mirror of
https://github.com/wismna/ModernKeePassLib.git
synced 2025-10-03 15:40:20 -04:00
336 lines
8.6 KiB
C#
336 lines
8.6 KiB
C#
/*
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KeePass Password Safe - The Open-Source Password Manager
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Copyright (C) 2003-2020 Dominik Reichl <dominik.reichl@t-online.de>
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This program is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 2 of the License, or
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(at your option) any later version.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program; if not, write to the Free Software
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Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
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*/
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using System;
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using System.Collections.Generic;
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using System.Diagnostics;
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using System.IO;
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using System.Text;
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#if ModernKeePassLib
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using ModernKeePassLib.Cryptography.Hash;
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#elif !KeePassUAP
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using System.Security.Cryptography;
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#endif
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using ModernKeePassLib.Resources;
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using ModernKeePassLib.Utility;
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namespace ModernKeePassLib.Serialization
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{
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public sealed class HmacBlockStream : Stream
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{
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private const int NbDefaultBufferSize = 1024 * 1024; // 1 MB
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private Stream m_sBase;
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private readonly bool m_bWriting;
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private readonly bool m_bVerify;
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private readonly byte[] m_pbKey;
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private bool m_bEos = false;
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private byte[] m_pbBuffer;
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private int m_iBufferPos = 0;
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private ulong m_uBlockIndex = 0;
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public override bool CanRead
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{
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get { return !m_bWriting; }
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}
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public override bool CanSeek
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{
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get { return false; }
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}
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public override bool CanWrite
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{
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get { return m_bWriting; }
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}
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public override long Length
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{
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get { Debug.Assert(false); throw new NotSupportedException(); }
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}
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public override long Position
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{
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get { Debug.Assert(false); throw new NotSupportedException(); }
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set { Debug.Assert(false); throw new NotSupportedException(); }
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}
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public HmacBlockStream(Stream sBase, bool bWriting, bool bVerify,
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byte[] pbKey)
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{
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if(sBase == null) throw new ArgumentNullException("sBase");
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if(pbKey == null) throw new ArgumentNullException("pbKey");
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m_sBase = sBase;
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m_bWriting = bWriting;
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m_bVerify = bVerify;
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m_pbKey = pbKey;
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if(!m_bWriting) // Reading mode
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{
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if(!m_sBase.CanRead) throw new InvalidOperationException();
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m_pbBuffer = MemUtil.EmptyByteArray;
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}
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else // Writing mode
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{
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if(!m_sBase.CanWrite) throw new InvalidOperationException();
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m_pbBuffer = new byte[NbDefaultBufferSize];
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}
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}
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protected override void Dispose(bool disposing)
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{
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if(disposing && (m_sBase != null))
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{
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if(m_bWriting)
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{
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if(m_iBufferPos == 0) // No data left in buffer
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WriteSafeBlock(); // Write terminating block
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else
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{
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WriteSafeBlock(); // Write remaining buffered data
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WriteSafeBlock(); // Write terminating block
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}
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Flush();
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}
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m_sBase.Dispose();
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m_sBase = null;
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}
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SetBuffer(MemUtil.EmptyByteArray);
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base.Dispose(disposing);
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}
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private void SetBuffer(byte[] pb)
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{
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MemUtil.ZeroByteArray(m_pbBuffer); // Erase previous buffer
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m_pbBuffer = pb;
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}
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public override void Flush()
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{
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Debug.Assert(m_sBase != null); // Object should not be disposed
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if(m_bWriting && (m_sBase != null)) m_sBase.Flush();
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}
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public override long Seek(long lOffset, SeekOrigin soOrigin)
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{
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Debug.Assert(false);
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throw new NotSupportedException();
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}
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public override void SetLength(long lValue)
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{
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Debug.Assert(false);
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throw new NotSupportedException();
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}
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internal static byte[] GetHmacKey64(byte[] pbKey, ulong uBlockIndex)
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{
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if(pbKey == null) throw new ArgumentNullException("pbKey");
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Debug.Assert(pbKey.Length == 64);
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// We are computing the HMAC using SHA-256, whose internal
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// block size is 512 bits; thus create a key that is 512
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// bits long (using SHA-512)
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byte[] pbBlockKey;
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using(SHA512Managed h = new SHA512Managed())
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{
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byte[] pbIndex = MemUtil.UInt64ToBytes(uBlockIndex);
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h.TransformBlock(pbIndex, 0, pbIndex.Length, pbIndex, 0);
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h.TransformBlock(pbKey, 0, pbKey.Length, pbKey, 0);
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h.TransformFinalBlock(MemUtil.EmptyByteArray, 0, 0);
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pbBlockKey = h.Hash;
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}
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#if DEBUG
