Privacy Considerations for IPv6 Adaptation Layer Mechanisms
draft-ietf-6lo-privacy-considerations-04

Document Type Active Internet-Draft (6lo WG)
Last updated 2016-12-15 (latest revision 2016-10-31)
Replaces draft-thaler-6lo-privacy-considerations
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Network Working Group                                          D. Thaler
Internet-Draft                                                 Microsoft
Intended status: Informational                          October 31, 2016
Expires: May 4, 2017

      Privacy Considerations for IPv6 Adaptation Layer Mechanisms
                draft-ietf-6lo-privacy-considerations-04

Abstract

   This document discusses how a number of privacy threats apply to
   technologies designed for IPv6 over various link layer protocols, and
   provides advice to protocol designers on how to address such threats
   in adaptation layer specifications for IPv6 over such links.

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
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   This Internet-Draft will expire on May 4, 2017.

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   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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Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  Amount of Entropy Needed in Global Addresses  . . . . . . . .   3
   3.  Potential Approaches  . . . . . . . . . . . . . . . . . . . .   4
     3.1.  IEEE-Identifier-Based Addresses . . . . . . . . . . . . .   5
     3.2.  Short Addresses . . . . . . . . . . . . . . . . . . . . .   5
   4.  Recommendations . . . . . . . . . . . . . . . . . . . . . . .   6
   5.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   7
   6.  Security Considerations . . . . . . . . . . . . . . . . . . .   7
   7.  Informative References  . . . . . . . . . . . . . . . . . . .   7
   Author's Address  . . . . . . . . . . . . . . . . . . . . . . . .   9

1.  Introduction

   RFC 6973 [RFC6973] discusses privacy considerations for Internet
   protocols, and Section 5.2 of that document covers a number of
   privacy-specific threats.  In the context of IPv6 addresses,
   Section 3 of [RFC7721] provides further elaboration on the
   applicability of the privacy threats.

   When interface identifiers (IIDs) are generated without sufficient
   entropy compared to the link lifetime, devices and users can become
   vulnerable to the various threats discussed there, including:

   o  Correlation of activities over time, if the same identifier is
      used for traffic over period of time

   o  Location tracking, if the same interface identifier is used with
      different prefixes as a device moves between different networks

   o  Device-specific vulnerability exploitation, if the identifier
      helps identify a vendor or version or protocol and hence suggests
      what types of attacks to try

   o  Address scanning, which enables all of the above attacks by off-
      link attackers.  (On some Non-Broadcast Multi-Access (NBMA) links
      where all nodes aren't already privy to all on-link addresses,
      address scans might also be done by on-link attackers, but in most
      cases address scans are not an interesting threat from on-link
      attackers and thus address scans generally apply only to routable
      addresses.)

   For example, for links that may last for years, "enough" bits of
   entropy means at least 46 or so bits (see Section 2 for why) in a
   routable address; ideally all 64 bits of the IID should be used,
   although historically some bits have been excluded for reasons
   discussed in [RFC7421].  Link-local addresses can also be susceptible

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