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Tightly Secure Hierarchical Identity-Based Encryption

Langrehr, Roman; Pan, Jiaxin

We construct the first tightly secure hierarchical identity-based encryption (HIBE) scheme based on standard assumptions, which solves an open problem from Blazy, Kiltz, and Pan (CRYPTO 2014). At the core of our constructions is a novel randomization technique that enables us to randomize user secret keys for identities with flexible length.
The security reductions of previous HIBEs lose at least a factor of Q, which is the number of user secret key queries. Different to that, the security loss of our schemes is only dependent on the security parameter. Our schemes are adaptively secure based on the Matrix Diffie-Hellman assumption, which is a generalization of standard Diffie-Hellman assumptions such as k-Linear. We have two tightly secure constructions, one with constant ciphertext size, and the other with tighter security at the cost of linear ciphertext size. Among other things, our schemes imply the first tightly secure identity-based signature scheme by a variant of the Naor transformation.

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Verlagsausgabe §
DOI: 10.5445/IR/1000125417
Veröffentlicht am 28.10.2020
Cover der Publikation
Zugehörige Institution(en) am KIT Institut für Programmstrukturen und Datenorganisation (IPD)
Institut für Theoretische Informatik (ITI)
Publikationstyp Zeitschriftenaufsatz
Publikationsmonat/-jahr 10.2020
Sprache Englisch
Identifikator ISSN: 0933-2790, 1432-1378
KITopen-ID: 1000125417
Erschienen in Journal of cryptology
Band 33
Heft 4
Seiten 1787–1821
Vorab online veröffentlicht am 15.09.2020
Schlagwörter Hierarchical identity-based encryption, tight security, affine message authentication codes
Nachgewiesen in Scopus
Web of Science
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