+function generate_dialback(id, to, from)
+ return sha256_hash(id..to..from..hosts[from].dialback_secret, true);
+end
+
+function initiate_dialback(session)
+ -- generate dialback key
+ session.dialback_key = generate_dialback(session.streamid, session.to_host, session.from_host);
+ session.sends2s(st.stanza("db:result", { from = session.from_host, to = session.to_host }):text(session.dialback_key));
+ session.log("info", "sent dialback key on outgoing s2s stream");
+end
+
+function verify_dialback(id, to, from, key)
+ return key == generate_dialback(id, to, from);
+end
+