Abstract:

Whether or not parallel repetition improves security, is a fundamental 
question in the study of protocols. While parallel repetition
improves the security of 3-message protocols and of public-coin protocols,
Bellare, Impagliazzo and Naor (FOCS '97) gave an example of a protocol for
which parallel repetition does not improve the security at all.
We show that by slightly modifying any protocol, in a way that preserves its
other properties, we get a protocol for which parallel repetition does
improve the security (to any degree) .

In the second part of the talk (if time permits), I will presents our recent
results on basing cryptography on minimal hardness assumptions, where we
give simpler and more efficient (in some cases tight)  constructions of
pseudorandom generators, statistically hiding commitments and universal
one-way hash functions based on one-way functions.