Paper 2019/1219

Multi-Locking and Perfect Argument Order: Two Major Improvements of Attribute-Based Encryption~(Long Paper)

Nugier Cyrius, Adelin Remi, Migliore Vincent, and Alata Eric

Abstract

Attribute Based Encryption, proposed by Sahai and Waters in 2007, is a set of promising cryptographic schemes that enable various fine grained access control on encrypted data. With a unique encryption key, a user is able to encrypt data for a very specific group of recipient that matches a set of attributes contained inside their decryption key. In current scenario where personal devices share an increasing volume of private data on the web, such encryption algorithms are more than ever a strong alternative to standard encryption algorithms. In this paper, we propose two major improvements of ABE namely the Perfect Argument Order Optimization and the Multi-Locking. Multi-Locking ABE is an extension of ABE that enables to share access control policy on an arbitrary number of entities. We also make a step further for the speed-up of ABE by providing the ``Perfect Argument Order Optimization'', which is a generalization of the ``Fixed Argument Optimization'' of Scott et al. to a much wider range of ABE constructions (and in particular to our Multi-Locking ABE). Based on those two improvements we propose a construction of the first privacy-preserving Cloud service based on ABE, allowing ephemeral accesses to the data. The Multi-Locking ABE and the Perfect Argument Order Optimization have been successfully integrated to the OpenABE library, providing a speed-up for a variety of ABE constructions.