It's currently not possible with OTP's crypto module to generate an RSA key. It would be useful to have an interface to this to avoid having to ship with a NIF for applications that needs access to RSA key generation.
The function to generate an RSA key should take the key size (in bits) and the public exponent.
I will happily implement this if the OTP team believes this would be a useful addition. I'm unsure if the `crypto:compute_key/4` function should be extended to also work with RSA or if it should remain as a function used for shared secret computations.