New and improved constructions of non-malleable cryptographic protocols

We present a new constant round protocol for non-malleable zero-knowledge. Using this protocol as a subroutine, we obtain a new constant-round protocol for non-malleable commitments. Our constructions rely on the existence of (standard) collision resistant hash functions. Previous constructions either relied on the existence of trapdoor permutations and hash functions that are collision resistant against sub-exponential sized circuits, or required a super-constant number of rounds. Additional results are the first construction of a non-malleable commitment scheme that is statistically hiding (with respect to opening), and the first non-malleable commitments that satisfy a strict polynomial-time simulation requirement. Our approach differs from the approaches taken in previous works in that we view nonmalleable zero-knowledge as a building-block rather than an end goal. This gives rise to a modular construction of non-malleable commitments and results in a somewhat simpler analysis.

• Type: Conference
• Year: 2005
• Where: STOC
• Authors: Rafael Pass, Alon Rosen
• Keywords: Algorithms, Non-malleable Commitments, STOC 2005, Strict Polynomial-time Simulation, Sub-exponential Sized Circuits