Compact UUIDs for Constrained Grammars
draft-taylor-uuid-ncname-01

Document Type Active Internet-Draft (individual)
Author Dorian Taylor 
Last updated 2021-01-17
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Network Working Group                                          D. Taylor
Internet-Draft                                               Independent
Updates: RFC4122 (if approved)                           15 January 2021
Intended status: Informational                                          
Expires: 19 July 2021

                 Compact UUIDs for Constrained Grammars
                      draft-taylor-uuid-ncname-01

Abstract

   The Universally Unique Identifier is a suitable standard for, as the
   name suggests, uniquely identifying entities in a symbol space large
   enough that the identifiers do not collide.  Many formal grammars,
   however, are too restrictive to permit the use of UUIDs in their
   canonical representation (described in RFC 4122 and elsewhere),
   despite it being useful to do so.  This document specifies an
   alternative compact representation for UUIDs that preserves some
   properties of the canonical form, with three encoding varietals, to
   fit these more restrictive contexts.

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 19 July 2021.

Copyright Notice

   Copyright (c) 2021 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

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   This document is subject to BCP 78 and the IETF Trust's Legal
   Provisions Relating to IETF Documents (https://trustee.ietf.org/
   license-info) in effect on the date of publication of this document.
   Please review these documents carefully, as they describe your rights
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Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
     1.1.  Requirements  . . . . . . . . . . . . . . . . . . . . . .   3
     1.2.  Motivation & Applications . . . . . . . . . . . . . . . .   4
   2.  Terminology . . . . . . . . . . . . . . . . . . . . . . . . .   4
   3.  Strategy  . . . . . . . . . . . . . . . . . . . . . . . . . .   4
   4.  Syntax  . . . . . . . . . . . . . . . . . . . . . . . . . . .   5
     4.1.  Detection Heuristic . . . . . . . . . . . . . . . . . . .   6
     4.2.  Equivalency . . . . . . . . . . . . . . . . . . . . . . .   7
   5.  Algorithms  . . . . . . . . . . . . . . . . . . . . . . . . .   7
     5.1.  Encoding Algorithm  . . . . . . . . . . . . . . . . . . .   7
     5.2.  Decoding Algorithm  . . . . . . . . . . . . . . . . . . .   9
   6.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .  10
   7.  Security Considerations . . . . . . . . . . . . . . . . . . .  10
   8.  Normative References  . . . . . . . . . . . . . . . . . . . .  10
   9.  Informative References  . . . . . . . . . . . . . . . . . . .  11
   Appendix A.  Samples  . . . . . . . . . . . . . . . . . . . . . .  11
   Appendix B.  Implementations  . . . . . . . . . . . . . . . . . .  12
   Author's Address  . . . . . . . . . . . . . . . . . . . . . . . .  13

1.  Introduction

   The formal grammar production "one or more letters or underscores
   followed by zero or more letters, digits, or underscores" (denoted by
   the regular expression "/^[A-Za-z_][0-9A-Za-z_]*$/") is ubiquitous in
   computing.  It is often used for identifiers, and for good reasons.
   We may encounter some variations on this theme, like admitting
   hyphens, dots, or Unicode alphanumerics.  Some systems may impose
   additional constraints, like case-sensitivity (or the lack of it),
   explicit upper- or lower-case letters, or limits on identifier
   length.

   UUIDs are standardized 128-bit identifiers with many useful
   properties, and there are many places where it would make sense to
   use them, but their canonical representation, either with or without
   the URN prefix (see RFC 4122 [RFC4122]) does not conform to the
   constraint described above:

   *  UUIDs contain hyphens (and colons in the case of URNs),

   *  UUIDs potentially start with a digit,

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   *  UUIDs are potentially too long for the slot.

   This leads to developers creating incompatible, ad-hoc solutions.
   The goal of this specification is to address an ostensible need for a
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