 -= b11;
+					b9 = XorRotr(b9, ROTATION_2_7, b10);
+					b10 -= b9;
+
+					b9 = XorRotr(b9, ROTATION_1_0, b0);
+					b0 -= b9;
+					b13 = XorRotr(b13, ROTATION_1_1, b2);
+					b2 -= b13;
+					b11 = XorRotr(b11, ROTATION_1_2, b6);
+					b6 -= b11;
+					b15 = XorRotr(b15, ROTATION_1_3, b4);
+					b4 -= b15;
+					b7 = XorRotr(b7, ROTATION_1_4, b10);
+					b10 -= b7;
+					b3 = XorRotr(b3, ROTATION_1_5, b12);
+					b12 -= b3;
+					b5 = XorRotr(b5, ROTATION_1_6, b14);
+					b14 -= b5;
+					b1 = XorRotr(b1, ROTATION_1_7, b8);
+					b8 -= b1;
+
+					b1 = XorRotr(b1, ROTATION_0_0, b0);
+					b0 -= b1;
+					b3 = XorRotr(b3, ROTATION_0_1, b2);
+					b2 -= b3;
+					b5 = XorRotr(b5, ROTATION_0_2, b4);
+					b4 -= b5;
+					b7 = XorRotr(b7, ROTATION_0_3, b6);
+					b6 -= b7;
+					b9 = XorRotr(b9, ROTATION_0_4, b8);
+					b8 -= b9;
+					b11 = XorRotr(b11, ROTATION_0_5, b10);
+					b10 -= b11;
+					b13 = XorRotr(b13, ROTATION_0_6, b12);
+					b12 -= b13;
+					b15 = XorRotr(b15, ROTATION_0_7, b14);
+					b14 -= b15;
+				}
+
+				/*
+	             * First subkey uninjection.
+	             */
+				b0 -= kw[0];
+				b1 -= kw[1];
+				b2 -= kw[2];
+				b3 -= kw[3];
+				b4 -= kw[4];
+				b5 -= kw[5];
+				b6 -= kw[6];
+				b7 -= kw[7];
+				b8 -= kw[8];
+				b9 -= kw[9];
+				b10 -= kw[10];
+				b11 -= kw[11];
+				b12 -= kw[12];
+				b13 -= kw[13] + t[0];
+				b14 -= kw[14] + t[1];
+				b15 -= kw[15];
+
+				/*
+	             * Output cipher state.
+	             */
+				state[0] = b0;
+				state[1] = b1;
+				state[2] = b2;
+				state[3] = b3;
+				state[4] = b4;
+				state[5] = b5;
+				state[6] = b6;
+				state[7] = b7;
+				state[8] = b8;
+				state[9] = b9;
+				state[10] = b10;
+				state[11] = b11;
+				state[12] = b12;
+				state[13] = b13;
+				state[14] = b14;
+				state[15] = b15;
+			}
+
+		}
+
+	}
+}
\ No newline at end of file
diff --git a/crypto/src/crypto/parameters/TweakableBlockCipherParameters.cs b/crypto/src/crypto/parameters/TweakableBlockCipherParameters.cs
new file mode 100644
index 000000000..f75726600
--- /dev/null
+++ b/crypto/src/crypto/parameters/TweakableBlockCipherParameters.cs
@@ -0,0 +1,40 @@
+using System;
+using Org.BouncyCastle.Utilities;
+
+namespace Org.BouncyCastle.Crypto.Parameters
+{
+
+	/// <summary>
+	/// Parameters for tweakable block ciphers.
+	/// </summary>
+	public class TweakableBlockCipherParameters
+		: ICipherParameters
+	{
+		private readonly byte[] tweak;
+		private readonly KeyParameter key;
+
+		public TweakableBlockCipherParameters(KeyParameter key, byte[] tweak)
+		{
+			this.key = key;
+			this.tweak = Arrays.Clone(tweak);
+		}
+
+		/// <summary>
+		/// Gets the key.
