Personal Identification Numbers (PINs) are commonly used as an authenti-cation mechanism. An important security requirement is that PINs should be hard to guess for an attacker. On the other hand, remembering several random PINs can be difficult task for an individual. We evaluate several dictionary-based methods of choosing a PIN. We experimentally show… (More)
We analyze recently proposed encryption algorithm Puzzle , aimed at efficient (real time) encryption of video streams. We show some weaknesses in the generation of components used for encryption. Moreover, we present a known plaintext attack on Puzzle. Some ideas on design of video encryption algorithms are discussed as well.
Oblivious transfer protocol is a basic building block of various cryptographic constructions. We propose a novel protocol – batch oblivious transfer. It allows efficient computation of multiple instances of oblivious transfer protocols. We apply this protocol to improve the fast simultaneous contract signing protocol, recently proposed in , which gains… (More)