Chinese Journal of Computers   Full Text
Title	An Efficient and Provably Secure Identity-Based Signature Scheme in the Standard Model
Authors	LI Ji-Guo JIANG Ping-Jin
Address	(College of Computer & Information Engineering, Hohai University, Nanjing 210098)
Year	2009
Issue	No.11(2130—2136)
Abstract &   Background	Abstract Compared with the traditional public key cryptosystem, identity-based cryptosystem can simplify the key management procedure from the view point of the efficiency and convenience. Most of identity-based signature schemes are secure in the random oracle model, but for which any implementation of the random oracle results in insecure schemes. For example, when random oracle is instantiated with concrete hash functions, the resulting scheme is nonrandom which may not be secure. This paper proposes an efficient and provably secure identity-based signature scheme. The scheme is existentially unforgeable against adaptive chosen message attacks under the computational Diffie-Hellman assumption in the standard model. Compared with the known identity-based scheme secure in the standard model, the scheme enjoys shorter signature length and less operation. Keywords identity-based signature; bilinear pairings; standard model; CDH-problem; chosen message attack Background This research is supported by the National Natural Science Foundation of China under grant No.60673070, the National High Technology Research and Development Program (863 Program) of China under grant No.2007AA01Z409, the Project of Jiangsu Province Police Ministry under grant No.200503002, and Program for New Century Excellent Talents in Hohai University. The concept of Identity-Based Cryptography (IBC) was proposed by Shamir in 1984. In an IBC system, the master secret is generated by a trusted authority, which we call the Private Key Generator (PKG), and the key generation mechanism is called an identity-based key extraction algorithm. Shamir’s original motivation for identity-based encryption was to simplify certificate management in e-mail systems. Nowadays, identity-based signature (IBS) has been discussed in the application of securing IPv6 neighbor and router discovery. However, improving the efficiency of IBS scheme is still an interesting research topic, which is one of the authors’ motivations. Another motivation of our research is to find an efficient and provably secure identity-based signature in the standard model (without random oracle model). Towards this goal, several recent results construct IBE systems secure without random oracles in weaker versions of the Boneh-Franklin model. However, building a fully secure IBE remained open problem three years ago. In Eurocrypt’2005, Waters presented the first efficient IBE scheme that was fully secure without random oracles and reduced the security of his scheme to the decisional bilinear Diffie-Hellman (BDH) problem, which solved the open problem proposed by Boneh and Boyen. Additionally, he showed that his techniques can be used to build a new signature scheme that is secure under the computational Diffie-Hellman assumption without random oracles. The only known construction of identity-based signatures that can be proven secure in the standard model is based on the approach of attaching certificates to non-identity-based signatures. This folklore construction method leads to schemes that are somewhat inefficient and leaves open the problem of finding more efficient direct constructions. Paterson and Schuldt presented an efficient identity-based signatures secure in the standard model in 2006. Based on Waters’ techniques, the authors propose an efficient identity-based signature scheme in the paper. The scheme is existentially unforgeable against adaptive chosen message attacks under the computational Diffie-Hellman assumption in the standard model. Compared with the known identity-based scheme secure in the standard model, the proposed scheme enjoys shorter signature length and less operation.