DNS-SD Privacy and Security Requirements
draft-ietf-dnssd-prireq-00

Document Type Active Internet-Draft (dnssd WG)
Last updated 2018-09-30
Replaces draft-huitema-dnssd-prireq
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Network Working Group                                         C. Huitema
Internet-Draft                                      Private Octopus Inc.
Intended status: Informational                        September 30, 2018
Expires: April 3, 2019

                DNS-SD Privacy and Security Requirements
                       draft-ietf-dnssd-prireq-00

Abstract

   DNS-SD (DNS Service Discovery) normally discloses information about
   devices offering and 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, serious privacy problems arise.  We analyze the requirements
   of a privacy respecting discovery service.

Status of This Memo

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   This Internet-Draft will expire on April 3, 2019.

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   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
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   include Simplified BSD License text as described in Section 4.e of

Huitema                   Expires April 3, 2019                 [Page 1]
Internet-Draft         DNS-SD Privacy Requirements        September 2018

   the Trust Legal Provisions and are provided without warranty as
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Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
     1.1.  Requirements  . . . . . . . . . . . . . . . . . . . . . .   3
   2.  DNS-SD Discovery Scenarios  . . . . . . . . . . . . . . . . .   3
     2.1.  Private client and public server  . . . . . . . . . . . .   3
     2.2.  Private client and private server . . . . . . . . . . . .   4
     2.3.  Wearable client and server  . . . . . . . . . . . . . . .   5
   3.  Privacy Considerations  . . . . . . . . . . . . . . . . . . .   6
     3.1.  Privacy Implication of Publishing Service Instance Names    7
     3.2.  Privacy Implication of Publishing Node Names  . . . . . .   7
     3.3.  Privacy Implication of Publishing Service Attributes  . .   8
     3.4.  Device Fingerprinting . . . . . . . . . . . . . . . . . .   8
     3.5.  Privacy Implication of Discovering Services . . . . . . .   9
   4.  Security Considerations . . . . . . . . . . . . . . . . . . .  10
     4.1.  Authenticity, Integrity & Freshness . . . . . . . . . . .  10
     4.2.  Confidentiality . . . . . . . . . . . . . . . . . . . . .  10
     4.3.  Resistance to Dictionary Attacks  . . . . . . . . . . . .  10
     4.4.  Resistance to Denial-of-Service Attack  . . . . . . . . .  10
     4.5.  Resistance to Sender Impersonation  . . . . . . . . . . .  11
     4.6.  Sender Deniability  . . . . . . . . . . . . . . . . . . .  11
   5.  Operational Considerations  . . . . . . . . . . . . . . . . .  11
     5.1.  Power Management  . . . . . . . . . . . . . . . . . . . .  11
     5.2.  Protocol Efficiency . . . . . . . . . . . . . . . . . . .  11
     5.3.  Secure Initialization and Trust Models  . . . . . . . . .  12
     5.4.  External Dependencies . . . . . . . . . . . . . . . . . .  13
   6.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .  13
   7.  Acknowledgments . . . . . . . . . . . . . . . . . . . . . . .  13
   8.  Informative References  . . . . . . . . . . . . . . . . . . .  13
   Author's Address  . . . . . . . . . . . . . . . . . . . . . . . .  15

1.  Introduction

   DNS-SD [RFC6763] over mDNS [RFC6762] enables zero-configuration
   service discovery in local networks.  It is very convenient for
   users, but it requires the public exposure of the offering and
   requesting identities along with information about the offered and
   requested services.  Parts of the published information can seriously
   breach the user's privacy.  These privacy issues and potential
   solutions are discussed in [KW14a], [KW14b] and [K17].

   There are cases when nodes connected to a network want to provide or
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