Implementing SHA1 hash using Windows Cryptography API and C++

Question

_{Friday, December 21, 2012 6:44 AM}

looking for a guidance to Implement SHA1 hash using Windows Cryptography API and C++. Does cryptography API support SHA1 hash

All replies (3)

_{Friday, December 21, 2012 8:23 AM ✅Answered | 1 vote}

>looking for a guidance to Implement SHA1 hash using Windows Cryptography API and C++. Does cryptography API support SHA1 hash

Yes, it does - along with other hashing algorithms. CryptHashData is
the core API you need to use.

Dave

---

_{Friday, December 21, 2012 9:22 PM ✅Answered | 2 votes}

On 12/21/2012 1:44 AM, Deepthi Kalyan wrote:

looking for a guidance to Implement SHA1 hash using Windows Cryptography API and C++. Does cryptography API support SHA1 hash

http://msdn.microsoft.com/en-us/library/windows/desktop/aa382380.aspx

Replace CALG_MD5 with CALG_SHA1, and change the buffer size (MD5LEN) from 16 to 20.

Igor Tandetnik

---

_{Monday, December 24, 2012 12:22 PM ✅Answered}

Modified the changes as suggested. The modified code is 

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

#define BUFSIZE 1024
#define SHA1LEN 20

DWORD main()
{
    DWORD dwStatus = 0;
    BOOL bResult = FALSE;
    HCRYPTPROV hProv = 0;
    HCRYPTHASH hHash = 0;
    HANDLE hFile = NULL;
    BYTE rgbFile[BUFSIZE];
    DWORD cbRead = 0;
    BYTE rgbHash[SHA1LEN];
    DWORD cbHash = 0;
    CHAR rgbDigits[] = "0123456789abcdef";
    LPCTSTR filename=_T("D:\file1.txt");
    // Logic to check usage goes here.

    hFile = CreateFile(filename,
        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", filename, 
            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_SHA1, 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 = SHA1LEN;
    if (CryptGetHashParam(hHash, HP_HASHVAL, rgbHash, &cbHash, 0))
    {
        printf("MD5 hash of file %s is: \n", filename);
        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; 
}