[MS Crypt API][原]计算文件hashParam

#define    SAIO_CSP                              "SAIO SignCSP"typedef enum  Em_Algorithm_TYPE{    AlgorithmType_SHA1    = 1,    AlgorithmType_SHA256  = 2}ALGORITHM_TYPE, *PALGORITHM_TYPE;BOOL GetFileHashParam(LPCSTR lpszCataFileName, PBYTE pbyHash, PDWORD pdwHashLen, ALGORITHM_TYPE emAlAlgorithmType){    BOOL bRet = FALSE;    HCRYPTPROV hProv = 0;    HCRYPTHASH hHash = 0;    HCRYPTKEY hKey = 0;    HANDLE hFile = NULL;    DWORD dwFileSize = 0, len;    BYTE byTempBuf[2049] = {0};    hFile = CreateFile(lpszCataFileName, GENERIC_READ, 0, NULL, OPEN_EXISTING, FILE_ATTRIBUTE_NORMAL, NULL);    if (INVALID_HANDLE_VALUE == hFile)    {        return FALSE;    }    DWORD  dwProvType = PROV_RSA_AES;    ALG_ID hashAlgo = CALG_SHA_256;    if (AlgorithmType_SHA1 == emAlAlgorithmType)    {        dwProvType = PROV_RSA_FULL;        hashAlgo = CALG_SHA1;    }    if (!CryptAcquireContext(&hProv, SAIO_CSP, NULL, dwProvType, 0))     {        if (GetLastError() == NTE_BAD_KEYSET)        {            if(!CryptAcquireContext(&hProv,SAIO_CSP,NULL, PROV_RSA_FULL, CRYPT_NEWKEYSET))             {                goto HashExit;            }        }    }    //     //     Create a hash object.    //         DWORD dwError = 0;    if ( !CryptCreateHash(hProv, hashAlgo ,0 ,0 ,&hHash))    {        dwError = GetLastError();        goto HashExit;    }    dwFileSize = GetFileSize(hFile, NULL);    while(dwFileSize != 0)    {        bRet = ReadFile(hFile, byTempBuf, 2048, &len, NULL);        //         //     Check for end of file.         //             if (bRet && len==0)        {            break;        }        CryptHashData(hHash, byTempBuf, len, 0);        dwFileSize -= len;    }    if (hFile != NULL)    {        CloseHandle(hFile);    }    len = 0;    DWORD dwCount = sizeof(DWORD);    if(!CryptGetHashParam(hHash, HP_HASHSIZE, (BYTE*)pdwHashLen, &dwCount, 0))    {        *pdwHashLen = 0;    }    else    {        if (!CryptGetHashParam(hHash, HP_HASHVAL, pbyHash, pdwHashLen, 0))        {            *pdwHashLen = 0;        }    }    if (*pdwHashLen != 20        && *pdwHashLen != 32)    {        bRet = FALSE;    }HashExit:      if (hKey != NULL)    {        CryptDestroyKey(hKey);    }    if (hHash != NULL)    {        CryptDestroyHash(hHash);    }    if (hProv != NULL)    {        CryptReleaseContext(hProv, 0);    }    return bRet;}