Paper 2014/465 Original: eprint.iacr.org/2014/465 ↗

Semi-Adaptive Attribute-Based Encryption and Improved Delegation for Boolean Formula

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.