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 >>>

One of the central questions in Cryptography today is proving security of the protocols ``on the Internet'', i.e., in a concurrent setting where there are multiple interactions between players, and where the adversary can play so called ``man-in-the-middle'' attacks, forwarding and modifying messages between two or more unsuspecting players. Indeed, ... more >>>