Hierarchical Identity Based Encryption with Polynomially Many Levels

9 years 11 months ago
Hierarchical Identity Based Encryption with Polynomially Many Levels
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) t...
Craig Gentry, Shai Halevi
Added 25 Nov 2009
Updated 25 Nov 2009
Type Conference
Year 2009
Where TCC
Authors Craig Gentry, Shai Halevi
Comments (0)