Non-interactive zero-knowledge (NIZK) systems are
fundamental cryptographic primitives used in many constructions,
including CCA2-secure cryptosystems, digital signatures, and various
cryptographic protocols. What makes them especially attractive, is
that they work equally well in a concurrent setting, which is
notoriously hard for interactive zero-knowledge protocols. However,
while for interactive zero-knowledge we ... more >>>

We construct a secure protocol for any multi-party functionality
that remains secure (under a relaxed definition of security) when
executed concurrently with multiple copies of itself and other
protocols. We stress that we do *not* use any assumptions on
existence of trusted parties, common reference string, honest
majority or synchronicity ... more >>>

Our main result implies the following easily formulated statement. The set of edges E of every finite bipartite graph can be split into poly(log |E|) subsets so the all the resulting bipartite graphcs are almost regular. The latter means that the ratio between the maximal and minimal non-zero degree of ... more >>>