We give a simple structure-mirroring PKE-to-IBE transformation via indistinguisha- bility obfuscation and puncturable PRFs. This transformation establishes a connec- tion between PKE and IBE in general. Particularly, it provides a liberal interface for transferring the KDM security results (both positive and negative) from PKE to IBE, though in the selective-identity sense.
On the positive side, we present two constructions that achieve KDM security in the adaptive-identity sense for the first time. One is generically built from identity-based hash proof system (IB-HPS) with homomorphic property, which indicates that the IBE schemes of Gentry (Eurocrypt 2006), Coron (DCC 2009), Chow et al. (CCS 2010) are actually KDM-secure in the single-key setting. The other is built from indistinguishability obfuscation and a new notion named puncturable unique signature, which is bounded KDM-secure in the single-key setting.
On the negative side, we separate n-circular security (which is a prototypical case of KDM security) from the standard IND-CPA/CCA security for IBE by giving a coun- terexample based on differing-inputs obfuscation and a new notion named puncturable IBE.Category / Keywords: public-key cryptography / KDM security, IBE, IB-HPS, Obfuscation, Counterexample Date: received 26 Oct 2016, last revised 9 Feb 2017 Contact author: yuchen prc at gmail com; jiangzhang09@gmail com Available format(s): PDF | BibTeX Citation Note: We revised the security result of KDM-secure IBE from homomorphic IB-HPS. Version: 20170210:031137 (All versions of this report) Short URL: ia.cr/2016/1020 Discussion forum: Show discussion | Start new discussion