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byte[] pbZero = new byte[64];
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Debug.Assert((pbBlockKey.Length == 64) && !MemUtil.ArraysEqual(
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pbBlockKey, pbZero)); // Ensure we own pbBlockKey
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#endif
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return pbBlockKey;
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}
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public override int Read(byte[] pbBuffer, int iOffset, int nCount)
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{
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if(m_bWriting) throw new InvalidOperationException();
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int nRemaining = nCount;
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while(nRemaining > 0)
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{
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if(m_iBufferPos == m_pbBuffer.Length)
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{
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if(!ReadSafeBlock())
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return (nCount - nRemaining); // Bytes actually read
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}
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int nCopy = Math.Min(m_pbBuffer.Length - m_iBufferPos, nRemaining);
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Debug.Assert(nCopy > 0);
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Array.Copy(m_pbBuffer, m_iBufferPos, pbBuffer, iOffset, nCopy);
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iOffset += nCopy;
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m_iBufferPos += nCopy;
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nRemaining -= nCopy;
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}
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return nCount;
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}
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private bool ReadSafeBlock()
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{
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if(m_bEos) return false; // End of stream reached already
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byte[] pbStoredHmac = MemUtil.Read(m_sBase, 32);
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if((pbStoredHmac == null) || (pbStoredHmac.Length != 32))
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throw new EndOfStreamException(KLRes.FileCorrupted + " " +
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KLRes.FileIncomplete);
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// Block index is implicit: it's used in the HMAC computation,
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// but does not need to be stored
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// byte[] pbBlockIndex = MemUtil.Read(m_sBase, 8);
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// if((pbBlockIndex == null) || (pbBlockIndex.Length != 8))
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// throw new EndOfStreamException();
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// ulong uBlockIndex = MemUtil.BytesToUInt64(pbBlockIndex);
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// if((uBlockIndex != m_uBlockIndex) && m_bVerify)
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// throw new InvalidDataException();
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byte[] pbBlockIndex = MemUtil.UInt64ToBytes(m_uBlockIndex);
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byte[] pbBlockSize = MemUtil.Read(m_sBase, 4);
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if((pbBlockSize == null) || (pbBlockSize.Length != 4))
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throw new EndOfStreamException(KLRes.FileCorrupted + " " +
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KLRes.FileIncomplete);
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int nBlockSize = MemUtil.BytesToInt32(pbBlockSize);
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if(nBlockSize < 0)
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throw new InvalidDataException(KLRes.FileCorrupted);
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m_iBufferPos = 0;
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SetBuffer(MemUtil.Read(m_sBase, nBlockSize));
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if((m_pbBuffer == null) || ((m_pbBuffer.Length != nBlockSize) && m_bVerify))
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throw new EndOfStreamException(KLRes.FileCorrupted + " " +
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KLRes.FileIncompleteExpc);
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if(m_bVerify)
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{
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byte[] pbCmpHmac;
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byte[] pbBlockKey = GetHmacKey64(m_pbKey, m_uBlockIndex);
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using(HMACSHA256 h = new HMACSHA256(pbBlockKey))
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{
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h.TransformBlock(pbBlockIndex, 0, pbBlockIndex.Length,
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pbBlockIndex, 0);
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h.TransformBlock(pbBlockSize, 0, pbBlockSize.Length,
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pbBlockSize, 0);
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if(m_pbBuffer.Length != 0)
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h.TransformBlock(m_pbBuffer, 0, m_pbBuffer.Length,
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m_pbBuffer, 0);
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h.TransformFinalBlock(MemUtil.EmptyByteArray, 0, 0);
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pbCmpHmac = h.Hash;
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}
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MemUtil.ZeroByteArray(pbBlockKey);
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if(!MemUtil.ArraysEqual(pbCmpHmac, pbStoredHmac))
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throw new InvalidDataException(KLRes.FileCorrupted);
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}
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++m_uBlockIndex;
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if(nBlockSize == 0)
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{
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m_bEos = true;
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return false; // No further data available
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}
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return true;
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}
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public override void Write(byte[] pbBuffer, int iOffset, int nCount)
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{
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if(!m_bWriting) throw new InvalidOperationException();
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while(nCount > 0)
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{
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if(m_iBufferPos == m_pbBuffer.Length)
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WriteSafeBlock();
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int nCopy = Math.Min(m_pbBuffer.Length - m_iBufferPos, nCount);
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Debug.Assert(nCopy > 0);
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Array.Copy(pbBuffer, iOffset, m_pbBuffer, m_iBufferPos, nCopy);
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iOffset += nCopy;
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m_iBufferPos += nCopy;
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nCount -= nCopy;
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}
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}
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private void WriteSafeBlock()
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{
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byte[] pbBlockIndex = MemUtil.UInt64ToBytes(m_uBlockIndex);
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int cbBlockSize = m_iBufferPos;
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byte[] pbBlockSize = MemUtil.Int32ToBytes(cbBlockSize);
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byte[] pbBlockHmac;
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byte[] pbBlockKey = GetHmacKey64(m_pbKey, m_uBlockIndex);
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using(HMACSHA256 h = new HMACSHA256(pbBlockKey))
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{
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h.TransformBlock(pbBlockIndex, 0, pbBlockIndex.Length,
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pbBlockIndex, 0);
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h.TransformBlock(pbBlockSize, 0, pbBlockSize.Length,
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pbBlockSize, 0);
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if(cbBlockSize != 0)
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h.TransformBlock(m_pbBuffer, 0, cbBlockSize, m_pbBuffer, 0);
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h.TransformFinalBlock(MemUtil.EmptyByteArray, 0, 0);
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pbBlockHmac = h.Hash;
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}
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MemUtil.ZeroByteArray(pbBlockKey);
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MemUtil.Write(m_sBase, pbBlockHmac);
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// MemUtil.Write(m_sBase, pbBlockIndex); // Implicit
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MemUtil.Write(m_sBase, pbBlockSize);
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if(cbBlockSize != 0)
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m_sBase.Write(m_pbBuffer, 0, cbBlockSize);
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++m_uBlockIndex;
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m_iBufferPos = 0;
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}
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}
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}
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