Paper 2019/1367

Tight reduction for generic construction of certificateless signature and its instantiation from DDH assumption

Keitaro Hashimoto and Wakaha Ogata and Toi Tomita

Abstract

Certificateless signature was proposed by Al-Riyami and Paterson to eliminate the certificate management in the public-key infrastructures and solve the key escrow problem in the identity-based signature. In 2007, Hu et al. proposed a generic construction of certificateless signature. They construct certificateless signature scheme from any standard identity-based signature and signature scheme.However, their security reduction is loose; the security of the constructed scheme depends on the number of users. In this paper, we give the tight reduction for their construction and instantiate a tightly-secure certificateless signature scheme without pairing from DDH assumption. Best of our knowledge, this scheme is the first tightly-secure certificateless signature scheme.