Key Derivation for Squared-Friendly Applications: Lower Bounds

Security of a cryptographic application is typically defined by a security game. The adversary, within certain resources, cannot win with probability much better than 0 (for unpredictability applications, like one-way functions) or much better than 1 2 (indistinguishability applications for instance encryption schemes). In so called squared-friendly applications the winning probability of the adversary, for different values of the application secret randomness, is not only close to 0 or 1 2 on average, but also concentrated in the sense that it’s second central moment is small. The class of squared-friendly applications, which contains all unpredictability applications and many indistinguishability applications, is particularly important in the context of key derivation. Barak et al. observed that for square-friendly applications one can beat the “RT-bound”, extracting secure keys with significantly smaller entropy loss. In turn Dodis and Yu showed that in squaredfriendly app...

• Type: Journal
• Year: 2016
• Where: IACR
• Authors: Maciej Skorski
• Keywords: Biometrics, IACR 2016