1 files changed, 168 insertions, 0 deletions
diff --git a/crypto/src/crypto/engines/XTEAEngine.cs b/crypto/src/crypto/engines/XTEAEngine.cs
new file mode 100644
index 000000000..eb9291775
--- /dev/null
+++ b/crypto/src/crypto/engines/XTEAEngine.cs
@@ -0,0 +1,168 @@
+using System;
+
+using Org.BouncyCastle.Crypto.Parameters;
+using Org.BouncyCastle.Crypto.Utilities;
+
+namespace Org.BouncyCastle.Crypto.Engines
+{
+	/**
+	* An XTEA engine.
+	*/
+	public class XteaEngine
+		: IBlockCipher
+	{
+		private const int
+			rounds		= 32,
+			block_size	= 8,
+//			key_size	= 16,
+			delta		= unchecked((int) 0x9E3779B9);
+
+		/*
+		* the expanded key array of 4 subkeys
+		*/
+		private uint[] _S = new uint[4],
+			_sum0 = new uint[32],
+			_sum1 = new uint[32];
+		private bool _initialised, _forEncryption;
+
+		/**
+		* Create an instance of the TEA encryption algorithm
+		* and set some defaults
+		*/
+		public XteaEngine()
+		{
+			_initialised = false;
+		}
+
+		public string AlgorithmName
+		{
+			get { return "XTEA"; }
+		}
+
+		public bool IsPartialBlockOkay
+		{
+			get { return false; }
+		}
+
+		public int GetBlockSize()
+		{
+			return block_size;
+		}
+
+		/**
+		* initialise
+		*
+		* @param forEncryption whether or not we are for encryption.
+		* @param params the parameters required to set up the cipher.
+		* @exception ArgumentException if the params argument is
+		* inappropriate.
+		*/
+		public void Init(
+			bool				forEncryption,
+			ICipherParameters	parameters)
+		{
+			if (!(parameters is KeyParameter))
+			{
+				throw new ArgumentException("invalid parameter passed to TEA init - "
+					+ parameters.GetType().FullName);
+			}
+
+			_forEncryption = forEncryption;
+			_initialised = true;
+
+			KeyParameter p = (KeyParameter) parameters;
+
+			setKey(p.GetKey());
+		}
+
+		public int ProcessBlock(
+			byte[]	inBytes,
+			int		inOff,
+			byte[]	outBytes,
+			int		outOff)
+		{
+			if (!_initialised)
+				throw new InvalidOperationException(AlgorithmName + " not initialised");
+
+			if ((inOff + block_size) > inBytes.Length)
+				throw new DataLengthException("input buffer too short");
+
+			if ((outOff + block_size) > outBytes.Length)
+				throw new DataLengthException("output buffer too short");
+
+			return _forEncryption
+				?	encryptBlock(inBytes, inOff, outBytes, outOff)
+				:	decryptBlock(inBytes, inOff, outBytes, outOff);
+		}
+
+		public void Reset()
+		{
+		}
+
+		/**
+		* Re-key the cipher.
+		*
+		* @param  key  the key to be used
+		*/
+		private void setKey(
+			byte[] key)
+		{
+			int i, j;
+			for (i = j = 0; i < 4; i++,j+=4)
+			{
+				_S[i] = Pack.BE_To_UInt32(key, j);
+			}
+
+			for (i = j = 0; i < rounds; i++)
+			{
+				_sum0[i] = ((uint)j + _S[j & 3]);
+				j += delta;
+				_sum1[i] = ((uint)j + _S[j >> 11 & 3]);
+			}
+		}
+
+		private int encryptBlock(
+			byte[]  inBytes,
+			int     inOff,
+			byte[]  outBytes,
+			int     outOff)
+		{
+			// Pack bytes into integers
+			uint v0 = Pack.BE_To_UInt32(inBytes, inOff);
+			uint v1 = Pack.BE_To_UInt32(inBytes, inOff + 4);
+
+			for (int i = 0; i < rounds; i++)
+			{
+				v0 += ((v1 << 4 ^ v1 >> 5) + v1) ^ _sum0[i];
+				v1 += ((v0 << 4 ^ v0 >> 5) + v0) ^ _sum1[i];
+			}
+
+			Pack.UInt32_To_BE(v0, outBytes, outOff);
+			Pack.UInt32_To_BE(v1, outBytes, outOff + 4);
+
+			return block_size;
+		}
+
+		private int decryptBlock(
+			byte[]	inBytes,
+			int		inOff,
+			byte[]	outBytes,
+			int		outOff)
+		{
+			// Pack bytes into integers
+			uint v0 = Pack.BE_To_UInt32(inBytes, inOff);
+			uint v1 = Pack.BE_To_UInt32(inBytes, inOff + 4);
+
+			for (int i = rounds-1; i >= 0; i--)
+			{
+				v1  -= ((v0 << 4 ^ v0 >> 5) + v0) ^ _sum1[i];
+				v0  -= ((v1 << 4 ^ v1 >> 5) + v1) ^ _sum0[i];
+			}
+
+			Pack.UInt32_To_BE(v0, outBytes, outOff);
+			Pack.UInt32_To_BE(v1, outBytes, outOff + 4);
+
+			return block_size;
+		}
+	}
+}