Registered ABE via Predicate Encodings

This paper presents the first generic black-box construction of registered attribute-based encryption (Reg-ABE) via predicate encoding [TCC’14]. The generic scheme is based on k-Lin assumption in the prime-order bilinear group and implies the following concrete schemes that improve existing results: the first Reg-ABE scheme for span program in the prime-order group; prior work uses composite-order group;the first Reg-ABE scheme for zero inner-product predicate from k-Lin assumption; prior work relies on generic group model (GGM);the first Reg-ABE scheme for arithmetic branching program (ABP) which has not been achieved previously. Technically, we follow the blueprint of Hohenberger et al. [EUROCRYPT’23] but start from the prime-order dual-system ABE by Chen et al. [EUROCRYPT’15], which transforms a predicate encoding into an ABE. The proof follows the dual-system method in the context of Reg-ABE: we conceptually consider helper keys as secret keys; furthermore, malicious public keys are handled via pairing-based quasi-adaptive non-interactive zero-knowledge argument by Kiltz and Wee [EUROCRYPT’15].