Predicate encryption against master-key tampering attacks

Abstract

Many real world attacks often target the implementation of a cryptographic scheme, rather than the algorithm itself, and a system designer has to consider new models that can capture these attacks. For example, if the key can be tampered by physical attacks on the device, the security of the scheme becomes totally unclear. In this work, we investigate predicate encryption (PE), a powerful encryption primitive, in the setting of tampering attacks. First, we show that many existing frameworks to construct PE are vulnerable to tampering attacks. Then we present a new security notion to capture such attacks. Finally, we take Attrapadung's framework in Eurocrypt'14 as an example to show how to "compile" these frameworks to tampering resilient ones. Moreover, our method is compatible with the original pair encoding schemes without introducing any redundancy.