Network-Based Website Fingerprinting
draft-irtf-pearg-website-fingerprinting-01

Document Type Active Internet-Draft (pearg RG)
Authors Ian Goldberg  , Tao Wang  , Christopher Wood 
Last updated 2020-09-08
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pearg                                                        I. Goldberg
Internet-Draft                                    University of Waterloo
Intended status: Informational                                   T. Wang
Expires: March 12, 2021          HK University of Science and Technology
                                                               C.A. Wood
                                                             Apple, Inc.
                                                       September 8, 2020

                  Network-Based Website Fingerprinting
               draft-irtf-pearg-website-fingerprinting-01

Abstract

   The IETF is well on its way to protecting connection metadata with
   protocols such as DNS-over-TLS and DNS-over-HTTPS, and work-in-
   progress towards encrypting the TLS SNI.  However, more work is
   needed to protect traffic metadata, especially in the context of web
   traffic.  In this document, we survey Website Fingerprinting attacks,
   which are a class of attacks that use machine learning techniques to
   attack web privacy, and highlight metadata leaks used by said
   attacks.  We also survey proposed mitigations for such leakage and
   discuss their applicability to IETF protocols such as TLS, QUIC, and
   HTTP.  We endeavor to show that Website Fingerprinting attacks are a
   serious problem that affect all Internet users, and we pose open
   problems and directions for future research in this area.

Note to Readers

   Source for this draft and an issue tracker can be found at
   https://github.com/chris-wood/ietf-fingerprinting
   (https://github.com/chris-wood/ietf-fingerprinting).

Status of This Memo

   This Internet-Draft is submitted in full conformance with the
   provisions of BCP 78 and BCP 79.

   Internet-Drafts are working documents of the Internet Engineering
   Task Force (IETF).  Note that other groups may also distribute
   working documents as Internet-Drafts.  The list of current Internet-
   Drafts is at https://datatracker.ietf.org/drafts/current/.

   Internet-Drafts are draft documents valid for a maximum of six months
   and may be updated, replaced, or obsoleted by other documents at any
   time.  It is inappropriate to use Internet-Drafts as reference
   material or to cite them other than as "work in progress."

Goldberg, et al.         Expires March 12, 2021                 [Page 1]
Internet-Draft    Network-Based Website Fingerprinting    September 2020

   This Internet-Draft will expire on March 12, 2021.

Copyright Notice

   Copyright (c) 2020 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

   This document is subject to BCP 78 and the IETF Trust's Legal
   Provisions Relating to IETF Documents (https://trustee.ietf.org/
   license-info) in effect on the date of publication of this document.
   Please review these documents carefully, as they describe your rights
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   extracted from this document must include Simplified BSD License text
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   provided without warranty as described in the Simplified BSD License.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  Background  . . . . . . . . . . . . . . . . . . . . . . . . .   4
   3.  Website Fingerprinting  . . . . . . . . . . . . . . . . . . .   4
   4.  Attacks . . . . . . . . . . . . . . . . . . . . . . . . . . .   5
   5.  Base Rate Fallacy . . . . . . . . . . . . . . . . . . . . . .   8
   6.  Defenses  . . . . . . . . . . . . . . . . . . . . . . . . . .   9
     6.1.  Traffic Morphing  . . . . . . . . . . . . . . . . . . . .   9
     6.2.  Traffic Splitting . . . . . . . . . . . . . . . . . . . .  13
   7.  Open Problems and Directions  . . . . . . . . . . . . . . . .  13
   8.  Protocol Design Considerations  . . . . . . . . . . . . . . .  15
   9.  Security Considerations . . . . . . . . . . . . . . . . . . .  15
   10. IANA Considerations . . . . . . . . . . . . . . . . . . . . .  15
   11. Informative References  . . . . . . . . . . . . . . . . . . .  15
   Appendix A.  Acknowledgements . . . . . . . . . . . . . . . . . .  22
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  22

1.  Introduction

   Internet protocols such as TLS 1.3 [RFC8446] and QUIC
   [I-D.ietf-quic-transport] bring substantial improvements to end-
   users.  The IETF engineered these with security and privacy in mind
   by encrypting more protocol messages using modern cryptographic
   primitives and algorithms, and engineering against flaws found in
   previous protocols, yielding several desirable security properties,
   including: forward-secure session key secrecy, downgrade protection,
   key compromise impersonation resistance, and protection of endpoint
   identities.  Combined, these two protocols are set to protect a
   significant amount of Internet data.  However, significant metadata
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