Confidential Signatures and Deterministic Signcryption

  • Alexander W. Dent
  • Marc Fischlin
  • Mark Manulis
  • Martijn Stam
  • Dominique Schröder
Conference paper

DOI: 10.1007/978-3-642-13013-7_27

Part of the Lecture Notes in Computer Science book series (LNCS, volume 6056)
Cite this paper as:
Dent A.W., Fischlin M., Manulis M., Stam M., Schröder D. (2010) Confidential Signatures and Deterministic Signcryption. In: Nguyen P.Q., Pointcheval D. (eds) Public Key Cryptography – PKC 2010. PKC 2010. Lecture Notes in Computer Science, vol 6056. Springer, Berlin, Heidelberg

Abstract

Encrypt-and-sign, where one encrypts and signs a message in parallel, is usually not recommended for confidential message transmission as the signature may leak information about the message. This motivates our investigation of confidential signature schemes, which hide all information about (high-entropy) input messages. In this work we provide a formal treatment of confidentiality for such schemes. We give constructions meeting our notions, both in the random oracle model and the standard model. As part of this we show that full domain hash signatures achieve a weaker level of confidentiality than Fiat-Shamir signatures. We then examine the connection of confidential signatures to signcryption schemes. We give formal security models for deterministic signcryption schemes for high-entropy and low-entropy messages, and prove encrypt-and-sign to be secure for confidential signature schemes and high-entropy messages. Finally, we show that one can derandomize any signcryption scheme in our model and obtain a secure deterministic scheme.

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Copyright information

© Springer-Verlag Berlin Heidelberg 2010

Authors and Affiliations

  • Alexander W. Dent
    • 1
  • Marc Fischlin
    • 2
  • Mark Manulis
    • 2
  • Martijn Stam
    • 3
  • Dominique Schröder
    • 2
  1. 1.Royal HollowayUniversity of LondonU.K.
  2. 2.Darmstadt University of TechnologyGermany
  3. 3.LACAL, EPFLSwitzerland

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