Function server_receive_intro_no_keygen 

fn server_receive_intro_no_keygen(
    y: &StaticSecret,
    k_hss_ntor: &HsSvcNtorKeypair,
    auth_key: &HsIntroPtSessionIdKey,
    subcredential: &[Subcredential],
    intro_header: &[u8],
    msg: &[u8],
) -> Result<(HsNtorHkdfKeyGenerator, Vec<u8>, Vec<u8>)>

Helper: Like server_receive_intro, but take an ephemeral key rather than a RNG.