Question

I wrote some code using the Microsoft CryptoAPI to calculate a SHA-1 and got the compiled exe working on Windows 7, Win Server 2008, Win Server 2003. However, when I run it under Windows XP SP3, it does not work.

I narrowed down the failure to the CryptAcquireContext() call.

I did notice that a previous post talked about the XP faulty naming of “… (Prototype)” and it must be accounted for by using a WinXP specific macro MS_ENH_RSA_AES_PROV_XP.

I did the XP specific code modifications and it still doesn’t work. (The bResult returns 0 false on Win XP, all other platforms bResult returns 1 true.)

I checked the MS_ENH_RSA_AES_PROV_XP with the actual key+string values I see in regedit.exe so everything looks like it’s set up to work but no success.

Have I overlooked something to make it work on Windows XP?

I’ve pasted shortest possible example to illustrate the issue. I used VS2010 C++.

// based on examples from http://msdn.microsoft.com/en-us/library/ms867086.aspx

#include "windows.h"
#include "wincrypt.h"
#include <iostream>
#include <iomanip>  // for setw()

void main()
{
    BOOL bResult;
    HCRYPTPROV hProv;

    // Attempt to acquire a handle to the default key container.
    bResult = CryptAcquireContext(
        &hProv,            // Variable to hold returned handle.
        NULL,              // Use default key container.
        MS_DEF_PROV,       // Use default CSP.
        PROV_RSA_FULL,     // Type of provider to acquire.
        0);                // No special action.
    std::cout << "line:  " << std::setw(4) << __LINE__ << ";  " << "bResult = " << bResult << std::endl;

    if (! bResult) {        // try Windows XP provider name
        bResult = CryptAcquireContext(
            &hProv,            // Variable to hold returned handle.
            NULL,              // Use default key container.
            MS_ENH_RSA_AES_PROV_XP,  // Windows XP specific instead of using default CSP.
            PROV_RSA_AES,     // Type of provider to acquire.
            0);                // No special action.
        std::cout << "line:  " << std::setw(4) << __LINE__ << ";  " << "bResult = " << bResult << std::endl;
    }

    if (bResult)
        CryptReleaseContext(hProv, 0);
}

Windows 7 success:

Windows XP failure:

Answer 1

In your CryptAcquireContext code, it appears you are missing the parameter to get a context without a specific container set. You need to pass the CRYPT_VERIFYCONTEXT option in CryptAcquireContext.

Windows 7 might be working around this.

http://msdn.microsoft.com/en-us/library/windows/desktop/aa379886(v=vs.85).aspx

For further diagnosis, the results of GetLastError() would be requisite.