Privacy Extensions for DNS-SD
draft-huitema-dnssd-privacy-00

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Document Type Active Internet-Draft (individual)
Author Christian Huitema 
Last updated 2016-03-09
Replaced by draft-ietf-dnssd-privacy
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Network Working Group                                         C. Huitema
Internet-Draft                                                 Microsoft
Intended status: Standards Track                           March 9, 2016
Expires: September 10, 2016

                     Privacy Extensions for DNS-SD
                   draft-huitema-dnssd-privacy-00.txt

Abstract

   DNS-SD allows discovery of services published in DNS or MDNS.  The
   publication normally disclose information about the device publishing
   the services.  There are use cases where devices want to communicate
   without disclosing their identity, for example two mobile devices
   visiting the same hotspot.  We propose a method to obfuscate the
   identification information published by DNS-SD.

Status of This Memo

   This Internet-Draft is submitted in full conformance with the
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   This Internet-Draft will expire on September 10, 2016.

Copyright Notice

   Copyright (c) 2016 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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Huitema                Expires September 10, 2016               [Page 1]
Internet-Draft          DNS-SD Privacy Extensions             March 2016

   the Trust Legal Provisions and are provided without warranty as
   described in the Simplified BSD License.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
     1.1.  Requirements  . . . . . . . . . . . . . . . . . . . . . .   3
   2.  Privacy implications of DNS-SD  . . . . . . . . . . . . . . .   3
     2.1.  Privacy implication of publishing instance names  . . . .   3
     2.2.  Privacy implication of publishing node names  . . . . . .   4
     2.3.  Privacy implication of publishing service attributes  . .   4
     2.4.  Device fingerprinting . . . . . . . . . . . . . . . . . .   5
     2.5.  Privacy implication of discovering services . . . . . . .   5
   3.  Design of DNS-SD privacy mitigations  . . . . . . . . . . . .   5
     3.1.  Obfuscated instance names . . . . . . . . . . . . . . . .   5
     3.2.  Randomized host names . . . . . . . . . . . . . . . . . .   6
     3.3.  Timing of obfuscation and randomization . . . . . . . . .   7
     3.4.  Fingerprint resistance  . . . . . . . . . . . . . . . . .   7
     3.5.  A note on Private DNS services  . . . . . . . . . . . . .   7
   4.  Privacy extensions for DNS-SD . . . . . . . . . . . . . . . .   8
     4.1.  Randomized Host Name  . . . . . . . . . . . . . . . . . .   8
     4.2.  Instance Discovery Key  . . . . . . . . . . . . . . . . .   8
     4.3.  Composing Obfuscated Instance Names . . . . . . . . . . .   9
     4.4.  De-Obfuscation of Instance Names  . . . . . . . . . . . .   9
   5.  Security Considerations . . . . . . . . . . . . . . . . . . .  10
   6.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .  10
   7.  Acknowledgments . . . . . . . . . . . . . . . . . . . . . . .  10
   8.  References  . . . . . . . . . . . . . . . . . . . . . . . . .  11
     8.1.  Normative References  . . . . . . . . . . . . . . . . . .  11
     8.2.  Informative References  . . . . . . . . . . . . . . . . .  11
   Author's Address  . . . . . . . . . . . . . . . . . . . . . . . .  12

1.  Introduction

   There are cases when nodes connected to a network want to provide or
   consume services without exposing their identity to the other parties
   connected to the same network.  Consider for example a traveller
   wanting to upload pictures from a phone to a laptop when connected to
   the Wi-Fi network of an Internet cafe, or two travellers who want to
   share files between their laptops when waiting for their plane in an
   airport lounge.

   We expect that these exchanges will start with a discovery procedure
   using DNS-SD [RFC6763].  One of the devices will publish the
   availability of a service, such as a picture library or a file store
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