+		/// </summary>
+		/// <value>the key to use, or <code>null</code> to use the current key.</value>
+		public KeyParameter Key
+		{
+			get { return key; }
+		}
+
+		/// <summary>
+		/// Gets the tweak value.
+		/// </summary>
+		/// <value>The tweak to use, or <code>null</code> to use the current tweak.</value>
+		public byte[] Tweak
+		{
+			get { return tweak; }
+		}
+	}
+}
\ No newline at end of file
diff --git a/crypto/test/src/crypto/test/CipherTest.cs b/crypto/test/src/crypto/test/CipherTest.cs
index a893e0239..d9c085d44 100644
--- a/crypto/test/src/crypto/test/CipherTest.cs
+++ b/crypto/test/src/crypto/test/CipherTest.cs
@@ -42,7 +42,7 @@ namespace Org.BouncyCastle.Crypto.Tests
 				//
 				// state tests
 				//
-				byte[] buf = new byte[16];
+				byte[] buf = new byte[_engine.GetBlockSize()];
 
 				try
 				{
diff --git a/crypto/test/src/crypto/test/RegressionTest.cs b/crypto/test/src/crypto/test/RegressionTest.cs
index 687e9ee4f..0f08d47f4 100644
--- a/crypto/test/src/crypto/test/RegressionTest.cs
+++ b/crypto/test/src/crypto/test/RegressionTest.cs
@@ -39,6 +39,9 @@ namespace Org.BouncyCastle.Crypto.Tests
             new SkipjackTest(),
             new BlowfishTest(),
             new TwofishTest(),
+            new Threefish256Test(),
+            new Threefish512Test(),
+            new Threefish1024Test(),
             new Cast5Test(),
             new Cast6Test(),
             new Gost28147Test(),
diff --git a/crypto/test/src/crypto/test/Threefish1024Test.cs b/crypto/test/src/crypto/test/Threefish1024Test.cs
new file mode 100644
index 000000000..64f9aa29f
--- /dev/null
+++ b/crypto/test/src/crypto/test/Threefish1024Test.cs
@@ -0,0 +1,74 @@
+using System;
+
+using NUnit.Framework;
+
+using Org.BouncyCastle.Crypto.Engines;
+using Org.BouncyCastle.Crypto.Parameters;
+using Org.BouncyCastle.Utilities.Encoders;
+using Org.BouncyCastle.Utilities.Test;
+
+namespace Org.BouncyCastle.Crypto.Tests
+{
+
+	[TestFixture]
+	public class Threefish1024Test
+		: CipherTest
+	{
+		// Test cases from skein_golden_kat_internals.txt in Skein 1.3 NIST CD
+		static SimpleTest[] tests =
+		{
+			new BlockCipherVectorTest(0, new ThreefishEngine(ThreefishEngine.BLOCKSIZE_1024),
+			                          new TweakableBlockCipherParameters(
+				new KeyParameter(new byte[128]),
+				new byte[16]),
+			                          "0000000000000000000000000000000000000000000000000000000000000000" +
+			                          "0000000000000000000000000000000000000000000000000000000000000000" +
+			                          "0000000000000000000000000000000000000000000000000000000000000000" +
+			                          "0000000000000000000000000000000000000000000000000000000000000000",
+			                          "f05c3d0a3d05b304f785ddc7d1e036015c8aa76e2f217b06c6e1544c0bc1a90d" +
+			                          "f0accb9473c24e0fd54fea68057f43329cb454761d6df5cf7b2e9b3614fbd5a2" +
+			                          "0b2e4760b40603540d82eabc5482c171c832afbe68406bc39500367a592943fa" +
+			                          "9a5b4a43286ca3c4cf46104b443143d560a4b230488311df4feef7e1dfe8391e"),
+			new BlockCipherVectorTest(1, new ThreefishEngine(ThreefishEngine.BLOCKSIZE_1024),
