Issues in Identifier Comparison for Security Purposes
draft-iab-identifier-comparison-08

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Last updated 2013-02-23
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Network Working Group                                     D. Thaler, Ed.
Internet-Draft                                                 Microsoft
Intended status: Informational                         February 23, 2013
Expires: August 27, 2013

         Issues in Identifier Comparison for Security Purposes
                 draft-iab-identifier-comparison-08.txt

Abstract

   Identifiers such as hostnames, URIs, IP addresses, and email
   addresses are often used in security contexts to identify security
   principals and resources.  In such contexts, an identifier supplied
   via some protocol is often compared using some policy to make
   security decisions such as whether the security principal may access
   the resource, what level of authentication or encryption is required,
   etc.  If the parties involved in a security decision use different
   algorithms to compare identifiers, then failure scenarios ranging
   from denial of service to elevation of privilege can result.  This
   document provides a discussion of these issues that designers should
   consider when defining identifiers and protocols, and when
   constructing architectures that use multiple protocols.

Status of this Memo

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   This Internet-Draft will expire on August 27, 2013.

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   Copyright (c) 2013 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

Thaler                   Expires August 27, 2013                [Page 1]
Internet-Draft            Identifier Comparison            February 2013

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Table of Contents

   1.  Introduction . . . . . . . . . . . . . . . . . . . . . . . . .  3
     1.1.  Canonicalization . . . . . . . . . . . . . . . . . . . . .  5
   2.  Security Uses  . . . . . . . . . . . . . . . . . . . . . . . .  5
     2.1.  Types of Identifiers . . . . . . . . . . . . . . . . . . .  7
     2.2.  False Positives and Negatives  . . . . . . . . . . . . . .  7
     2.3.  Hypothetical Example . . . . . . . . . . . . . . . . . . .  8
   3.  Common Identifiers . . . . . . . . . . . . . . . . . . . . . .  9
     3.1.  Hostnames  . . . . . . . . . . . . . . . . . . . . . . . .  9
       3.1.1.  IPv4 Literals  . . . . . . . . . . . . . . . . . . . . 10
       3.1.2.  IPv6 Literals  . . . . . . . . . . . . . . . . . . . . 12
       3.1.3.  Internationalization . . . . . . . . . . . . . . . . . 12
       3.1.4.  Resolution for comparison  . . . . . . . . . . . . . . 13
     3.2.  Ports and Service Names  . . . . . . . . . . . . . . . . . 14
     3.3.  URIs . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
       3.3.1.  Scheme component . . . . . . . . . . . . . . . . . . . 15
       3.3.2.  Authority component  . . . . . . . . . . . . . . . . . 16
       3.3.3.  Path component . . . . . . . . . . . . . . . . . . . . 16
       3.3.4.  Query component  . . . . . . . . . . . . . . . . . . . 17
       3.3.5.  Fragment component . . . . . . . . . . . . . . . . . . 17
       3.3.6.  Resolution for comparison  . . . . . . . . . . . . . . 17
     3.4.  Email Address-like Identifiers . . . . . . . . . . . . . . 18
   4.  General Issues . . . . . . . . . . . . . . . . . . . . . . . . 18
     4.1.  Conflation . . . . . . . . . . . . . . . . . . . . . . . . 18
     4.2.  Internationalization . . . . . . . . . . . . . . . . . . . 19
     4.3.  Scope  . . . . . . . . . . . . . . . . . . . . . . . . . . 20
     4.4.  Temporality  . . . . . . . . . . . . . . . . . . . . . . . 21
   5.  Security Considerations  . . . . . . . . . . . . . . . . . . . 21
   6.  Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 22
   7.  IANA Considerations  . . . . . . . . . . . . . . . . . . . . . 22
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