Chosen-Ciphertext Secure Fuzzy Identity-Based Key Encapsulation without ROM
We use hybrid encryption with Fuzzy Identity-Based Encryption (Fuzzy-IBE) schemes, and present the first and efficient fuzzy identity-based key encapsulation mechanism (Fuzzy-IB-KEM) schemes which are chosen-ciphertext secure (CCA) without random oracle in the selective-ID model. To achieve these goals, we consider Fuzzy-IBE schemes as consisting of separate key and data encapsulation mechanisms (KEM-DEM), and then give the definition of Fuzzy-IB-KEM. Our main idea is to enhance Sahai and Waters' "large universe" construction (Sahai and Waters, 2005), chosen-plaintext secure (CPA) Fuzzy-IBE, by adding some redundant information to the ciphertext to make it CCA-secure.
Formal Proof of Relative Strengths of Security between ECK2007 Model and other Proof Models for Key Agreement Protocols
In 2005, Choo, Boyd & Hitchcock compared four well-known indistinguishability-based proof models for key agreement protocols, which contains the Bellare & Rogaway (1993, 1995) model, the Bellare , Pointcheval & Rogaway 2000 model and the Canetti & Krawczyk (2001) model. After that, researchers from Microsoft presented a stronger security model, called Extended Canetti-Krawczyk model (2007). In this paper, we will point out the differences between the new proof model and the four previous models, and analyze the relative strengths of security of these models. To support the implication or non-implication relation between these models, we will provide proof or counter-example.
Full Security:Fuzzy Identity Based Encryption
At EUROCRYPT 2005, Sahai and Waters presented the Fuzzy Identity Based Encryption (Fuzzy-IBE) which could be used for biometrics and attribute-based encryption in the selective-identity model. When a secure Fuzzy-IBE scheme in the selective-identity model is transformed to full identity model it exist an exponential loss of security. In this paper, we use the CPA secure Gentry's IBE (exponent inversion IBE) to construct the first Fuzzy IBE that is fully secure without random oracles. In addition, the same technique is used to the modification of CCA secure Gentry's IBE which introduced by Kiltz and Vahlis to get the CCA secure Fuzzy IBE in the full-identity model.