CERTIFICATELESS PROXY SIGNATURE SCHEME

A new paradigm of certificateless public key cryptography was introduced by Al-Riyami and Paterson to eliminate both the use of certificates in certified public key cryptography and the key-escrow problem in identity based cryptography. They also proposed a certificateless signature (CLS) scheme, which was later found to be vulnerable to proxy signature forgery. Recently, Li et al. proposed a new CLS and certificateless proxy signature (CLPS) schemes. In this paper, we show Li et al.'s CLPS scheme is not secure against signature forgery attack, and present new CLS and CLPS schemes.