/// <https://spec.torproject.org/dir-spec/server-descriptor-format.html#item:ntor-onion-key-crosscert>
/// <https://spec.torproject.org/dir-spec/server-descriptor-format.html#item:hidden-service-dir>
/// <https://spec.torproject.org/dir-spec/server-descriptor-format.html#item:router-sig-ed25519>
let tap_onion_key: Option<ll::pk::rsa::PublicKey> = if let Some(tok) = body.get(ONION_KEY) {