Public-key cryptosystems based on composite degree residuosity classes

Abstract

This paper investigates a novel computational problem, na- mely the Composite Residuosity Class Problem, and its applications to public-key cryptography. We propose a new trapdoor mechanism and derive from this technique three encryption schemes: a trapdoor permu- tation and two homomorphic probabilistic encryption schemes computa- tionally comparable to RSA. Our cryptosystems, based on usual modular arithmetics, are provably secure under appropriate assumptions in the standard model.