Thread: CRC / checksum

I'm a newbie to C++ so bare with me please. I’ve read FAQs and documents on CRC but nothing covers what I want to do. Nothing that I've found anyway

I would like to read several binary files into my client hook for TFC and get their CRC values. Then I would like to check the values each file generated against a table of accepted values for that file.

It’s a simple form of cheat protection. If the client is found to have a file that does not match one of the accepted values the hook can take required action.

Is this a silly idea? Are there any better methods?


This is the crc.h that comes with the HL SDK

Code:

#ifndef CRC_H
#define CRC_H
#ifdef _WIN32
#pragma once
#endif

// MD5 Hash
typedef struct
{
	unsigned int buf[4];
    unsigned int bits[2];
    unsigned char in[64];
} MD5Context_t;


typedef unsigned long CRC32_t;
void CRC32_Init(CRC32_t *pulCRC);
CRC32_t CRC32_Final(CRC32_t pulCRC);
void CRC32_ProcessBuffer(CRC32_t *pulCRC, void *p, int len);
void CRC32_ProcessByte(CRC32_t *pulCRC, unsigned char ch);
int CRC_File(CRC32_t *crcvalue, char *pszFileName);

unsigned char COM_BlockSequenceCRCByte (unsigned char *base,
        int length, int sequence);

void MD5Init(MD5Context_t *context);
void MD5Update(MD5Context_t *context, unsigned char const *buf,
               unsigned int len);
void MD5Final(unsigned char digest[16], MD5Context_t *context);
void Transform(unsigned int buf[4], unsigned int const in[16]);

int MD5_Hash_File(unsigned char digest[16], char *pszFileName, int bUsefopen,
        int bSeed, unsigned int seed[4]);
char *MD5_Print(unsigned char hash[16]);
int MD5_Hash_CachedFile(unsigned char digest[16], unsigned char *pCache,
        int nFileSize, int bSeed, unsigned int seed[4]);

int CRC_MapFile(CRC32_t *crcvalue, char *pszFileName);

#endif