Re: native MD5 API?

"George" <George@discussions.microsoft.com> ha scritto nel messaggio
news:6E37789F-9FC8-4081-A575-E0324BFDF179@microsoft.com...


I have no idea about patrick's referenced APIs.

However, you can go here:

Example C Program: Creating an MD-5 Hash from File Content

http://msdn.microsoft.com/en-us/library/aa382380(VS.85).aspx

and find a C sample source code to compute MD5 hash.

(Note that if you follow Alex's first suggestion in this thread, you can
arrive at this MSDN source code.)

So, the interesting APIs should be:

CryptAcquireContext
CryptCreateHash
CryptHashData
CryptDestroyHash
CryptReleaseContext
CryptGetHashParam

Here's the code:

<code>
 #include <stdio.h>
#include <windows.h>
#include <Wincrypt.h>

#define BUFSIZE 1024
#define MD5LEN 16

DWORD main(int argc, char *argv[])
{
    DWORD dwStatus = 0;
    BOOL bResult = FALSE;
    HCRYPTPROV hProv = 0;
    HCRYPTHASH hHash = 0;
    HANDLE hFile = NULL;
    BYTE rgbFile[BUFSIZE];
    DWORD cbRead = 0;
    BYTE rgbHash[MD5LEN];
    DWORD cbHash = 0;
    CHAR rgbDigits[] = "0123456789abcdef";

    // Copyright (c) Microsoft Corporation. All rights reserved.
    // Logic to check usage goes here.

    hFile = CreateFile(argv[1],
        GENERIC_READ,
        FILE_SHARE_READ,
        NULL,
        OPEN_EXISTING,
        FILE_FLAG_SEQUENTIAL_SCAN,
        NULL);

    if (INVALID_HANDLE_VALUE == hFile)
    {
        dwStatus = GetLastError();
        printf("Error opening file %s\nError: %d\n", argv[1],
            dwStatus);
        return dwStatus;
    }

    // Get handle to the crypto provider
    if (!CryptAcquireContext(&hProv,
        NULL,
        NULL,
        PROV_RSA_FULL,
        CRYPT_VERIFYCONTEXT))
    {
        dwStatus = GetLastError();
        printf("CryptAcquireContext failed: %d\n", dwStatus);
        CloseHandle(hFile);
        return dwStatus;
    }

    if (!CryptCreateHash(hProv, CALG_MD5, 0, 0, &hHash))
    {
        dwStatus = GetLastError();
        printf("CryptAcquireContext failed: %d\n", dwStatus);
        CloseHandle(hFile);
        CryptReleaseContext(hProv, 0);
        return dwStatus;
    }

    while (bResult = ReadFile(hFile, rgbFile, BUFSIZE,
        &cbRead, NULL))
    {
        if (0 == cbRead)
        {
            break;
        }

        if (!CryptHashData(hHash, rgbFile, cbRead, 0))
        {
            dwStatus = GetLastError();
            printf("CryptHashData failed: %d\n", dwStatus);
            CryptReleaseContext(hProv, 0);
            CryptDestroyHash(hHash);
            CloseHandle(hFile);
            return dwStatus;
        }
    }

    if (!bResult)
    {
        dwStatus = GetLastError();
        printf("ReadFile failed: %d\n", dwStatus);
        CryptReleaseContext(hProv, 0);
        CryptDestroyHash(hHash);
        CloseHandle(hFile);
        return dwStatus;
    }

    cbHash = MD5LEN;
    if (CryptGetHashParam(hHash, HP_HASHVAL, rgbHash, &cbHash, 0))
    {
        printf("MD5 hash of file %s is: ", argv[1]);
        for (DWORD i = 0; i < cbHash; i++)
        {
            printf("%c%c", rgbDigits[rgbHash[i] >> 4],
                rgbDigits[rgbHash[i] & 0xf]);
        }
        printf("\n");
    }
    else
    {
        dwStatus = GetLastError();
        printf("CryptGetHashParam failed: %d\n", dwStatus);
    }

    CryptDestroyHash(hHash);
    CryptReleaseContext(hProv, 0);
    CloseHandle(hFile);

    return dwStatus;
}
</code>

HTH,
Giovanni