Journal of Cryptology

, Volume 15, Issue 2, pp 75–96 | Cite as

Securing Threshold Cryptosystems against Chosen Ciphertext Attack

  • Victor Shoup
  • Rosario Gennaro


For the most compelling applications of threshold cryptosystems, security against chosen cipher text attack is a requirement. However, prior to the results presented here, there appeared to be no practical threshold cryptosystems in the literature that were provably chosen ciphertext secure, even in the idealized random oracle model. The contribution of this paper is to present two very practical threshold cryptosystems, and to prove that they are secure against chosen ciphertext attack in the random oracle model. Not only are these protocols computationally very efficient, but they are also non-interactive, which means they can be easily run over an asynchronous communication network.

Key words. Public key encryption, Threshold cryptography, Chosen ciphertext attack. 


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Copyright information

© International Association for Cryptologic Research 2002

Authors and Affiliations

  • Victor Shoup
    • 1
  • Rosario Gennaro
    • 2
  1. 1.IBM Zurich Research Lab, Saumerstrasse 4, CH-8803 Rueschlikon, Switzerland
  2. 2.IBM T. J. Watson Research Center, P.O.Box 704, Yorktown Heights, NY 10598, U.S.A.

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