Journal of Cryptology

, Volume 20, Issue 2, pp 203–235 | Cite as

Formal Proofs for the Security of Signcryption



Signcryption is an asymmetric cryptographic method that provides simultaneously both message confidentiality and unforgeability at a low computational and communication overhead. In this paper we propose realistic security models for signcryption, which give the attacker power to choose both messages/signcryptexts as well as recipient/sender public keys when accessing the signcryption/unsigncryption oracles of attacked entities. We then show that Zheng's original signcryption scheme is secure in our confidentiality model relative to the Gap Diffie-Hellman problem and is secure in our unforgeability model relative to a Gap version of the discrete logarithm problem. All these results are shown in the random oracle model.


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Copyright information

© International Association for Cryptologic Research 2007

Authors and Affiliations

  1. 1.Institute for Infocomm Research, 21 Heng Mui Keng TerraceSingapore 119613Singapore
  2. 2.Department of Computing, Macquarie UniversityNorth Ryde, NSW 2109Australia
  3. 3.Department of Software and Information Systems, University of North Carolina at CharlotteCharlotte, NC 28223USA

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