Why Zero-Knowledge protocols are used for NP problems if IP is the class of interactive proof systems where they come from?
Why the differential cryptanalysis complexity is linear with inverse of the probability while linear cryptanalysis is quadratic with the bias inverse?
Let $X$ be the set of 256-bit strings and $x \rightarrow H(x)$ a map on this set, where $H$ is SHA-256. How often is $H^-1(y)$ empty?
How to estimate the maximum computational cost bound for Key Derivation Functions (KDFs) before it becomes useless security-wise?
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