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Password Safe Database Reader Library in C# for .NET

, 16 Oct 2007 GPL3
An independent library implementation to read Password Safe Password Manager V3 database files
using System;
using System.Diagnostics;
using System.Security.Cryptography;

namespace ManyMonkeys.Cryptography
{
	/// <summary>
	/// Summary description for TwofishEncryption.
	/// </summary>
	internal class TwofishEncryption : TwofishBase, ICryptoTransform
	{
		public TwofishEncryption(int keyLen, ref byte[] key, ref byte[] iv, CipherMode cMode, EncryptionDirection direction)
		{
			// convert our key into an array of ints
			for (int i=0;i<key.Length/4;i++)
			{
				Key[i] = (uint)( key[i*4+3]<<24) | (uint)(key[i*4+2] << 16) | (uint)(key[i*4+1] << 8) | (uint)(key[i*4+0]);
			}

			cipherMode = cMode;

			// we only need to convert our IV if we are using CBC
			if (cipherMode == CipherMode.CBC)
			{
				for (int i=0;i<4;i++)
				{
					IV[i] = (uint)( iv[i*4+3]<<24) | (uint)(iv[i*4+2] << 16) | (uint)(iv[i*4+1] << 8) | (uint)(iv[i*4+0]);
				}
			}

			encryptionDirection = direction;
			reKey(keyLen,ref Key);
		}

		// need to have this method due to IDisposable - just can't think of a reason to use it for in this class
		public void Dispose()
		{
		}


		/// <summary>
		/// Transform a block depending on whether we are encrypting or decrypting
		/// </summary>
		/// <param name="inputBuffer"></param>
		/// <param name="inputOffset"></param>
		/// <param name="inputCount"></param>
		/// <param name="outputBuffer"></param>
		/// <param name="outputOffset"></param>
		/// <returns></returns>
		public int TransformBlock(
			byte[] inputBuffer,
			int inputOffset,
			int inputCount,
			byte[] outputBuffer,
			int outputOffset
			)
		{			
			uint[] x=new uint[4];

			// load it up
			for (int i=0;i<4;i++)
			{
				x[i]= (uint)(inputBuffer[i*4+3+inputOffset]<<24) | (uint)(inputBuffer[i*4+2+inputOffset] << 16) | 
					(uint)(inputBuffer[i*4+1+inputOffset] << 8) | (uint)(inputBuffer[i*4+0+inputOffset]);

			}

			if (encryptionDirection == EncryptionDirection.Encrypting)
			{
				blockEncrypt(ref x);
			}
			else
			{
				blockDecrypt(ref x);
			}


			// load it up
			for (int i=0;i<4;i++)
			{
				outputBuffer[i*4+0+outputOffset] = b0(x[i]);
				outputBuffer[i*4+1+outputOffset] = b1(x[i]);
				outputBuffer[i*4+2+outputOffset] = b2(x[i]);
				outputBuffer[i*4+3+outputOffset] = b3(x[i]);
			}


			return inputCount;
		}

		public byte[] TransformFinalBlock(
			byte[] inputBuffer,
			int inputOffset,
			int inputCount
			)
		{
			byte[] outputBuffer;// = new byte[0];
			
			if (inputCount>0)
			{
				outputBuffer = new byte[16]; // blocksize
				uint[] x=new uint[4];

				// load it up
				for (int i=0;i<4;i++) // should be okay as we have already said to pad with zeros
				{
					x[i]= (uint)(inputBuffer[i*4+3+inputOffset]<<24) | (uint)(inputBuffer[i*4+2+inputOffset] << 16) | 
						(uint)(inputBuffer[i*4+1+inputOffset] << 8) | (uint)(inputBuffer[i*4+0+inputOffset]);

				}

				if (encryptionDirection == EncryptionDirection.Encrypting)
				{
					blockEncrypt(ref x);
				}
				else
				{
					blockDecrypt(ref x);
				}

				// load it up
				for (int i=0;i<4;i++)
				{
					outputBuffer[i*4+0] = b0(x[i]);
					outputBuffer[i*4+1] = b1(x[i]);
					outputBuffer[i*4+2] = b2(x[i]);
					outputBuffer[i*4+3] = b3(x[i]);
				}
			}
			else
			{
				outputBuffer = new byte[0]; // the .NET framework doesn't like it if you return null - this calms it down
			}
			
			return outputBuffer;
		}

		// not worked out this property yet - placing break points here just don't get caught.
		private bool canReuseTransform = true;
		public bool CanReuseTransform
		{
			get
			{
				return canReuseTransform;
			}
		}

		// I normally set this to false when block encrypting so that I can work on one block at a time
		// but for compression and stream type ciphers this can be set to true so that you get all the data
		private bool canTransformMultipleBlocks = false;
		public bool CanTransformMultipleBlocks
		{
			get
			{
				return canTransformMultipleBlocks;
			}
		}

		public int InputBlockSize
		{
			get
			{
				return inputBlockSize;
			}
		}

		public int OutputBlockSize
		{
			get
			{
				return outputBlockSize;
			}
		}

		private EncryptionDirection encryptionDirection;
	}
}

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License

This article, along with any associated source code and files, is licensed under The GNU General Public License (GPLv3)

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About the Author

Svante Seleborg
Web Developer Axantum Software AB
Sweden Sweden
I've been working with all aspects of software development since 1979 - from compiler construction to management. Currently I'm an independent consultant mostly specializing in computer security. Please see my homepage for contact details.
 
I speak C like a native, and have a pretty good grasp of C++. The most recent five years C# has been the main development language. Traditionally Unix has been the dominating environment, but currently the scales have tipped over to Windows, due to market demands but I'm equally at home developing in both environments.
 
When I'm not coding I'm usually sitting on one of my 4 bikes, indoors or outdoors, on the road or in the woods.

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