一点一滴解读网狐的加解密(4)

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//随机映射WORD CServerSocketItem::SeedRandMap(WORD wSeed){        DWORD dwHold = wSeed;        return (WORD)((dwHold = dwHold * 241103L + 2533101L) >> 16);}//映射发送数据BYTE CServerSocketItem::MapSendByte(BYTE const cbData){        BYTE cbMap = g_SendByteMap[(BYTE)(cbData+m_cbSendRound)];        m_cbSendRound += 3;        return cbMap;}//映射接收数据BYTE CServerSocketItem::MapRecvByte(BYTE const cbData){        BYTE cbMap = g_RecvByteMap[cbData] - m_cbRecvRound;        m_cbRecvRound += 3;        return cbMap;}

//加密数据WORD CServerSocketItem::EncryptBuffer(BYTE pcbDataBuffer[], WORD wDataSize, WORD wBufferSize){        WORD i = 0;        //效验参数        ASSERT(wDataSize >= sizeof(TCP_Head));        ASSERT(wDataSize <= (sizeof(TCP_Head) + SOCKET_TCP_BUFFER));        ASSERT(wBufferSize >= (wDataSize + 2*sizeof(DWORD)));        //调整长度        WORD wEncryptSize = wDataSize - sizeof(TCP_Info), wSnapCount = 0;        if ((wEncryptSize % sizeof(DWORD)) != 0)        {                wSnapCount = sizeof(DWORD) - wEncryptSize % sizeof(DWORD);                memset(pcbDataBuffer + sizeof(TCP_Info) + wEncryptSize, 0, wSnapCount);        }        //效验码与字节映射        BYTE cbCheckCode = 0;        for (i = sizeof(TCP_Info); i < wDataSize; i++)        {                cbCheckCode += pcbDataBuffer;                pcbDataBuffer = MapSendByte(pcbDataBuffer);        }        //填写信息头        TCP_Head * pHead = (TCP_Head *)pcbDataBuffer;        pHead->TCPInfo.cbCheckCode = ~cbCheckCode + 1;        pHead->TCPInfo.wPacketSize = wDataSize;        pHead->TCPInfo.cbVersion = SOCKET_TCP_VER;        //加密数据        DWORD dwXorKey = m_dwSendXorKey;        WORD * pwSeed = (WORD *)(pcbDataBuffer + sizeof(TCP_Info));        DWORD * pdwXor = (DWORD *)(pcbDataBuffer + sizeof(TCP_Info));        WORD wEncrypCount = (wEncryptSize + wSnapCount) / sizeof(DWORD);        for (i = 0; i < wEncrypCount; i++)        {                *pdwXor++ ^= dwXorKey;                dwXorKey = SeedRandMap(*pwSeed++);                dwXorKey |= ((DWORD)SeedRandMap(*pwSeed++)) << 16;                dwXorKey ^= g_dwPacketKey;        }        //设置变量        m_dwSendPacketCount++;        m_dwSendXorKey = dwXorKey;        return wDataSize;}//解密数据WORD CServerSocketItem::CrevasseBuffer(BYTE pcbDataBuffer[], WORD wDataSize){        WORD i = 0;        //效验参数        ASSERT(wDataSize >= sizeof(TCP_Head));        ASSERT(((TCP_Head *)pcbDataBuffer)->TCPInfo.wPacketSize == wDataSize);        //调整长度        WORD wSnapCount = 0;        if ((wDataSize % sizeof(DWORD)) != 0)        {                wSnapCount = sizeof(DWORD) - wDataSize % sizeof(DWORD);                memset(pcbDataBuffer + wDataSize, 0, wSnapCount);        }        //提取密钥        if (m_dwRecvPacketCount == 0)        {                ASSERT(wDataSize >= (sizeof(TCP_Head) + sizeof(DWORD)));                if (wDataSize < (sizeof(TCP_Head) + sizeof(DWORD))) throw TEXT("数据包解密长度错误");                m_dwRecvXorKey = *(DWORD *)(pcbDataBuffer + sizeof(TCP_Head));                m_dwSendXorKey = m_dwRecvXorKey;                MoveMemory(pcbDataBuffer + sizeof(TCP_Head), pcbDataBuffer + sizeof(TCP_Head) + sizeof(DWORD),                           wDataSize - sizeof(TCP_Head) - sizeof(DWORD));                wDataSize -= sizeof(DWORD);                ((TCP_Head *)pcbDataBuffer)->TCPInfo.wPacketSize -= sizeof(DWORD);        }        //解密数据        DWORD dwXorKey = m_dwRecvXorKey;        DWORD * pdwXor = (DWORD *)(pcbDataBuffer + sizeof(TCP_Info));        WORD  * pwSeed = (WORD *)(pcbDataBuffer + sizeof(TCP_Info));        WORD wEncrypCount = (wDataSize + wSnapCount - sizeof(TCP_Info)) / 4;        for (i = 0; i < wEncrypCount; i++)        {                if ((i == (wEncrypCount - 1)) && (wSnapCount > 0))                {                        BYTE * pcbKey = ((BYTE *) & m_dwRecvXorKey) + sizeof(DWORD) - wSnapCount;                        CopyMemory(pcbDataBuffer + wDataSize, pcbKey, wSnapCount);                }                dwXorKey = SeedRandMap(*pwSeed++);                dwXorKey |= ((DWORD)SeedRandMap(*pwSeed++)) << 16;                dwXorKey ^= g_dwPacketKey;                *pdwXor++ ^= m_dwRecvXorKey;                m_dwRecvXorKey = dwXorKey;        }        //效验码与字节映射        TCP_Head * pHead = (TCP_Head *)pcbDataBuffer;        BYTE cbCheckCode = pHead->TCPInfo.cbCheckCode;;        for (i = sizeof(TCP_Info); i < wDataSize; i++)        {                pcbDataBuffer = MapRecvByte(pcbDataBuffer);                cbCheckCode += pcbDataBuffer;        }        if (cbCheckCode != 0) throw TEXT("数据包效验码错误");        return wDataSize;}