PRECIS Framework: Preparation and Comparison of Internationalized Strings in Application Protocols
draft-ietf-precis-framework-08

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Document Type Active Internet-Draft (precis WG)
Last updated 2013-04-25
Replaces draft-blanchet-precis-framework
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PRECIS                                                    P. Saint-Andre
Internet-Draft                                       Cisco Systems, Inc.
Obsoletes: 3454 (if approved)                                M. Blanchet
Intended status: Standards Track                                Viagenie
Expires: October 27, 2013                                 April 25, 2013

   PRECIS Framework: Preparation and Comparison of Internationalized
                    Strings in Application Protocols
                     draft-ietf-precis-framework-08

Abstract

   Application protocols using Unicode code points in protocol strings
   need to properly prepare such strings in order to perform valid
   comparison operations (e.g., for purposes of authentication or
   authorization).  This document defines a framework enabling
   application protocols to perform the preparation and comparison of
   internationalized strings (a.k.a.  "PRECIS") in a way that depends on
   the properties of Unicode code points and thus is agile with respect
   to versions of Unicode.  As a result, this framework provides a more
   sustainable approach to the handling of internationalized strings
   than the previous framework, known as Stringprep (RFC 3454).  A
   specification that reuses this framework can either directly use the
   PRECIS string classes or subclass the PRECIS string classes as
   needed.  This framework takes an approach similar to the revised
   internationalized domain names (IDNs) in applications (IDNA)
   technology (RFC 5890, RFC 5891, RFC 5892, RFC 5893, RFC 5894) and
   thus adheres to the high-level design goals described in the IAB's
   recommendations regarding IDNs (RFC 4690), albeit for application
   technologies other than the Domain Name System (DNS).  This document
   obsoletes RFC 3454.

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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Saint-Andre & Blanchet  Expires October 27, 2013                [Page 1]
Internet-Draft              PRECIS Framework                  April 2013

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

Copyright Notice

   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
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   described in the Simplified BSD License.

Saint-Andre & Blanchet  Expires October 27, 2013                [Page 2]
Internet-Draft              PRECIS Framework                  April 2013

Table of Contents

   1.  Introduction . . . . . . . . . . . . . . . . . . . . . . . . .  5
   2.  Terminology  . . . . . . . . . . . . . . . . . . . . . . . . .  6
   3.  String Classes . . . . . . . . . . . . . . . . . . . . . . . .  6
     3.1.  Overview . . . . . . . . . . . . . . . . . . . . . . . . .  6
     3.2.  Order of Operations  . . . . . . . . . . . . . . . . . . .  8
     3.3.  IdentifierClass  . . . . . . . . . . . . . . . . . . . . .  8
     3.4.  FreeformClass  . . . . . . . . . . . . . . . . . . . . . . 10
   4.  Use of PRECIS String Classes . . . . . . . . . . . . . . . . . 12
     4.1.  Principles . . . . . . . . . . . . . . . . . . . . . . . . 12
     4.2.  Subclassing  . . . . . . . . . . . . . . . . . . . . . . . 13
     4.3.  Building Application-Layer Constructs  . . . . . . . . . . 14
     4.4.  A Note about Spaces  . . . . . . . . . . . . . . . . . . . 14
   5.  Code Point Properties  . . . . . . . . . . . . . . . . . . . . 15
   6.  Category Definitions Used to Calculate Derived Property
       Value  . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
     6.1.  LetterDigits (A) . . . . . . . . . . . . . . . . . . . . . 17
     6.2.  Unstable (B) . . . . . . . . . . . . . . . . . . . . . . . 17
     6.3.  IgnorableProperties (C)  . . . . . . . . . . . . . . . . . 17
     6.4.  IgnorableBlocks (D)  . . . . . . . . . . . . . . . . . . . 18
     6.5.  LDH (E)  . . . . . . . . . . . . . . . . . . . . . . . . . 18
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