conclusion.tex

\section{Conclusion}

We introduced two new properties of ledger protocols:
Timeliness and supersafety. Timeliness mandates that transactions are
recorded on ledgers with a timestamp that roughly corresponds to the
current real time. Supersafety mandates that all parties
report ledgers that are identical to each other at every moment.
We proved that all popular blockchain
deployments attain timeliness under the assumption
that clocks are synchronized, and the network is synchronous.
We also showed that the synchrony assumption is a necessary condition.
We reduced supersafety to timeliness and
vice versa.
Our final protocol is live, supersafe, perfectly timely,
and has support for late-joining clients. Applying both our reductions
in series to \emph{any} blockchain protocol with safety, liveness, timeliness and client support
allows transforming it into a protocol that additionally enjoys supersafety and perfect timeliness.
We hope that the nomenclature developed in this paper will shed some light on the constituent parts
of security proofs of previous protocols and simplify the design of
future ones.