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Improved Broadcast Encryption Scheme with Constant-Size Ciphertext

Renaud Dubois 1 Aurore Guillevic 2, 1 Marine Sengelin Le Breton 1
2 CASCADE - Construction and Analysis of Systems for Confidentiality and Authenticity of Data and Entities
DI-ENS - Département d'informatique de l'École normale supérieure, Inria Paris-Rocquencourt, CNRS - Centre National de la Recherche Scientifique : UMR 8548
Abstract : The Boneh-Gentry-Waters (BGW) [3] broadcast encryption scheme is optimal regarding the overhead size. This performance relies on the use of a pairing. Hence this protocol can benefit from public key improvements. The main lasting constraint is the computation time at receiver end as it depends on the number of revoked users. In this paper we describe two modifications to improve BGW bandwidth and time complexity. First we rewrite the protocol with an asymmetric pairing over Barreto-Naehrig (BN) curves instead of a symmetric one over supersingular curves. This modification leads to a practical gain of 60% in speed and 84% in bandwidth. The second tweaks allows to reduce the computation time from O(n − r) to min (O(r),O(n − r)) for the worst case (and better for the average case). We give performance measures of our implementation for a 128-bit security level of the modified protocol on a smartphone.
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Submitted on : Friday, January 30, 2015 - 5:11:22 PM
Last modification on : Tuesday, May 4, 2021 - 2:06:02 PM

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Renaud Dubois, Aurore Guillevic, Marine Sengelin Le Breton. Improved Broadcast Encryption Scheme with Constant-Size Ciphertext. Pairing 2012 - 5th International Conference Pairing-Based Cryptography, May 2012, Cologne, Germany. pp.196-202, ⟨10.1007/978-3-642-36334-4_12⟩. ⟨hal-01111663⟩



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