Device Pairing Design Issues
draft-ietf-dnssd-pairing-info-02

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Last updated 2018-10-23
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Network Working Group                                          D. Kaiser
Internet-Draft
Intended status: Informational                                C. Huitema
Expires: April 26, 2019                             Private Octopus Inc.
                                                        October 23, 2018

                      Device Pairing Design Issues
                    draft-ietf-dnssd-pairing-info-02

Abstract

   This document discusses issues and problems occuring in the design of
   device pairing mechanism.  It presents experience with existing
   pairing systems and general user interaction requirements to make the
   case for "short authentication strings".  It then reviews the design
   of cryptographic algorithms designed to maximise the robustness of
   the short authentication string mechanisms, as well as implementation
   considerations such as integration with TLS.

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
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   This Internet-Draft will expire on April 26, 2019.

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
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   (https://trustee.ietf.org/license-info) in effect on the date of
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Kaiser & Huitema         Expires April 26, 2019                 [Page 1]
Internet-Draft            Device Pairing Issues             October 2018

   include Simplified BSD License text as described in Section 4.e of
   the Trust Legal Provisions and are provided without warranty as
   described in the Simplified BSD License.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
     1.1.  Document Organization . . . . . . . . . . . . . . . . . .   3
   2.  Protocol Independent Secure Pairing . . . . . . . . . . . . .   3
   3.  Identity Assurance  . . . . . . . . . . . . . . . . . . . . .   4
   4.  Manual Authentication . . . . . . . . . . . . . . . . . . . .   4
     4.1.  Short PIN Proved Inadequate . . . . . . . . . . . . . . .   4
     4.2.  Push Buttons Just Work, But Are Insecure  . . . . . . . .   5
     4.3.  Short Range Communication . . . . . . . . . . . . . . . .   6
     4.4.  Short Authentication Strings  . . . . . . . . . . . . . .   6
     4.5.  Revisiting the PIN versus SAS discussion  . . . . . . . .   7
   5.  Resist Cryptographic Attacks  . . . . . . . . . . . . . . . .   8
   6.  Privacy Requirements  . . . . . . . . . . . . . . . . . . . .  11
   7.  Using TLS . . . . . . . . . . . . . . . . . . . . . . . . . .  11
   8.  QR codes  . . . . . . . . . . . . . . . . . . . . . . . . . .  12
   9.  Intra User Pairing and Transitive Pairing . . . . . . . . . .  14
   10. Security Considerations . . . . . . . . . . . . . . . . . . .  15
   11. IANA Considerations . . . . . . . . . . . . . . . . . . . . .  15
   12. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . .  15
   13. Informative References  . . . . . . . . . . . . . . . . . . .  15
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  17

1.  Introduction

   To engage in secure and privacy preserving communication, hosts need
   to differentiate between authorized peers, which must both know about
   the host's presence and be able to decrypt messages sent by the host,
   and other peers, which must not be able to decrypt the host's
   messages and ideally should not be aware of the host's presence.  The
   necessary relationship between host and peer can be established by a
   centralized service, e.g. a certificate authority, by a web of trust,
   e.g.  PGP, or -- without using global identities -- by device
   pairing.

   The general pairing requirement is easy to state: establish a trust
   relation between two entities in a secure manner.  But details
   matter, and in this section we explore the detailed requirements that
   will guide the design of a pairing protocol.

   This document does not specify an actual pairing protocol, but it
   served as the basis for the design of the pairing protocol developed
   for DNS-SD privacy [I-D.ietf-dnssd-pairing].  The requirement of a
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