Maciej Skorski

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The so-called leakage-chain rule is a very important tool used in many security proofs. It gives an upper bound on the entropy loss of a random variable X in case the adversary who having already learned some random variables Z1,. .. , Z ℓ correlated with X, obtains some further information Z ℓ+1 about X. Analogously to the information-theoretic case, one(More)
Hardcore lemmas are results in complexity theory which state that average-case hardness must have a very hard " kernel " , that is a subset of instances where the given problem is extremely hard. They find important applications in hardness amplification. In this paper we revisit the following two fundamental results: (a) The hardcore lemma for(More)
Hardcore lemmas are results in complexity theory which state that average-case hardness must have a very hard " kernel " , that is a subset of instances where the problem is extremely hard. Such results find important applications in hardness amplification. In this paper we revisit two classical results: (a) The hardcore lemma for unpredictability, proved(More)
Weak pseudorandom functions (wPRFs) found an important application as main building blocks for leakage-resilient ciphers (EURO-CRYPT'09). Several security bounds, based on different techniques, were given to these stream ciphers. The security loss in these reduction-based proofs is always polynomial, but has not been studied in detail. The aim of this paper(More)