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2010

A New and Improved Paradigm for Hybrid Encryption Secure Against Chosen-Ciphertext Attack

9 years 5 months ago
A New and Improved Paradigm for Hybrid Encryption Secure Against Chosen-Ciphertext Attack
We present a new encryption scheme which is secure against adaptive chosenciphertext attack (or CCA2-secure) in the standard model (i.e. without the use of random oracle). Our scheme is a hybrid one: it first uses a public-key step (the Key Encapsulation Module or KEM) to encrypt a random key, which is then used to encrypt the actual message using a symmetric encryption algorithm (the Data Encapsulation Module or DEM). Our scheme is a modification of the hybrid scheme presented by Shoup in [18] (based on the Cramer-Shoup scheme in [4]). Its major practical advantage is that it saves the computation of one exponentiation and produces shorter ciphertexts. This effciency improvement is the result of a surprising observation: previous hybrid schemes were proven secure by proving that both the KEM and the DEM were CCA2secure. On the other hand, our KEM is not CCA2-secure, yet the whole scheme is, assuming the Decisional Diffie-Hellman (DDH) Assumption. Finally we generalize our new sche...
Yvo Desmedt, Rosario Gennaro, Kaoru Kurosawa, Vict
Added 28 Jan 2011
Updated 28 Jan 2011
Type Journal
Year 2010
Where JOC
Authors Yvo Desmedt, Rosario Gennaro, Kaoru Kurosawa, Victor Shoup
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