Cryptology ePrint Archive: Report 2019/981

Traceback for End-to-End Encrypted Messaging

Nirvan Tyagi and Ian Miers and Thomas Ristenpart

Abstract: Messaging systems are used to spread misinformation and other malicious content, often with dire consequences. End-to-end encryption improves privacy but hinders content-based moderation and, in particular, obfuscates the original source of malicious content. We introduce the idea of message traceback, a new cryptographic approach that enables platforms to simultaneously provide end-to-end encryption while also being able to track down the source of malicious content reported by users. We formalize functionality and security goals for message traceback, and detail two constructions that allow revealing a chain of forwarded messages (path traceback) or the entire forwarding tree (tree traceback). We implement and evaluate prototypes of our traceback schemes to highlight their practicality, and provide a discussion of deployment considerations.

Category / Keywords: applications / end-to-end encrypted messaging, anonymity, tracing, abuse reporting, message franking

Original Publication (with minor differences): CCS 2019

Date: received 27 Aug 2019

Contact author: nirvan tyagi at gmail com

Available format(s): PDF | BibTeX Citation

Version: 20190829:111524 (All versions of this report)

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