Vulnerability Bounds and Leakage Resilience of Blinded Cryptography under Timing Attacks

Abstract

We establish formal bounds for the number of min-entropy bits that can be extracted in a timing attack against a cryptosystem that is protected by blinding, the state-of-the art countermeasure against timing attacks. Compared with existing bounds, our bounds are both tighter and of greater operational significance, in that they directly address the key’s one-guess vulnerability. Moreover, we show that any semantically secure public-key cryptosystem remains semantically secure in the presence of timing attacks, if the implementation is protected by blinding and bucketing. This result shows that, by considering (and justifying) more optimistic models of leakage than recent proposals for leakage-resilient cryptosystems, one can achieve provable resistance against side-channel attacks for standard cryptographic primitives.