Cryptology ePrint Archive: Report 2006/207

The Kurosawa-Desmedt Key Encapsulation is not Chosen-Ciphertext Secure

Javier Herranz and Dennis Hofheinz and Eike Kiltz

Abstract: At CRYPTO 2004, Kurosawa and Desmedt presented a hybrid public-key encryption scheme that is chosen-ciphertext secure in the standard model. Until now it was unknown if the key-encapsulation part of the Kurosawa-Desmedt scheme by itself is still chosen-ciphertext secure or not. In this short note we answer this question to the negative, namely we present a simple chosen-ciphertext attack on the Kurosawa-Desmedt key encapsulation mechanism.

Category / Keywords: public-key cryptography / Chosen-ciphertext attack, key encapsulation mechanism

Date: received 21 Jun 2006, last revised 13 Sep 2006

Contact author: kiltz at cwi nl

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Version: 20060913:080117 (All versions of this report)

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