Practical constructions and new proof methods for large universe attribute-based encryption

Abstract

We propose two large universe Attribute-Based Encryption constructions. In a large universe ABE system any string can be used as an attribute and attributes need not be enumerated at system setup. Our first construction establishes a novel large universe Ciphertext-Policy ABE scheme on prime order bilinear groups, while the second achieves a significant efficiency improvement over the large universe Key-Policy ABE system of Lewko-Waters and Lewko. Both schemes are selectively secure in the standard model under two "q-type" assumptions similar to ones used in prior works. Our work brings back "program and cancel" techniques to this problem and aims in providing practical large universe ABE implementations.To showcase the efficiency improvements over prior constructions, we provide implementations and benchmarks of our schemes in Charm; a programming environment for rapid prototyping of cryptographic primitives. We compare them to implementations of the only three published constructions that offer unbounded ABE in the standard model.

Efficient Statically-Secure Large-Universe Multi-Authority Attribute-Based Encryption

“…Although incomparable to both of them, it contains fewer terms, hence it is relatively weaker. This comes in contrast to the fact that our multi-authority construction supports more features than the two ABE schemes of [40]. The reason of the apparent paradox is the use of the static security and random oracle model in this work versus selective security and standard model in [40].…”

“…The assumption is closely related to the two assumptions presented in [40]. Although incomparable to both of them, it contains fewer terms, hence it is relatively weaker.…”

“…The first large universe KP-ABE construction in the standard model was given in [28] (composite order groups). Two large universe constructions in prime order groups were presented in [40] and both techniques, layering and individual randomness, from that paper are extended and utilized in our current cosntruction. Okamoto and Takashima initiated the dual pairing vector space framework in various works [34,35,36], which lead to the first large universe KP-ABE construction in prime order group groups by Lewko [25].…”

“…Each piece corresponds to a different authority, while in the single authority setting private key requests are naturally atomic. We extend the existing "program and cancel" techniques from two large universe constructions presented in [40] in order to adapt to the multiauthority setting and introduce two new ones. The trade-offs for our performance improvements are the use of the static model and an assumption whose size depends on the complexity of the challenge ciphertext policy.…”

Face Search in Encrypted Domain

“…One of straightforward ways of securing digital image transmission is to encrypt the images [23][11] [29]. In image encryption, traditional methods like those of asymmetric encryption in public key systems [6] are often adopted, other methods including image scrambling using Hilberts Space-filling Curves (HSC) [17] as well as image sharing based on Chinese Remainder Theorem (CRT) [26] and Visual Cryptography(VC) [20], etc.…”