+			                          new TweakableBlockCipherParameters(
+				new KeyParameter(Hex.Decode(
+				"101112131415161718191a1b1c1d1e1f202122232425262728292a2b2c2d2e2f" +
+				"303132333435363738393a3b3c3d3e3f404142434445464748494a4b4c4d4e4f" +
+				"505152535455565758595a5b5c5d5e5f606162636465666768696a6b6c6d6e6f" +
+				"707172737475767778797a7b7c7d7e7f808182838485868788898a8b8c8d8e8f")),
+				Hex.Decode("000102030405060708090a0b0c0d0e0f")),
+			                          "fffefdfcfbfaf9f8f7f6f5f4f3f2f1f0efeeedecebeae9e8e7e6e5e4e3e2e1e0" +
+			                          "dfdedddcdbdad9d8d7d6d5d4d3d2d1d0cfcecdcccbcac9c8c7c6c5c4c3c2c1c0" +
+			                          "bfbebdbcbbbab9b8b7b6b5b4b3b2b1b0afaeadacabaaa9a8a7a6a5a4a3a2a1a0" +
+			                          "9f9e9d9c9b9a999897969594939291908f8e8d8c8b8a89888786858483828180",
+			                          "a6654ddbd73cc3b05dd777105aa849bce49372eaaffc5568d254771bab85531c" +
+			                          "94f780e7ffaae430d5d8af8c70eebbe1760f3b42b737a89cb363490d670314bd" +
+			                          "8aa41ee63c2e1f45fbd477922f8360b388d6125ea6c7af0ad7056d01796e90c8" +
+			                          "3313f4150a5716b30ed5f569288ae974ce2b4347926fce57de44512177dd7cde")
+		};
+
+		public Threefish1024Test()
+			: base(tests, new ThreefishEngine(ThreefishEngine.BLOCKSIZE_1024), new KeyParameter(new byte[128]))
+		{
+		}
+
+		public override string Name
+		{
+			get { return "Threefish-1024"; }
+		}
+
+		public static void Main(
+			string[] args)
+		{
+			RunTest(new Threefish1024Test());
+		}
+
+		[Test]
+		public void TestFunction()
+		{
+			string resultText = Perform().ToString();
+
+			Assert.AreEqual(Name + ": Okay", resultText);
+		}
+	}
+}
diff --git a/crypto/test/src/crypto/test/Threefish256Test.cs b/crypto/test/src/crypto/test/Threefish256Test.cs
new file mode 100644
index 000000000..e44299a31
--- /dev/null
+++ b/crypto/test/src/crypto/test/Threefish256Test.cs
@@ -0,0 +1,59 @@
+using System;
+
+using NUnit.Framework;
+
+using Org.BouncyCastle.Crypto.Engines;
+using Org.BouncyCastle.Crypto.Parameters;
+using Org.BouncyCastle.Utilities.Encoders;
+using Org.BouncyCastle.Utilities.Test;
+
+namespace Org.BouncyCastle.Crypto.Tests
+{
+
+	[TestFixture]
+	public class Threefish256Test
+		: CipherTest
+	{
+		// Test cases from skein_golden_kat_internals.txt in Skein 1.3 NIST CD
+		static SimpleTest[] tests =
+		{
+			new BlockCipherVectorTest(0, new ThreefishEngine(ThreefishEngine.BLOCKSIZE_256),
+			                          new TweakableBlockCipherParameters(
+				new KeyParameter(new byte[32]),
+				new byte[16]),
+			                          "0000000000000000000000000000000000000000000000000000000000000000",
+			                          "84da2a1f8beaee947066ae3e3103f1ad536db1f4a1192495116b9f3ce6133fd8"),
+			new BlockCipherVectorTest(1, new ThreefishEngine(ThreefishEngine.BLOCKSIZE_256),
+			                          new TweakableBlockCipherParameters(
+				new KeyParameter(Hex.Decode(
+				"101112131415161718191a1b1c1d1e1f202122232425262728292a2b2c2d2e2f")),
+				Hex.Decode("000102030405060708090a0b0c0d0e0f")),
+			                          "FFFEFDFCFBFAF9F8F7F6F5F4F3F2F1F0EFEEEDECEBEAE9E8E7E6E5E4E3E2E1E0",
