We construct a stream-cipher S whose implementation is secure even if arbitrary (adversely chosen) information on the internal state of S is leaked during computation. This captures all possible side-channel attacks on S where the amount of information leaked in a given period is bounded, but overall can be arbitrary large, in particular much larger than the internal state of S. The only other ...

Bent and resilient functions play significant roles in cryptography, coding theory, and combinatorics. However, the numbers of bent and resilient functions on a given number of variables are not known. Even a reasonable bound on the number of bent functions is not known and the best known bound on the number of resilient functions seems weak for functions of high orders. In this paper we presen...

We describe a broadcast encryption system with revocation, where security is based on PUF (Physical Unclonable Function) instead of a cryptographic problem. Our scheme is immune to advances of cryptography (which may suddenly ruin any system depending solely of cryptographic assumptions). It is resilient to collusion attacks, which are frequently the Achilles’ heel of schemes based on cryptogra...

Leakage resilience and black-box impossibility results in cryptography Ali Juma Doctor of Philosophy Graduate Department of Computer Science University of Toronto 2011 In this thesis, we present constructions of leakage-resilient cryptographic primitives, and we give black-box impossibility results for certain classes of constructions of pseudo-random

One of the main challenges in leakage-resilient cryptography is to obtain proofs of security against side-channel attacks, under realistic assumptions and for efficient constructions. In a recent work from CHES 2012, Faust et al. proposed new designs of stream ciphers and pseudorandom functions for this purpose. Yet, a remaining limitation of these constructions is that they require large amoun...

A Boolean function on n variables is q-resilient if for any subset of at most q variables, the function is very likely to be determined by a uniformly random assignment to the remaining n − q variables; in other words, no coalition of at most q variables has significant influence on the function. Resilient functions have been extensively studied with a variety of applications in cryptography, d...

The well known Decisional Diffie-Hellman assumption states that given g, g and g, for random a, b, the element g is pseudo-random. Canetti in [Can97] introduced a variant of this assumption in which b is still random but a is drawn according to some well-spread distribution. In this paper we prove that his assumption holds in the generic group model and demonstrate its broad applicability in th...

The enumeration of m-resilient Boolean functions in n variables would be a quite useful information for cryptography. But it seems to be an intractable open problem. Upper and lower bounds have appeared in the literature in the mid 80s. Since then, improving them has been the goal of several papers. In this paper, we give a new upper bound which partially improves upon all the known bounds.

Revelations over the past couple of years highlight the importance of understanding malicious and surreptitious weakening of cryptographic systems. We provide an overview of this domain, using a number of historical examples to drive development of a weaknesses taxonomy. This allows comparing different approaches to sabotage. We categorize a broader set of potential avenues for weakening system...