Two things that I'm trying to achieve: Creating the signing keys when starting a server. And being able to have access to the original signing key so that it can be used in other libraries (e.g for ramosbugs/oauth2-rs#274).

I'm currently creating the keys myself to achieve this. They are then converted to PEM to be read from PEM again in
CoreRsaPrivateSigningKey::from_pem. I'm also forced to store both versions of the same key separately.

let rs256_signing_key = rsa::pkcs1v15::SigningKey::new(RsaPrivateKey::new(&mut csprng, 2048)?);
let oidc_rs256_signing_key = CoreRsaPrivateSigningKey::from_pem(&rs256_signing_key.to_pkcs1_pem(Default::default())?, None)?;

As such, I would like the ability for CoreRsaPrivateSigningKey to provide a new_random constructor, but also a method which exposes the inner signing key. Perhaps unified under PrivateSigningKey trait methods. Doing so removes the need for users to pull in a bunch of crypto-dependencies themselves, whilst still being able to reuse the private signing in other parts of the rust ecosystem.

I would be more than happy to create PRs myself if these features would be appreciated.