Unit4 Identity Services is based on Duende Identity Server.
The OpenID Connect specification recommends a client authentication method based on asymmetric keys. With this approach, instead of transmitting the shared secret over the network, the client creates a JWT and signs it with its private key.
This is a simple Blazor app to show you how a token request can be done in C#, using a private key JWT. It requires that you already have your Client setup in U4IDS.
It is based on the Duende samples found here: Duende sample code (documentation )