Practical Leakage-Resilient Pseudorandom Objects with Minimum Public Randomness

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 amounts of public randomness to be proven leakage-resilient. In this paper, we show that tweaked designs with minimum randomness requirements can be proven leakageresilient in minicrypt. That is, either these constructions are secure, or we are able to construct public-key cryptographic primitives from symmetric-key building blocks and their leakage functions (which is very unlikely). Hence, our results improve the practical relevance of two important leakage-resilient pseudorandom objects.