3 research outputs found
On Hardening Leakage Resilience of Random Extractors for Instantiations of Leakage Resilient Cryptographic Primitives
Random extractors are proven to be important building blocks in constructing leakage resilient cryptographic primitives.
Nevertheless, recent efforts showed that they are likely more leaky than other elementary
components (e.g. block ciphers) in unprotected implementations of these primitives, in the context of side-channel attacks. In this context, from the
adversary\u27s point of view, the extractors themselves could become the point of interest. This paper extends the
problem of how leakage resilience of random extractors could be to the case of protected instantiations.
Specifically, we investigate the feasibility of applying classical countermeasures to ameliorate leakage
resilience of cryptographic components and/or primitives against side-channel attacks, and then show how to
evaluate the physical leakage resilience of these instantiations theoretically and practically. The
countermeasures we consider are masking, shuffling, and combination of them. Taking one leakage-resilient
stream cipher presented at FOCS 2008 as a case of study, we not only examine the leakage resilience of the
underlying extractor, but also discuss how leakages from the extractor and from the underlying pseudo-random
generator respectively impact the leakage resilience of the stream cipher as a whole. On the
one hand, our theoretical and experimental results, which are consistent with each other, do justify some
existing observations. On the other hand, and more importantly, our results reveal some new observations that
contrast with these knowing ones, which explicitly indicates that previous observations are (mostly likely)
incomplete. We argue that our work is of both obvious theoretical interest and important practical significance,
and may help foster the further research on the design and implementation of random extractors in
leakage-resilient cryptography