93 lines
2.1 KiB
C++
93 lines
2.1 KiB
C++
/*
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EQ2Emulator: Everquest II Server Emulator
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Copyright (C) 2007 EQ2EMulator Development Team (http://www.eq2emulator.net)
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This file is part of EQ2Emulator.
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EQ2Emulator 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 3 of the License, or
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(at your option) any later version.
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EQ2Emulator 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 EQ2Emulator. If not, see <http://www.gnu.org/licenses/>.
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*/
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#include "RC4.h"
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#include <string.h>
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static bool g_bInitStateInitialized = false;
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static uchar g_byInitState[256];
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RC4::RC4(int64 nKey)
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{
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if( !g_bInitStateInitialized )
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{
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for(int16 i = 0; i < 256; i++ )
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g_byInitState[i] = i;
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}
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Init(nKey);
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}
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RC4::~RC4()
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{
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}
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void RC4::Init(int64 nKey)
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{
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memcpy(m_state, g_byInitState, 256);
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m_x = 0;
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m_y = 0;
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ulong dwKeyIndex = 0;
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ulong dwStateIndex = 0;
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uchar* pKey = (uchar*)&nKey;
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for(int16 i = 0; i < 256; i++ )
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{
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ulong dwTemp = m_state[i];
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dwStateIndex += pKey[dwKeyIndex] + dwTemp;
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dwStateIndex &= 0xFF;
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m_state[i] = m_state[dwStateIndex];
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m_state[dwStateIndex] = (uchar)dwTemp;
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dwKeyIndex++;
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dwKeyIndex &= 7;
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}
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}
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// A = m_state[X + 1]
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// B = m_state[Y + A]
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// C ^= m_state[(A + B)]
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// X = 20
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// Y = ?
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// C = 0
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// m_state[(A + B)] = Cypher Byte
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void RC4::Cypher(uchar* pBuffer, int32 nLength)
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{
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int32 nOffset = 0;
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uchar byKey1 = m_x;
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uchar byKey2 = m_y;
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if( nLength > 0 )
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{
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do
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{
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byKey1++;
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uchar byKeyVal1 = m_state[byKey1];
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byKey2 += byKeyVal1;
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uchar byKeyVal2 = m_state[byKey2];
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m_state[byKey1] = byKeyVal2;
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m_state[byKey2] = byKeyVal1;
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pBuffer[nOffset++] ^= m_state[(byKeyVal1 + byKeyVal2) & 0xFF];
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} while( nOffset < nLength );
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}
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m_x = byKey1;
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m_y = byKey2;
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}
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