[Release]IGC.dll S18.EncDec ComputerCrc+Src

[ZeCoder]

IGC Client DecryptFile Func from IGC.dll

IGC.dll Version:18.1.3.17

void DecryptIGCClientBuffer(unsigned char* m_byBuffer, int iSize)
{
    int v2; // eax
    int i; // esi
    int v5; // ecx
    int v6; // eax
    int v7; // edx
    int v8; // ecx
    int v9; // edx
    int v10; // ecx
    int v11; // edx
    int v12; // ecx
    int v13; // edx

    v2 = 0;
    for (i = iSize - 1; i >= 0; --i)
    {
        v5 = *m_byBuffer++;
        v6 = (v5 << 8) ^ v2;
        v7 = (2 * v6) ^ 0x10213465;
        if ((v6 & 0x8000) == 0)
            v7 = 2 * v6;
        v8 = (2 * v7) ^ 0x10213465;
        if ((v7 & 0x8000) == 0)
            v8 = 2 * v7;
        v9 = (2 * v8) ^ 0x10213465;
        if ((v8 & 0x8000) == 0)
            v9 = 2 * v8;
        v10 = (2 * v9) ^ 0x10213465;
        if ((v9 & 0x8000) == 0)
            v10 = 2 * v9;
        v11 = (2 * v10) ^ 0x10213465;
        if ((v10 & 0x8000) == 0)
            v11 = 2 * v10;
        v12 = (2 * v11) ^ 0x10213465;
        if ((v11 & 0x8000) == 0)
            v12 = 2 * v11;
        v13 = (2 * v12) ^ 0x10213465;
        if ((v12 & 0x8000) == 0)
            v13 = 2 * v12;
        v2 = (2 * v13) ^ 0x10213465;
        if ((v13 & 0x8000) == 0)
            v2 = 2 * v13;
    }
}

void DecryptIGCClientFile(const char* fileName)
{
    FILE* fp = fopen(fileName, "rb");
    if (fp == nullptr) return;
    fseek(fp, 0, SEEK_END);
    int iSize = ftell(fp);
    fseek(fp, 0, SEEK_SET);
    unsigned char* decBuffer = new unsigned char[iSize];
    fread(decBuffer, 1, iSize, fp);
    DecryptIGCClientBuffer(decBuffer, iSize);
    fclose(fp);
    unsigned char tempBuffer[8192 + 1024] = {0};
    memcpy(tempBuffer, decBuffer, iSize);
}

==============Good luck for u=============

If you like it, please like it. :d

I m sorry to that,this code not decrypt file,my mistake,sorry,it should be ComputerCrc,src as follow:

DWORD __fastcall CEncDec::ComputeCRC(BYTE* data, int size)
{
    int crc, i;

    crc = 0;

    BYTE* ptr = data;
    int count = size;

    while(--count >= 0)
    {
        crc = crc ^ (int)*ptr++ << 8;
        for(i = 0; i < 8; ++i)
            if(crc & 0x8000)
                crc = crc << 1 ^ 0x10213465;
            else
                crc = crc << 1;
    }

    return (crc & 0xFFFFFFFF);
}

DWORD __fastcall CEncDec::ComputeFileCRC(char* file)
{
    FILE* hFile = fopen(file, "rb");

    if(!hFile)
        return 0;

    fseek(hFile, 0, SEEK_END);
    long size = ftell(hFile);
    fseek(hFile, 0, SEEK_SET);

    BYTE* buff = new BYTE[size];
    fread(buff, 1, size, hFile);

    DWORD crc = ComputeCRC(buff, size);

    fclose(hFile);
    delete [] buff;

    return crc;
}