ion Constant 44
#define MD5_T45  0xd9d4d039 //Transformation Constant 45
#define MD5_T46  0xe6db99e5 //Transformation Constant 46
#define MD5_T47  0x1fa27cf8 //Transformation Constant 47
#define MD5_T48  0xc4ac5665 //Transformation Constant 48

//Transformation Constants - Round 4
#define MD5_T49  0xf4292244 //Transformation Constant 49
#define MD5_T50  0x432aff97 //Transformation Constant 50
#define MD5_T51  0xab9423a7 //Transformation Constant 51
#define MD5_T52  0xfc93a039 //Transformation Constant 52
#define MD5_T53  0x655b59c3 //Transformation Constant 53
#define MD5_T54  0x8f0ccc92 //Transformation Constant 54
#define MD5_T55  0xffeff47d //Transformation Constant 55
#define MD5_T56  0x85845dd1 //Transformation Constant 56
#define MD5_T57  0x6fa87e4f //Transformation Constant 57
#define MD5_T58  0xfe2ce6e0 //Transformation Constant 58
#define MD5_T59  0xa3014314 //Transformation Constant 59
#define MD5_T60  0x4e0811a1 //Transformation Constant 60
#define MD5_T61  0xf7537e82 //Transformation Constant 61
#define MD5_T62  0xbd3af235 //Transformation Constant 62
#define MD5_T63  0x2ad7d2bb //Transformation Constant 63
#define MD5_T64  0xeb86d391 //Transformation Constant 64


//Null data (except for first BYTE) used to finalise the checksum calculation
static unsigned char PADDING[64] = {
  0x80, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
  0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
  0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0
};
2、CountChecksum.h（md5校验和类的头文件）
class CMD5Checksum  
{
public:
//interface functions for the RSA MD5 calculation
static CString GetMD5(BYTE* pBuf, UINT nLength);
static CString GetMD5(CFile& File);
static CString GetMD5(const CString& strFilePath);

protected:
//constructor/destructor
CMD5Checksum();
virtual ~CMD5Checksum() {};

//RSA MD5 implementation
void Transform(BYTE Block[64]);
void Update(BYTE* Input, ULONG nInputLen);
CString Final();
inline DWORD RotateLeft(DWORD x, int n);
inline void FF( DWORD& A, DWORD B, DWORD C, DWORD D, DWORD X, DWORD S, DWORD T);
inline void GG( DWORD& A, DWORD B, DWORD C, DWORD D, DWORD X, DWORD S, DWORD T);
inline void HH( DWORD& A, DWORD B, DWORD C, DWORD D, DWORD X, DWORD S, DWORD T);
inline void II( DWORD& A, DWORD B, DWORD C, DWORD D, DWORD X, DWORD S, DWORD T);

//utility functions
void DWordToByte(BYTE* Output, DWORD* Input, UINT nLength);
void ByteToDWord(DWORD* Output, BYTE* Input, UINT nLength);

private:
BYTE  m_lpszBuffer[64];  //input buffer
ULONG m_nCount;   //number of bits, modulo 2^64 (lsb first)
ULONG m_lMD5;   //MD5 checksum
};

#endif // !defined(AFX_MD5CHECKSUM_H__2BC7928E_4C15_11D3_B2EE_A4A60E20D2C3__INCLUDED_)
3、CountChecksum.cpp