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Mathematical Problems in Engineering
Volume 2014 (2014), Article ID 728591, 16 pages
Research Article

Secure Certificateless Signature with Revocation in the Standard Model

Department of Mathematics, National Changhua University of Education, Chang-Hua City 500, Taiwan

Received 6 May 2014; Revised 3 September 2014; Accepted 3 October 2014; Published 19 November 2014

Academic Editor: Kwok-Wo Wong

Copyright © 2014 Tung-Tso Tsai et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


Certificateless public key cryptography is very attractive in solving the key escrow problem which is inherent in identity- (ID-) based public key cryptography. In the past, a large number of certificateless cryptographic schemes and protocols were presented, but a secure certificateless signature in the standard model (without random oracles) is still not accessible until now. To the best of our knowledge, all the previously proposed certificateless signature schemes were insecure under a considerably strong security model in the sense that they suffered from outsiders’ key replacement attacks or the attacks from the key generation center (KGC). In this paper, we propose a certificateless signature scheme without random oracles. Moreover, our scheme is secure under the strong security model and provides a public revocation mechanism, called revocable certificateless signature (RCLS). Under the standard computational Diffie-Hellman assumption, we formally demonstrate that our scheme possesses existential unforgeability against adaptive chosen-message attacks.