IACR News item: 04 March 2015
Fabrice Benhamouda, Olivier Blazy, Céline Chevalier, David Pointcheval, Damien Vergnaud
ePrint ReportThis paper follows their path with, first, a new efficient instantiation of SPHF on Cramer-Shoup ciphertexts, which allows to get rid of the SSNIZK proof and leads to the design of the most efficient one-round PAKE known so far, in the BPR model, and in addition without pairings.
In the UC framework, the security proof required the simulator to be able to extract the hashing key of the SPHF, hence the additional SSNIZK proof. We improve the way the latter extractability is obtained by introducing the notion of trapdoor smooth projective hash functions (TSPHFs). Our concrete instantiation leads to the most efficient one-round PAKE UC-secure against static corruptions to date.
We additionally show how these SPHFs and TSPHFs can be used for blind signatures and zero-knowledge proofs with straight-line extractability.
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