Set the handle of authentication window of RSACryptoServiceProvider

Question

I am signing a string through RSACryptoServiceProvider, using a digital certificate as key.

this process is done inside a COM dll, called from a delphi application.

in the choice of the certificate it is possible to pass the handle through the method:

scollection = X509Certificate2UI.SelectFromCollection (fcollection, "Available digital certificate (s)", "Select digital certificate", X509SelectionFlag.SingleSelection, ptr);

but in the authentication screen I could not do something similar, can anyone help me with this?

Answer 1

Assuming you mean you want a PIN or consent prompt parented to some HWND, you want something like

private static RSACryptoServiceProvider AssociateHwnd(
    RSACryptoServiceProvider rsaCsp,
    IntPtr hwnd)
{
    CspKeyContainerInfo containerInfo = rsaCsp.CspKeyContainerInfo;

    CspParameters newParameters = new CspParameters(
        containerInfo.ProviderType,
        containerInfo.ProviderName,
        containerInfo.KeyContainerName)
    {
        KeyNumber = (int)containerInfo.KeyNumber,
        Flags = CspProviderFlags.UseExistingKey,
        ParentWindowHandle = hwnd,
    };

    if (containerInfo.MachineKeyStore)
    {
        newParameters.Flags |= CspProviderFlags.UseMachineKeyStore;
    }

    return new RSACryptoServiceProvider(newParameters);
}

Note that this code assumes you have .NET 4.7 as the runtime, using the easy path described in https://learn.microsoft.com/en-us/dotnet/framework/migration-guide/mitigation-cspparameters-parentwindowhandle-expects-an-hwnd.