Cryptology ePrint Archive: Report 2020/1331

Efficient mixing of arbitrary ballots with everlasting privacy: How to verifiably mix the PPATC scheme

Kristian Gjøsteen and Thomas Haines and Morten Rotvold Solberg

Abstract: The long term privacy of voting systems is of increasing concern as quantum computers come closer to reality. Everlasting privacy schemes offer the best way to manage these risks at present. While homomorphic tallying schemes with everlasting privacy are well developed, most national elections, using electronic voting, use mixnets. Currently the best candidate encryption scheme for making these kinds of elections everlastingly private is PPATC, but it has not been shown to work with any mixnet of comparable efficiency to the current ElGamal mixnets. In this work we give a paper proof, and a machine checked proof, that the variant of Wikstrom's mixnet commonly in use is safe for use with the PPATC encryption scheme.

Category / Keywords: cryptographic protocols / mix net, secure voting, machine checked

Original Publication (with minor differences): The 25th Nordic Conference on Secure IT Systems (Nordsec 2020)

Date: received 23 Oct 2020, last revised 23 Oct 2020

Contact author: thomas haines at ntnu no

Available format(s): PDF | BibTeX Citation

Version: 20201023:085353 (All versions of this report)

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