+			                          "e0d091ff0eea8fdfc98192e62ed80ad59d865d08588df476657056b5955e97df")
+		};
+
+		public Threefish256Test()
+			: base(tests, new ThreefishEngine(ThreefishEngine.BLOCKSIZE_256), new KeyParameter(new byte[32]))
+		{
+		}
+
+		public override string Name
+		{
+			get { return "Threefish-256"; }
+		}
+
+		public static void Main(
+			string[] args)
+		{
+			RunTest(new Threefish256Test());
+		}
+
+		[Test]
+		public void TestFunction()
+		{
+			string resultText = Perform().ToString();
+
+			Assert.AreEqual(Name + ": Okay", resultText);
+		}
+	}
+}
\ No newline at end of file
diff --git a/crypto/test/src/crypto/test/Threefish512Test.cs b/crypto/test/src/crypto/test/Threefish512Test.cs
new file mode 100644
index 000000000..8f4ec6345
--- /dev/null
+++ b/crypto/test/src/crypto/test/Threefish512Test.cs
@@ -0,0 +1,64 @@
+using System;
+
+using NUnit.Framework;
+
+using Org.BouncyCastle.Crypto.Engines;
+using Org.BouncyCastle.Crypto.Parameters;
+using Org.BouncyCastle.Utilities.Encoders;
+using Org.BouncyCastle.Utilities.Test;
+
+namespace Org.BouncyCastle.Crypto.Tests
+{
+
+	[TestFixture]
+	public class Threefish512Test
+		: CipherTest
+	{
+		// Test cases from skein_golden_kat_internals.txt in Skein 1.3 NIST CD
+		static SimpleTest[] tests =
+		{
+			new BlockCipherVectorTest(0, new ThreefishEngine(ThreefishEngine.BLOCKSIZE_512),
+			                          new TweakableBlockCipherParameters(
+				new KeyParameter(new byte[64]),
+				new byte[16]),
+			                          "0000000000000000000000000000000000000000000000000000000000000000" +
+			                          "0000000000000000000000000000000000000000000000000000000000000000",
+			                          "b1a2bbc6ef6025bc40eb3822161f36e375d1bb0aee3186fbd19e47c5d479947b" +
+			                          "7bc2f8586e35f0cff7e7f03084b0b7b1f1ab3961a580a3e97eb41ea14a6d7bbe"),
+			new BlockCipherVectorTest(1, new ThreefishEngine(ThreefishEngine.BLOCKSIZE_512),
+			                          new TweakableBlockCipherParameters(
+				new KeyParameter(Hex.Decode(
+				"101112131415161718191a1b1c1d1e1f202122232425262728292a2b2c2d2e2f" +
+				"303132333435363738393a3b3c3d3e3f404142434445464748494a4b4c4d4e4f")),
+				Hex.Decode("000102030405060708090a0b0c0d0e0f")),
+			                          "fffefdfcfbfaf9f8f7f6f5f4f3f2f1f0efeeedecebeae9e8e7e6e5e4e3e2e1e0" +
+			                          "dfdedddcdbdad9d8d7d6d5d4d3d2d1d0cfcecdcccbcac9c8c7c6c5c4c3c2c1c0",
+			                          "e304439626d45a2cb401cad8d636249a6338330eb06d45dd8b36b90e97254779" +
+			                          "272a0a8d99463504784420ea18c9a725af11dffea10162348927673d5c1caf3d")
+		};
+
+		public Threefish512Test()
+			: base(tests, new ThreefishEngine(ThreefishEngine.BLOCKSIZE_512), new KeyParameter(new byte[64]))
+		{
+		}
+
+		public override string Name
+		{
+			get { return "Threefish-512"; }
+		}
+
+		public static void Main(
+			string[] args)
+		{
+			RunTest(new Threefish512Test());
+		}
+
+		[Test]
+		public void TestFunction()
+		{
+			string resultText = Perform().ToString();
+
+			Assert.AreEqual(Name + ": Okay", resultText);
+		}
+	}
+}
\ No newline at end of file