Here we show two ways to construct hash functions from $\psi$ which are indifferentiable from a random oracle. Because $\psi$ is relatively simple, our analyses are also simple. One of our constructions uses a novel ``wallpapering'' approach, whereas the other uses the hash-twice-and-add approach of Brier et al.
Category / Keywords: public-key cryptography / Indifferentiability, hashing to elliptic curves, Elligator Date: received 2 Dec 2020, last revised 2 Dec 2020 Contact author: mike at shiftleft org Available format(s): PDF | BibTeX Citation Note: I wrote this paper 2013, but I'm posting it in 2020 because it's relevant to the CFRG hash-to-curve discussion. Version: 20201202:150737 (All versions of this report) Short URL: ia.cr/2020/1513