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/*
KeePass Password Safe - The Open-Source Password Manager
Copyright (C) 2003-2012 Dominik Reichl <dominik.reichl@t-online.de>
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2 of the License, or
(at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
*/
using System;
using System.Collections.Generic;
using System.Text;
using System.IO;
using System.Security.Cryptography;
using System.Diagnostics;
using KeePassLib.Utility;
namespace KeePassLib.Cryptography
{
public sealed class HashingStreamEx : Stream
{
private Stream m_sBaseStream;
private bool m_bWriting;
private HashAlgorithm m_hash;
private byte[] m_pbFinalHash = null;
public byte[] Hash
{
get { return m_pbFinalHash; }
}
public override bool CanRead
{
get { return !m_bWriting; }
}
public override bool CanSeek
{
get { return false; }
}
public override bool CanWrite
{
get { return m_bWriting; }
}
public override long Length
{
get { return m_sBaseStream.Length; }
}
public override long Position
{
get { return m_sBaseStream.Position; }
set { throw new NotSupportedException(); }
}
public HashingStreamEx(Stream sBaseStream, bool bWriting, HashAlgorithm hashAlgorithm)
{
if(sBaseStream == null) throw new ArgumentNullException("sBaseStream");
m_sBaseStream = sBaseStream;
m_bWriting = bWriting;
#if !KeePassLibSD
m_hash = (hashAlgorithm ?? new SHA256Managed());
#else // KeePassLibSD
m_hash = null;
try { m_hash = HashAlgorithm.Create("SHA256"); }
catch(Exception) { }
try { if(m_hash == null) m_hash = HashAlgorithm.Create(); }
catch(Exception) { }
#endif
if(m_hash == null) { Debug.Assert(false); return; }
// Validate hash algorithm
if((!m_hash.CanReuseTransform) || (!m_hash.CanTransformMultipleBlocks) ||
(m_hash.InputBlockSize != 1) || (m_hash.OutputBlockSize != 1))
{
#if DEBUG
MessageService.ShowWarning("Broken HashAlgorithm object in HashingStreamEx.");
#endif
m_hash = null;
}
}
public override void Flush()
{
m_sBaseStream.Flush();
}
public override void Close()
{
if(m_hash != null)
{
try
{
m_hash.TransformFinalBlock(new byte[0], 0, 0);
m_pbFinalHash = m_hash.Hash;
}
catch(Exception) { Debug.Assert(false); }
m_hash = null;
}
m_sBaseStream.Close();
}
public override long Seek(long lOffset, SeekOrigin soOrigin)
{
throw new NotSupportedException();
}
public override void SetLength(long lValue)
{
throw new NotSupportedException();
}
public override int Read(byte[] pbBuffer, int nOffset, int nCount)
{
if(m_bWriting) throw new InvalidOperationException();
int nRead = m_sBaseStream.Read(pbBuffer, nOffset, nCount);
// Mono bug workaround (LaunchPad 798910)
int nPartialRead = nRead;
while((nRead < nCount) && (nPartialRead != 0))
{
nPartialRead = m_sBaseStream.Read(pbBuffer, nOffset + nRead,
nCount - nRead);
nRead += nPartialRead;
}
#if DEBUG
byte[] pbOrg = new byte[pbBuffer.Length];
Array.Copy(pbBuffer, pbOrg, pbBuffer.Length);
#endif
if((m_hash != null) && (nRead > 0))
m_hash.TransformBlock(pbBuffer, nOffset, nRead, pbBuffer, nOffset);
#if DEBUG
Debug.Assert(MemUtil.ArraysEqual(pbBuffer, pbOrg));
#endif
return nRead;
}
public override void Write(byte[] pbBuffer, int nOffset, int nCount)
{
if(!m_bWriting) throw new InvalidOperationException();
#if DEBUG
byte[] pbOrg = new byte[pbBuffer.Length];
Array.Copy(pbBuffer, pbOrg, pbBuffer.Length);
#endif
if((m_hash != null) && (nCount > 0))
m_hash.TransformBlock(pbBuffer, nOffset, nCount, pbBuffer, nOffset);
#if DEBUG
Debug.Assert(MemUtil.ArraysEqual(pbBuffer, pbOrg));
#endif
m_sBaseStream.Write(pbBuffer, nOffset, nCount);
}
}
}
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