Electronic bearer certificates and protecting scarce online resources.

 https://web.archive.org/web/20150812055200/http://szabo.best.vwh.net/

The new paradigm of very highly probable, rather than absolutely certain, security has led to a raft of new possibilities for securing distributed applications. For the first time we can implement on the Internet crucial integrity properties and applications -- including synchronized clocks, unforgeable transactions, and censorship-proof publishing.