Paper 2021/1022

Zero-Knowledge Middleboxes

Paul Grubbs, Arasu Arun, Ye Zhang, Joseph Bonneau, and Michael Walfish

Abstract

This paper initiates research on zero-knowledge middleboxes (ZKMBs). A ZKMB is a network middlebox that enforces network usage policies on encrypted traffic. Clients send the middlebox zero-knowledge proofs that their traffic is policy-compliant; these proofs reveal nothing about the client’s communication except that it complies with the policy. We show how to make ZKMBs work with unmodified encrypted-communication protocols (specifically TLS 1.3), making ZKMBs invisible to servers. As a contribution of independent interest, we design optimized zero-knowledge proofs for TLS 1.3 session keys. We apply the ZKMB paradigm to several case studies. Experimental results suggest that in certain settings, performance is in striking distance of practicality; an example is a middlebox that filters domain queries (each query requiring a separate proof) when the client has a long-lived TLS connection with a DNS resolver. In such configurations, the middlebox’s overhead is 2–5 ms of running time per proof, and client latency to create a proof is several seconds. On the other hand, clients may have to store hundreds of MBs depending on the underlying zero-knowledge proof machinery, and for some applications, latency is tens of seconds.

Note: Added artifact evaluation badges and artifact appendix

Metadata
Available format(s)
PDF
Category
Applications
Publication info
Published elsewhere. MAJOR revision.Usenix Security 2022
Keywords
zero knowledgenetwork protocolsprivacyprobabilistic proofsapplicationsmiddleboxesTLS
Contact author(s)
paulgrubbs12 @ gmail com
History
2022-05-06: last of 4 revisions
2021-08-06: received
See all versions
Short URL
https://ia.cr/2021/1022
License
Creative Commons Attribution
CC BY

BibTeX

@misc{cryptoeprint:2021/1022,
      author = {Paul Grubbs and Arasu Arun and Ye Zhang and Joseph Bonneau and Michael Walfish},
      title = {Zero-Knowledge Middleboxes},
      howpublished = {Cryptology ePrint Archive, Paper 2021/1022},
      year = {2021},
      note = {\url{https://eprint.iacr.org/2021/1022}},
      url = {https://eprint.iacr.org/2021/1022}
}
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