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.
|Original language||American English|
|Title of host publication||Advances in Cryptology – EUROCRYPT 2023 - 42nd Annual International Conference on the Theory and Applications of Cryptographic Techniques, 2023, Proceedings|
|Editors||Carmit Hazay, Martijn Stam|
|Publisher||Springer Science and Business Media Deutschland GmbH|
|Number of pages||32|
|State||Published - 2023|
|Event||42nd Annual International Conference on Theory and Applications of Cryptographic Techniques, EUROCRYPT 2023 - Lyon, France|
Duration: 23 Apr 2023 → 27 Apr 2023
|Name||Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics)|
|Conference||42nd Annual International Conference on Theory and Applications of Cryptographic Techniques, EUROCRYPT 2023|
|Period||23/04/23 → 27/04/23|
Bibliographical notePublisher Copyright:
© 2023, International Association for Cryptologic Research.