JoWUA

Abstract

Blind signatures have key role in real world applications like e-cash, e-voting etc. The first blind signature was proposed by Chaum under public key infrastructure(PKI) model. The inherent problem in PKI is the certificate management which is overcome by identity(ID) based system. The ID based system is susceptible to key escrow problem. By removing the inherent problems of both PKI and ID based cryptosystems, Al Riyami et al. proposed a new cryptosystem called certificateless cryptosystem. Certificateless blind signature overcomes inherent key escrow problem in identity based blind signatures and does not require expensive certificates as in the public key infrastructure. Even though different certificateless blind signatures are proposed in the literature, rigorous formal proof is absent for all the proposals. Therefore in this paper we propose a new efficient provably secure certificateless blind signature scheme whose security can be proven to be equivalent to solving computational Diffie-Hellman (CDH) and chosen-target CDH problem in the random oracle model. As per our knowledge, our scheme is the only certificateless blind signature scheme which is proven to be strongly unforgeable and satisfies blindness property.