Cryptology ePrint Archive: Report 2004/194
A Note on An Encryption Scheme of Kurosawa and Desmedt
Rosario Gennaro and Victor Shoup
Abstract: Recently Kurosawa and Desmedt
presented a new hybrid encryption scheme which
is secure against adaptive chosen-ciphertext attack. Their scheme is a
modification of the Cramer-Shoup encryption scheme. Its major advantage with
respect to Cramer-Shoup is that it saves the computation of one exponentiation
and produces shorter ciphertexts.
However, the proof presented by Kurosawa and Desmedt relies on the use of
information-theoretic key derivation and message authentication functions.
In this note we present a different proof of security
which shows that the Kurosawa-Desmedt
scheme can be instantiated with any computationally secure
key derivation and message authentication functions, thus extending
the applicability of their paradigm, and improving its efficiency.
Category / Keywords: public-key cryptography / public-key encryption, chosen ciphertext security
Date: received 10 Aug 2004, last revised 18 May 2005
Contact author: shoup at cs nyu edu
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Version: 20050518:203445 (All versions of this report)
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