An efficient attribute-based authenticated key exchange protocol

Abstract

In this paper, we present a new and efficient construction of an Attribute-Based Authenticated Key Exchange (ABAKE) protocol, providing fine-grained access control over data. The state-of-the-art constructions of ABAKE protocols rely on extensive pairing and exponentiation operations (both polynomial in the size of the access policies) over appropriate groups equipped with bilinear maps. Our new construction of ABAKE protocol reduces the number of pairing operations to be constant (to be precise only 7) and the number of exponentiations to be linear in the number of clauses in the disjunctive normal form representing the general access policies. The main workhorse of our ABAKE construction is an Attribute-Based Signcryption (ABSC) scheme with constant number of pairings (only 7), which we construct. This also gives the first construction of ABSC schemes with constant number of pairings for general purpose access policies in the standard model. Our ABAKE protocol is also round-optimal, i.e., it is a single round protocol consisting of only a single message flow among the parties involved, and is asynchronous in nature, i.e., the message sent by one party does not depend on the incoming message from the other party. The security of our ABAKE protocol is proved under a variant of the Bilinear Diffie-Hellman Exponent assumption, in the Attribute-Based extended Canetti-Krawzyck (ABeCK) model, which is an extension of the extended Canetti-Krawzyck (eCK) model for attribute-based framework.