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;