Cryptology ePrint Archive: Report 2020/1138

Epochal Signatures for Deniable Group Chats

Andreas Hülsing and Florian Weber

Abstract: We introduce formal definitions for deniability in group chats by extending a pre-existing model that did not have this property. We then introduce “epochal signatures” as an almost drop-in replacement for signatures, which can be used to make certain undeniable group-chats deniable by just performing that replacement. Following that we provide a practical epochal signature scheme and prove its security.

Category / Keywords: cryptographic protocols / Deniability, Signature, Epochal Signature, Group Chat

Original Publication (with minor differences): IEEE S&P 2021

Date: received 18 Sep 2020, last revised 3 Feb 2021

Contact author: mail at florianjw de, andreas at huelsing net

Available format(s): PDF | BibTeX Citation

Version: 20210203:120018 (All versions of this report)

Short URL: ia.cr/2020/1138