Stringprep Revision and PRECIS Problem Statement
draft-ietf-precis-problem-statement-07

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Document Type Active Internet-Draft (precis WG)
Last updated 2012-08-03
Replaces draft-blanchet-precis-problem-statement
Stream IETF
Intended RFC status Informational
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Stream WG state WG Document Aug 2010
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Responsible AD Pete Resnick
Send notices to precis-chairs@tools.ietf.org, draft-ietf-precis-problem-statement@tools.ietf.org
Network Working Group                                        M. Blanchet
Internet-Draft                                                  Viagenie
Intended status: Informational                               A. Sullivan
Expires: February 4, 2013                                      Dyn, Inc.
                                                          August 3, 2012

            Stringprep Revision and PRECIS Problem Statement
               draft-ietf-precis-problem-statement-07.txt

Abstract

   If a protocol expects to compare two strings and is prepared only for
   those strings to be ASCII, then using Unicode codepoints in those
   strings requires they be prepared somehow.  Internationalizing Domain
   Names in Applications (here called IDNA2003) defined and used
   Stringprep and Nameprep.  Other protocols subsequently defined
   Stringprep profiles.  A new approach different from Stringprep and
   Nameprep is used for a revision of IDNA2003 (called IDNA2008).  Other
   Stringprep profiles need to be similarly updated or a replacement of
   Stringprep needs to be designed.  This document outlines the issues
   to be faced by those designing a Stringprep replacement.

Status of this Memo

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   This Internet-Draft will expire on February 4, 2013.

Copyright Notice

   Copyright (c) 2012 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
   (http://trustee.ietf.org/license-info) in effect on the date of

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   publication of this document.  Please review these documents
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Table of Contents

   1.  Introduction . . . . . . . . . . . . . . . . . . . . . . . . .  5
   2.  Conventions  . . . . . . . . . . . . . . . . . . . . . . . . .  6
   3.  Stringprep Profiles Limitations  . . . . . . . . . . . . . . .  6
   4.  Major Topics for Consideration . . . . . . . . . . . . . . . .  8
     4.1.  Comparison . . . . . . . . . . . . . . . . . . . . . . . .  8
       4.1.1.  Types of Identifiers . . . . . . . . . . . . . . . . .  8
       4.1.2.  Effect of comparison . . . . . . . . . . . . . . . . .  8
     4.2.  Dealing with characters  . . . . . . . . . . . . . . . . .  8
       4.2.1.  Case folding, case sensitivity, and case
               preservation . . . . . . . . . . . . . . . . . . . . .  9
       4.2.2.  Stringprep and NFKC  . . . . . . . . . . . . . . . . .  9
       4.2.3.  Character mapping  . . . . . . . . . . . . . . . . . .  9
       4.2.4.  Prohibited characters  . . . . . . . . . . . . . . . . 10
       4.2.5.  Internal structure, delimiters, and special
               characters . . . . . . . . . . . . . . . . . . . . . . 10
       4.2.6.  Restrictions because of glyph similarity . . . . . . . 11
     4.3.  Where the data comes from and where it goes  . . . . . . . 11
       4.3.1.  User input and the source of protocol elements . . . . 11
       4.3.2.  User output  . . . . . . . . . . . . . . . . . . . . . 11
       4.3.3.  Operations . . . . . . . . . . . . . . . . . . . . . . 12
   5.  Considerations for Stringprep replacement  . . . . . . . . . . 13
   6.  Security Considerations  . . . . . . . . . . . . . . . . . . . 13
   7.  IANA Considerations  . . . . . . . . . . . . . . . . . . . . . 14
   8.  Discussion home for this draft . . . . . . . . . . . . . . . . 14
   9.  Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 14
   10. Informative References . . . . . . . . . . . . . . . . . . . . 14
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