Distributed Broadcast Encryption from Bilinear Groups
Dimitris Kolonelos
Video
Abstract:
Distributed broadcast encryption (DBE) improves on the traditional notion of broadcast encryption by eliminating the key-escrow problem: In a DBE system, users generate their own secret keys non-interactively without the help of a trusted party. Then anyone can broadcast a message for a subset S of the users, in such a way that the resulting ciphertext size is sublinear in (and, ideally, independent of) |S|.
Wu et al. [Wu, Qin, Zhang and Domingo-Ferrer - CCS 2010] presented the first construction of DBE from bilinear pairings, however without a formal security proof and with public parameters of cubic size. Boneh and Zhandry [Boneh and Zhandry - CRYPTO 2014] showed a construction of DBE, which requires heavy cryptographic machinery, such as general-purpose indistinguishability obfuscation.
In this work, we present two practical DBE schemes from standard assumptions in prime-order bilinear groups. Our constructions are conceptually simple, satisfy the strong notion of adaptive security, and are concretely efficient. In fact, their performance, in terms of number of group elements and efficiency of the algorithms, is comparable with that of traditional (non-distributed) broadcast encryption schemes from bilinear groups.
Bio:
Dimitris Kolonelos is a PhD student at IMDEA Software Institute working in Cryptography, advised by Dario Fiore. Currently, he is a visiting scholar at UC Berkeley, hosted by Sanjam Garg. His research interests include succinct cryptographic primitives such as (Zero-Knowledge) Proof Systems and more broadly Public-Key Cryptographic primitives with advanced functionalities.