Cryptanalysis and Further Improvement of a Certificateless Aggregate Signature Scheme

Abstract

Certificateless aggregate signature reduces nsignatures on n distinct messages from n distinct users into a compact single length signature. Recently Deng et al proposed CLAS Scheme which is an improvement of Hou et al scheme and claims that their scheme is secure against type I type II adversary but unfortunately it is found insecure by against the"Honest but Curious" attack by adversary II. In this paper, we demonstrate that Deng et al proposed CLAS scheme is insecure against type II adversary and suggest an improved CLAS scheme.