Cryptology ePrint Archive: Report 2003/024

On Modeling IND-CCA Security in Cryptographic Protocols

Dennis Hofheinz and Joern Mueller-Quade and Rainer Steinwandt

Abstract: Two common notions of security for public key encryption schemes are shown to be equivalent: we prove that indistinguishability against chosen-ciphertext attacks (IND-CCA) is in fact polynomially equivalent to (yet "slightly" weaker than) securely realizing the ideal functionality F_PKE in the general modeling of cryptographic protocols of [http://eprint.iacr.org/2000/067]. This disproves in particular the claim that security in the sense of IND-CCA strictly implies security in the sense of realizing F_PKE (see [http://eprint.iacr.org/2000/067]). Moreover, we give concrete reductions among such security notions and show that these relations hold for both uniform and non-uniform adversarial entities.

Category / Keywords: cryptographic protocols / formal cryptography, cryptographic protocols, probabilistic encryption

Date: received 5 Feb 2003

Contact author: hofheinz at ira uka de

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Version: 20030205:203202 (All versions of this report)

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