Identity-based encryption with (almost) tight security in the multi-instance, multi-ciphertext setting

Dennis Hofheinz, Jessica Koch, Christoph Striecks

Publikation: Beitrag in FachzeitschriftArtikelBegutachtung


We construct an identity-based encryption (IBE) scheme that is tightly secure in a very strong sense. Specifically, we consider a setting with many instances of the scheme and many encryptions per instance. In this setting, we reduce the security of our scheme to a variant of a simple assumption used for a similar purpose by Chen and Wee (Crypto 2013). The security loss of our reduction is O(k) (where k is the security parameter). Our scheme is the first IBE scheme to achieve this strong flavor of tightness under a simple assumption. Technically, our scheme is a variation of the IBE scheme by Chen and Wee. However, in order to "lift" their results to the multi-instance, multi-ciphertext case, we need to develop new ideas. In particular, while we build on (and extend) their high-level proof strategy, we deviate significantly in the low-level proof steps.
Seiten (von - bis)799-822
FachzeitschriftJournal of Cryptology
PublikationsstatusVeröffentlicht - 29 Feb. 2024

Research Field

  • Cyber Security


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