Privacy Extensions for DNS-SD
draft-ietf-dnssd-privacy-03

Document Type Active Internet-Draft (dnssd WG)
Last updated 2017-09-10
Replaces draft-huitema-dnssd-privacy
Stream IETF
Intended RFC status Proposed Standard
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Stream WG state Waiting for WG Chair Go-Ahead (wg milestones: Oct 2016 - Adopt privacy extens..., Sep 2017 - Submit Privacy Exten... )
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IESG IESG state I-D Exists
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Network Working Group                                         C. Huitema
Internet-Draft                                      Private Octopus Inc.
Intended status: Standards Track                               D. Kaiser
Expires: March 14, 2018                           University of Konstanz
                                                      September 10, 2017

                     Privacy Extensions for DNS-SD
                      draft-ietf-dnssd-privacy-03

Abstract

   DNS-SD (DNS Service Discovery) normally discloses information about
   both the devices offering services and the devices requesting
   services.  This information includes host names, network parameters,
   and possibly a further description of the corresponding service
   instance.  Especially when mobile devices engage in DNS Service
   Discovery over Multicast DNS at a public hotspot, a serious privacy
   problem arises.

   We propose to solve this problem by a two-stage approach.  In the
   first stage, hosts discover Private Discovery Service Instances via
   DNS-SD using special formats to protect their privacy.  These service
   instances correspond to Private Discovery Servers running on peers.
   In the second stage, hosts directly query these Private Discovery
   Servers via DNS-SD over TLS.  A pairwise shared secret necessary to
   establish these connections is only known to hosts authorized by a
   pairing system.

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."

   This Internet-Draft will expire on March 14, 2018.

Huitema & Kaiser         Expires March 14, 2018                 [Page 1]
Internet-Draft          DNS-SD Privacy Extensions         September 2017

Copyright Notice

   Copyright (c) 2017 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
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Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   3
     1.1.  Requirements  . . . . . . . . . . . . . . . . . . . . . .   4
   2.  Privacy Implications of DNS-SD  . . . . . . . . . . . . . . .   4
     2.1.  Privacy Implication of Publishing Service Instance Names    4
     2.2.  Privacy Implication of Publishing Node Names  . . . . . .   5
     2.3.  Privacy Implication of Publishing Service Attributes  . .   5
     2.4.  Device Fingerprinting . . . . . . . . . . . . . . . . . .   6
     2.5.  Privacy Implication of Discovering Services . . . . . . .   7
   3.  Design of the Private DNS-SD Discovery Service  . . . . . . .   7
     3.1.  Device Pairing  . . . . . . . . . . . . . . . . . . . . .   8
     3.2.  Discovery of the Private Discovery Service  . . . . . . .   8
       3.2.1.  Obfuscated Instance Names . . . . . . . . . . . . . .   9
       3.2.2.  Using a Predictable Nonce . . . . . . . . . . . . . .   9
       3.2.3.  Using a Short Proof . . . . . . . . . . . . . . . . .  10
       3.2.4.  Direct Queries  . . . . . . . . . . . . . . . . . . .  12
     3.3.  Private Discovery Service . . . . . . . . . . . . . . . .  12
       3.3.1.  A Note on Private DNS Services  . . . . . . . . . . .  13
     3.4.  Randomized Host Names . . . . . . . . . . . . . . . . . .  14
     3.5.  Timing of Obfuscation and Randomization . . . . . . . . .  14
   4.  Private Discovery Service Specification . . . . . . . . . . .  14
     4.1.  Host Name Randomization . . . . . . . . . . . . . . . . .  15
     4.2.  Device Pairing  . . . . . . . . . . . . . . . . . . . . .  15
     4.3.  Private Discovery Server  . . . . . . . . . . . . . . . .  15
       4.3.1.  Establishing TLS Connections  . . . . . . . . . . . .  15
     4.4.  Publishing Private Discovery Service Instances  . . . . .  16
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