Hierarchical Identity Based Encryption with Polynomially Many Levels
- Craig GentryAffiliated withStanford & IBM
- , Shai HaleviAffiliated withIBM
We present the first hierarchical identity based encryption (HIBE) system that has full security for more than a constant number of levels. In all prior HIBE systems in the literature, the security reductions suffered from exponential degradation in the depth of the hierarchy, so these systems were only proven fully secure for identity hierarchies of constant depth. (For deep hierarchies, previous work could only prove the weaker notion of selective-ID security.) In contrast, we offer a tight proof of security, regardless of the number of levels; hence our system is secure for polynomially many levels.
Our result can very roughly be viewed as an application of Boyen’s framework for constructing HIBE systems from exponent-inversion IBE systems to a (dramatically souped-up) version of Gentry’s IBE system, which has a tight reduction. In more detail, we first describe a generic transformation from “identity based broadcast encryption with key randomization” (KR-IBBE) to a HIBE, and then construct KR-IBBE by modifying a recent construction of IBBE of Gentry and Waters, which is itself an extension of Gentry’s IBE system. Our hardness assumption is similar to that underlying Gentry’s IBE system.
- Hierarchical Identity Based Encryption with Polynomially Many Levels
- Book Title
- Theory of Cryptography
- Book Subtitle
- 6th Theory of Cryptography Conference, TCC 2009, San Francisco, CA, USA, March 15-17, 2009. Proceedings
- pp 437-456
- Print ISBN
- Online ISBN
- Series Title
- Lecture Notes in Computer Science
- Series Volume
- Series ISSN
- Springer Berlin Heidelberg
- Copyright Holder
- Springer-Verlag Berlin Heidelberg
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