Privacy Extensions for DNS-SD
draft-ietf-dnssd-privacy-05

Document Type Active Internet-Draft (dnssd WG)
Last updated 2018-10-15
Replaces draft-huitema-dnssd-privacy
Stream IETF
Intended RFC status Proposed Standard
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Stream WG state Held by WG (wg milestones: Oct 2016 - Adopt privacy extens..., Sep 2017 - Submit Privacy Exten... )
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Network Working Group                                         C. Huitema
Internet-Draft                                      Private Octopus Inc.
Intended status: Standards Track                               D. Kaiser
Expires: April 18, 2019                           University of Konstanz
                                                        October 15, 2018

                     Privacy Extensions for DNS-SD
                      draft-ietf-dnssd-privacy-05

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.

   Revisions of this draft are currently considered in the DNSSD working
   group.

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 April 18, 2019.

Huitema & Kaiser         Expires April 18, 2019                 [Page 1]
Internet-Draft          DNS-SD Privacy Extensions           October 2018

Copyright Notice

   Copyright (c) 2018 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
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   described in the Simplified BSD License.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   3
     1.1.  Requirements  . . . . . . . . . . . . . . . . . . . . . .   4
   2.  Design of the Private DNS-SD Discovery Service  . . . . . . .   4
     2.1.  Device Pairing  . . . . . . . . . . . . . . . . . . . . .   5
     2.2.  Discovery of the Private Discovery Service  . . . . . . .   5
       2.2.1.  Obfuscated Instance Names . . . . . . . . . . . . . .   5
       2.2.2.  Using a Predictable Nonce . . . . . . . . . . . . . .   6
       2.2.3.  Using a Short Proof . . . . . . . . . . . . . . . . .   7
       2.2.4.  Direct Queries  . . . . . . . . . . . . . . . . . . .   8
     2.3.  Private Discovery Service . . . . . . . . . . . . . . . .   9
       2.3.1.  A Note on Private DNS Services  . . . . . . . . . . .  10
     2.4.  Randomized Host Names . . . . . . . . . . . . . . . . . .  11
     2.5.  Timing of Obfuscation and Randomization . . . . . . . . .  11
   3.  Private Discovery Service Specification . . . . . . . . . . .  11
     3.1.  Host Name Randomization . . . . . . . . . . . . . . . . .  12
     3.2.  Device Pairing  . . . . . . . . . . . . . . . . . . . . .  12
     3.3.  Private Discovery Server  . . . . . . . . . . . . . . . .  12
       3.3.1.  Establishing TLS Connections  . . . . . . . . . . . .  12
     3.4.  Publishing Private Discovery Service Instances  . . . . .  13
     3.5.  Discovering Private Discovery Service Instances . . . . .  14
     3.6.  Direct Discovery of Private Discovery Service Instances .  15
     3.7.  Using the Private Discovery Service . . . . . . . . . . .  16
   4.  Security Considerations . . . . . . . . . . . . . . . . . . .  16
     4.1.  Attacks Against the Pairing System  . . . . . . . . . . .  16
     4.2.  Denial of Discovery of the Private Discovery Service  . .  16
     4.3.  Replay Attacks Against Discovery of the Private Discovery
           Service . . . . . . . . . . . . . . . . . . . . . . . . .  17
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