ICEnroll::enumProviders [C++]

CEnroll.enumProviders [Visual Basic]

The enumProviders method enumerates all providers available on the computer for the specified ProviderType property. If that property has not been changed, then it has a default value of one, as set in the registry. This means PROV_RSA_FULL for the default Microsoft Base Cryptographic Provider is used for the enumeration.

[Visual Basic]
objEnroll.enumProviders( _
            dwIndex As Long, _
            dwFlags As Long ) As String
[C++]
HRESULT enumProviders (
  DWORD dwIndex,         // in
  DWORD dwFlags,         // in
  BSTR *pbstrProvName    // out
);

Parameters

[Visual Basic] objEnroll

Object expression that resolves to a CEnroll object.

[Visual Basic,C++] dwIndex

Specifying zero for dwIndex gets the first provider. Increment dwIndex for successive providers. When there are no more providers, ERROR_NO_MORE_ITEMS is returned for C++, and it is triggered for Visual Basic.

[Visual Basic,C++] dwFlags

These flags are passed through to CryptEnumProviders. See it for details.

[C++] pbstrProvName

Pointer to BSTR variable to receive the name of the provider being enumerated. It is the responsibility of the caller to free this variable (via SysFreeString).

Return Values

[Visual Basic] The return value is a String variable representing the name of the provider being enumerated. An exception is raised if an error is encountered or when there are no more items remaining in the enumeration sequence.

[C++] The return value is an HRESULT. A value of S_OK indicates success. Upon successful completion of this function, pbstrProviderName will contain the name of the enumerated provider. When there are no more providers, the value ERROR_NO_MORE_ITEMS is returned.

Example Code [C++]

BSTR       bstrProvName = NULL;
DWORD      dwType, nProv;
int        j;
HRESULT    hr;

// array of CSP provider types (see wincrypt.h)
DWORD      nProvType[] = { PROV_RSA_FULL,      
                           PROV_RSA_SIG,       
                           // list shortened for brevity
                           //...
                           PROV_STT_ISS };

// Loop, for each Prov Type
for ( j = 0; j < ( sizeof( nProvType ) / sizeof( DWORD ) ); j++ )
{
    nProv = 0;
    
    // check specific prov type
    dwType = nProvType[j];
    // pEnroll is previously instantiated ICEnroll interface pointer
    hr = pEnroll->put_ProviderType( dwType );
    if ( FAILED(hr))
    {
        printf("Failed put_ProviderType - %x\n", hr);
        goto error;
    }
    // enumerate the CSPs of this type
    while ( S_OK == ( hr  = pEnroll->enumProviders(nProv,
                                                   0,
                                                   &bstrProvName)))
    {
        printf("Provider %ws (type %d )\n", bstrProvName, dwType );
        // increment the index
        nProv++;
        // Free this string, so it can be re-used.
        if ( NULL != bstrProvName )
        {
            SysFreeString( bstrProvName );
            bstrProvName = NULL;
        }
    }
    // Print message if provider type doesn't have any CSPs.
    if ( 0 == nProv )
       printf("There were no CSPs of type %d\n", dwType );
}

error:
// Clean up resources, etc.
if ( NULL != pEnroll )
       pEnroll->Release();
if ( NULL != bstrProvName )
    SysFreeString( bstrProvName );

CoUninitialize();

Example Code [Visual Basic]

Dim strOut As String
Dim i As Integer
Dim NoMoreRecs As Boolean

    ' enumerate the providers
    i = 0
    NoMoreRecs = False
    On Error GoTo ErrorHandler
    Do
        strOut = objEnroll.enumProviders(i, 0)
        If NoMoreRecs Then
            Exit Do
        End If
        ' display the index and Provider value
        MsgBox (i & " " & strOut)
        i = i + 1
    Loop

    Exit Sub

ErrorHandler:

    NoMoreRecs = True
    Resume Next

    End Sub

Requirements

  Windows NT/2000: Requires Windows 2000 (or Windows NT 4.0 with the Windows NT 4.0 Option Pack).
  Header: Declared in Xenroll.h.
  Library: Use Uuid.lib.

See Also

ProviderType