I'm creating an OpenID Server, what do I return from the jwks request

Question

I have a working webapp that acts as an OAuth2/OpenID server.

It is all working fine with many clients, but I have come across a new client that requires the jwks endpoint to work.

My server uses HS256 for signing, using the client secret as the key. I have Googled for over an hour, trying to find out what the jwks endpoint should return in this situation, but I haven't been able to find any concrete examples using HS256.

I am also baffled by the jwks endpoint is supposed to return a key, but the key actually used depends on which client it is (as it is the client secret), but the endpoint doesn't know which client is connecting.

Can anyone suggest where to find an example that will work?