Paper 2017/650

Efficient Public Trace and Revoke from Standard Assumptions

Shweta Agrawal and Sanjay Bhattacherjee and Duong Hieu Phan and Damien Stehle and Shota Yamada

Abstract

We provide efficient constructions for trace-and-revoke systems with public traceability in the black-box confirmation model. Our constructions achieve adaptive security, are based on standard assumptions and achieve significant efficiency gains compared to previous constructions. Our constructions rely on a generic transformation from inner product functional encryption (IPFE) schemes to trace-and-revoke systems. Our transformation requires the underlying IPFE scheme to only satisfy a very weak notion of security -- the attacker may only request a bounded number of random keys -- in contrast to the standard notion of security where she may request an unbounded number of arbitrarily chosen keys. We exploit the much weaker security model to provide a new construction for bounded collusion and random key IPFE from the learning with errors assumption (LWE), which enjoys improved efficiency compared to the scheme of Agrawal et al. [CRYPTO'16]. Together with IPFE schemes from Agrawal et al., we obtain trace and revoke from LWE, Decision Diffie Hellman and Decision Quadratic Residuosity.