Authenticating the Application

The first step your application must perform is authentication. Authentication verifies the application's identity to Windows Media Device Manager. Once you authenticate your application, you can call QueryInterface to get the root IWMDeviceManager interface, which can be queried for other required interfaces, which can themselves be queried for all other interfaces. Authentication need only take place once, on startup.

To authenticate your application, perform these steps:

1. CoCreate the MediaDevMgr object (class ID MediaDevMgr), and request an IComponentAuthenticate interface.
2. Create a CSecureChannelClient object to handle the authentication.
3. Pass your application key and transfer certificate to the secure channel object. You can use the dummy key/certificate shown in the following example code to get basic functionality from SDK functions. However, to get full functionality (important for passing files to and from the device), you must request a key and certificate from Microsoft as described in Tools for Development.
4. Pass the IComponentAuthenticate interface you created in step 1 to the secure channel object.
5. Call CSecureChannelClient::Authenticate to authenticate your application.
6. Query IComponentAuthenticate for the IWMDeviceManager interface.

These steps are shown in the following C++ code.

HRESULT CWMDMController::Authenticate()
{
    // Use a dummy key/certificate pair to allow basic functionality.
    // An authentic keypair is required for full SDK functionality.
    BYTE abPVK[] = {0x00};
    BYTE abCert[] = {0x00};
    HRESULT hr;
    CComPtr<IComponentAuthenticate> pAuth;

    // Create the WMDM object and acquire 
    // its authentication interface.
    hr = CoCreateInstance(
        __uuidof(MediaDevMgr),
        NULL,
        CLSCTX_INPROC_SERVER,
        __uuidof(IComponentAuthenticate),
        (void**)&pAuth);

    if (FAILED(hr)) return hr;

    // Create the secure channel client class needed to authenticate the application.
    // We'll use a global member variable to hold the secure channel client
    // in case we need to handle encryption, decryption, or MAC verification
    // during this session.
    m_pSAC = new CSecureChannelClient;
    if (m_pSAC == NULL) return E_FAIL;

    // Send the application's transfer certificate and the associated 
    // private key to the secure channel client.
    hr = m_pSAC->SetCertificate(
        SAC_CERT_V1,
        (BYTE *)abCert, sizeof(abCert),
        (BYTE *)abPVK,  sizeof(abPVK));
    if (FAILED(hr)) return hr;
            
    // Send the authentication interface we created to the secure channel 
    // client and authenticate the application with the V1 protocol.
    // (This is the only protocol currently supported.)
    m_pSAC->SetInterface(pAuth);
    hr = m_pSAC->Authenticate(SAC_PROTOCOL_V1);
    if (FAILED(hr)) return hr;

    // Authentication succeeded, so we can use WMDM.
    // Query for the root WMDM interface.
    hr = pAuth->QueryInterface( __uuidof(IWMDeviceManager), (void**)&m_IWMDMDeviceMgr);

    return hr;
}

See Also

• Creating a Windows Media Device Manager Application