Abstract. In this paper, we present an identity-based encryption (IBE) scheme from lattices with efficient key revocation. We adopt multiple trapdoors from the Agrawal-Boneh-Boyen and GentryPeikerty-Vaikuntanathan lattice IBE schemes to realize key revocation, which in turn, makes use of binary-tree data structure. Using our scheme, key update requires logarithmic complexity in the maximal number of users and linear in the number of revoked users for the relevant key authority. We prove that our scheme is selective secure in the standard model and under the LWE assumption, which is as hard as the worst-case approximating short vectors on arbitrary lattices. Moreover, our key revocation techniques from lattices can be applied to obtain revocable functional encryption schemes in the similar setting.
Abstract. In the context of public key cryptography, combined encryption and signature schemes have attractive properties and are sometimes used in practice. The topic of joint security of signature and encryption schemes has a fairly extensive history. In this paper, we focus on the combined public-key schemes in attribute-based setting. We present a security model for combined CP-ABE and ABS schemes in the joint security setting. An efficient concrete construction of CP-ABE and ABS based on Waters's CP-ABE scheme is proposed. Our scheme is proved to be selectively jointly secure in standard model under reasonable assumptions. Moreover, we consider the problem of how to build attribute-based signcryption (ABSC) and obtain an ABSC scheme and show that it is secure. We also give a general construction of combined ABSC, CP-ABE and ABS schemes from combined CP-ABE and ABS schemes.
Abstract. We consider semi-adaptive security for attribute-based encryption, where the adversary specifies the challenge attribute vector after it sees the public parameters but before it makes any secret key queries. We present two constructions of semi-adaptive attribute-based encryption under static assumptions with short ciphertexts. Previous constructions with short ciphertexts either achieve the weaker notion of selective security, or require parameterized assumptions.As an application, we obtain improved delegation schemes for Boolean formula with semi-adaptive soundness, where correctness of the computation is guaranteed even if the client's input is chosen adaptively depending on its public key. Previous delegation schemes for formula achieve one of adaptive soundness, constant communication complexity, or security under static assumptions; we show how to achieve semi-adaptive soundness and the last two simultaneously.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.