International Association for Cryptologic Research

International Association
for Cryptologic Research


Fully Adaptive Decentralized Multi-Authority ABE

Pratish Datta , NTT Research
Ilan Komargodski , Hebrew University and NTT Research
Brent Waters , UT Austin and NTT Research
DOI: 10.1007/978-3-031-30620-4_15 (login may be required)
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Presentation: Slides
Conference: EUROCRYPT 2023
Abstract: Decentralized multi-authority attribute-based encryption (MA-ABE) is a distributed generalization of standard (ciphertext-policy) attribute-based encryption where there is no trusted central authority: any party can become an authority and issue private keys, and there is no requirement for any global coordination other than the creation of an initial set of common reference parameters. We present the first multi-authority attribute-based encryption schemes that are provably fully-adaptively secure. Namely, our construction is secure against an attacker that may corrupt some of the authorities as well as perform key queries adaptively throughout the life-time of the system. Our main construction relies on a prime order bilinear group where the k-linear assumption holds as well as on a random oracle. Along the way, we present a conceptually simpler construction relying on a composite order bilinear group with standard subgroup decision assumptions as well as on a random oracle. Prior to this work, there was no construction that could resist adaptive corruptions of authorities, no matter the assumptions used. In fact, we point out that even standard complexity leveraging style arguments do not work in the multi-authority setting.
  title={Fully Adaptive Decentralized Multi-Authority ABE},
  author={Pratish Datta and Ilan Komargodski and Brent Waters},