We give an instantiation of Delay Encryption by modifying Boneh and Frankiln's IBE scheme, where we replace the master secret key by a long chain of isogenies, as in the isogeny VDF of De Feo, Masson, Petit and Sanso. Similarly to the isogeny-based VDF, our Delay Encryption requires a trusted setup before parameters can be safely used; our trusted setup is identical to that of the VDF, thus the same parameters can be generated once and shared for many executions of both protocols, with possibly different delay parameters.
We also discuss several topics around delay protocols based on isogenies that were left untreated by De Feo et al., namely: distributed trusted setup, watermarking, and implementation issues.
Category / Keywords: cryptographic protocols / time-lock puzzles, verifiable delay functions, isogenies Original Publication (in the same form): IACR-EUROCRYPT-2021 Date: received 28 May 2020, last revised 1 Mar 2021 Contact author: eurocrypt21 at defeo lu, burdges@gnunet org Available format(s): PDF | BibTeX Citation Version: 20210301:181602 (All versions of this report) Short URL: ia.cr/2020/638