Cryptology ePrint Archive: Report 2019/1367

Tight reduction for generic construction of certificateless signature and tightly-secure scheme without pairing

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 show that their construction can achieve tight security if the underlying signature scheme is existentially unforgeable under adaptive chosen-message attacks in the multi-user setting with adaptive corruptions. Moreover, we instantiate a tightly-secure certificateless signature scheme without pairing, whose security is independent of the number of users. Best of our knowledge, this scheme is the first tightly-secure certificateless signature scheme.

Category / Keywords: public-key cryptography / certificateless signatures, key escrow, tight security

Date: received 26 Nov 2019, last revised 27 Nov 2019

Contact author: hashimoto k au at m titech ac jp

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Version: 20191128:033840 (All versions of this report)

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