Thursday, September 17, Volen 101, 2:00-3.00 pm
Many crucial protocol problems
(such as secret exchange, contract signing, and certified e-mail)
involve a "symultaneous" exchange between JUST TWO parties,
but are cleanly solvable only with the help of a TRUSTED THIRD PARTY,
something that generates
1) congestions (in the network),
2) liabilities (for the third party) and
3) costs (to the users).
We thus put forward and explore the power of an alternative model: two-party protocols with an INVISIBLE TRUSTED PARTY, that is, a party that does not participate in an ordinary execution, but, if something goes wrong, can still take a simple action to complete the execution properly. In particular, we show that Certified-E Mail possesses a clean and practical solution in this model.
Host: Liuba Shrira