105 lines
2.5 KiB
C#
105 lines
2.5 KiB
C#
/*
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KeePass Password Safe - The Open-Source Password Manager
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Copyright (C) 2003-2017 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.Text;
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using KeePassLib.Utility;
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namespace KeePassLib.Cryptography.Cipher
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{
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public abstract class CtrBlockCipher : IDisposable
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{
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private byte[] m_pBlock;
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private int m_iBlockPos;
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public abstract int BlockSize
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{
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get;
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}
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public CtrBlockCipher()
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{
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int cb = this.BlockSize;
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if(cb <= 0) throw new InvalidOperationException("this.BlockSize");
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m_pBlock = new byte[cb];
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m_iBlockPos = cb;
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}
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public void Dispose()
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{
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Dispose(true);
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GC.SuppressFinalize(this);
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}
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protected virtual void Dispose(bool bDisposing)
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{
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if(bDisposing)
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{
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MemUtil.ZeroByteArray(m_pBlock);
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m_iBlockPos = m_pBlock.Length;
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}
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}
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protected void InvalidateBlock()
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{
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m_iBlockPos = m_pBlock.Length;
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}
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protected abstract void NextBlock(byte[] pBlock);
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public void Encrypt(byte[] m, int iOffset, int cb)
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{
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if(m == null) throw new ArgumentNullException("m");
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if(iOffset < 0) throw new ArgumentOutOfRangeException("iOffset");
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if(cb < 0) throw new ArgumentOutOfRangeException("cb");
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if(iOffset > (m.Length - cb)) throw new ArgumentOutOfRangeException("cb");
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int cbBlock = m_pBlock.Length;
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while(cb > 0)
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{
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Debug.Assert(m_iBlockPos <= cbBlock);
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if(m_iBlockPos == cbBlock)
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{
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NextBlock(m_pBlock);
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m_iBlockPos = 0;
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}
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int cbCopy = Math.Min(cbBlock - m_iBlockPos, cb);
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Debug.Assert(cbCopy > 0);
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MemUtil.XorArray(m_pBlock, m_iBlockPos, m, iOffset, cbCopy);
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m_iBlockPos += cbCopy;
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iOffset += cbCopy;
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cb -= cbCopy;
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}
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}
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public void Decrypt(byte[] m, int iOffset, int cb)
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{
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Encrypt(m, iOffset, cb);
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}
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}
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}
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