Usb key插入检测，并动态获取CSP

    int                  ret = 0;
    HRESULT           hr = S_OK;
    LPTSTR            szReaders = NULL, szRdr = NULL;
    DWORD             cchReaders = SCARD_AUTOALLOCATE;
    DWORD             dwI, dwRdrCount;
    SCARD_READERSTATE rgscState[MAXIMUM_SMARTCARD_READERS];
    TCHAR             szCard[MAX_PATH * 64];
    DWORD              dwCardLen = sizeof(szCard)/sizeof(TCHAR);
    SCARDCONTEXT      hSC;
    LONG              lReturn;

    // Establish a context.
    lReturn = SCardEstablishContext(SCARD_SCOPE_USER,
        NULL,
        NULL,
        &hSC );
    if ( SCARD_S_SUCCESS != lReturn )
    {
        goto cleanup;
    }

    // Determine which readers are available.
    lReturn = SCardListReaders(hSC,
        NULL,
        (LPTSTR)&szReaders,
        &cchReaders );
    if ( SCARD_S_SUCCESS != lReturn )
    {
        goto cleanup;
    }

    // Place the readers into the state array.
    szRdr = szReaders;
    for ( dwI = 0; dwI < MAXIMUM_SMARTCARD_READERS; dwI++ )
    {
        if ( 0 == *szRdr )
            break;
        rgscState[dwI].szReader = szRdr;
        rgscState[dwI].dwCurrentState = SCARD_STATE_UNAWARE;
        szRdr += lstrlen(szRdr) + 1;
    }
    dwRdrCount = dwI;

    lReturn = SCardListCards(hSC, NULL, NULL, 0, szCard, &dwCardLen);
    if (SCARD_S_SUCCESS != lReturn)
    {

        goto cleanup;
    }
    // If any readers are available, proceed.
    if ( 0 != dwRdrCount )
    {
        for (;;)
        { 
            // Look for the card.
            lReturn = SCardLocateCards(hSC,
                szCard,
                rgscState,
                dwRdrCount );
            if ( SCARD_S_SUCCESS != lReturn )
            {
                 goto cleanup;
            }

            // Look through the array of readers.
            for ( dwI=0; dwI < dwRdrCount; dwI++)
            {
                if ( 0 != ( SCARD_STATE_ATRMATCH & 
                    rgscState[dwI].dwEventState))
                {

                    lReturn = SCardListCards(hSC, rgscState[dwI].rgbAtr, NULL, 0, szCard, &dwCardLen);
                    LPTSTR szProvider = NULL;
                    DWORD  chProvider = SCARD_AUTOALLOCATE;
                    LONG   lReturn = SCARD_S_SUCCESS;

                    lReturn=SCardGetCardTypeProviderName(hSC,szCard,SCARD_PROVIDER_CSP,(LPTSTR)&szProvider,&chProvider);

                    ret = 1;
                    goto cleanup;  // Context will be release automatically.
                }
                // Update the state.
                rgscState[dwI].dwCurrentState = rgscState[dwI].dwEventState;
            }

            // Card not found yet; wait until there is a change.
            lReturn = SCardGetStatusChange(hSC,
                1000, // time wait
                rgscState,
                dwRdrCount );
            if ( SCARD_S_SUCCESS != lReturn )
            {
                                goto cleanup;
            }
        }  // for (;;)
    }

cleanup:
    if (szReaders)
        SCardFreeMemory(hSC,szReaders);

    if (hSC)
        SCardReleaseContext(hSC);

    return ret;