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IODEF Enumeration Reference Format
draft-ietf-mile-enum-reference-format-00

The information below is for an old version of the document.
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This is an older version of an Internet-Draft that was ultimately published as RFC 7495.
Author Adam W. Montville
Last updated 2013-07-15
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draft-ietf-mile-enum-reference-format-00
INTERNET-DRAFT                                         Adam W. Montville
Intended Status: Standards Track                                   (CIS)
Expires: January 15, 2014                                  July 14, 2013

                  IODEF Enumeration Reference Format 
                draft-ietf-mile-enum-reference-format-00

Abstract

   The Incident Object Description Exchange Format [IODEF] provides a
   Reference class used to reference external entities (such as
   enumeration identifiers).  However, the method of external entity
   identification has been left unstructured.  This document describes a
   method to provide structure for referencing external entities for the
   [IODEF] Reference class.

Status of this Memo

   This Internet-Draft is submitted to IETF in full conformance with the
   provisions of BCP 78 and BCP 79.

   Internet-Drafts are working documents of the Internet Engineering
   Task Force (IETF), its areas, and its working groups.  Note that
   other groups may also distribute working documents as
   Internet-Drafts.

   Internet-Drafts are draft documents valid for a maximum of six months
   and may be updated, replaced, or obsoleted by other documents at any
   time.  It is inappropriate to use Internet-Drafts as reference
   material or to cite them other than as "work in progress."

   The list of current Internet-Drafts can be accessed at
   http://www.ietf.org/1id-abstracts.html

   The list of Internet-Draft Shadow Directories can be accessed at
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Copyright and License 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
 

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   (http://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 and restrictions with respect
   to this document. Code Components extracted from this document must
   include Simplified BSD License text as described in Section 4.e of
   the Trust Legal Provisions and are provided without warranty as
   described in the Simplified BSD License.

Table of Contents

   1  Introduction  . . . . . . . . . . . . . . . . . . . . . . . . .  3
     1.1  Terminology . . . . . . . . . . . . . . . . . . . . . . . .  3
   2.  Referencing External Enumerations  . . . . . . . . . . . . . .  3
   3  Security Considerations . . . . . . . . . . . . . . . . . . . .  5
   4  IANA Considerations . . . . . . . . . . . . . . . . . . . . . .  5
   5 XML Schema . . . . . . . . . . . . . . . . . . . . . . . . . . .  6
   6  References  . . . . . . . . . . . . . . . . . . . . . . . . . .  6
     6.1  Normative References  . . . . . . . . . . . . . . . . . . .  6
     6.2  Informative References  . . . . . . . . . . . . . . . . . .  7
   Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . .  7

 

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1  Introduction

   There is an identified need to specify a format to include relevant
   enumeration values in an IODEF document.  It is anticipated that this
   requirement will exist in other standardization efforts within
   several IETF Working Groups, but the scope of this document pertains
   solely to [IODEF].

1.1  Terminology

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
   document are to be interpreted as described in RFC 2119 [RFC2119].

2.  Referencing External Enumerations

   The need is to place enumeration identifiers and their references in
   [IODEF]'s Reference class.  There are several ways to accomplish this
   goal, but the most appropriate at this point is to require a specific
   format for the ReferenceName string of the [IODEF] Reference class,
   such that an IANA table can be used to catalog a variety of reference
   types.

      +------------------+
      | Reference        |
      +------------------+
      |                  |<>----------[ ReferenceName ]
      |                  |<>--{0..*}--[ URL           ]
      |                  |<>--{0..*}--[ Description   ]
      +------------------+

                   FIGURE 1: [IODEF] Reference Class 

   Per [IODEF] the ReferenceName is of type ML_STRING.  This becomes
   problematic when specific references, especially enumerations such as
   [CVE], [CCE], [CPE] and so on, are referenced - how is an implementer
   to know which type of reference this is, and thus how to parse it?
   One solution, presented here, is to require that ReferenceName follow
   a particular format. 

 2.1 Reference Name Format

   The Reference Name Format uses XML to provide the structure for
   enumeration identification, and requries that a specific Abbreviation
   and RegistryVersion be associated with the ID. An implementer can
   look up the ID type (as referenced by the logical tuple of
   Abbreviation and RegistryVersion) in the IANA table (see Section 4)
 

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   to understand how the ID is structured.

      <Reference>
         <ReferenceName>
            <EnumRef>
               <Abbreviation>CXI</Abbreviation>
               <RegistryVersion>1</RegistryVersion>
               <ID>CXI-1234-XYZ</ID>
            </EnumRef>
         </ReferenceName>
         <URL>http://cxi.example.com</URL>
         <Description>Foo</Description>
      </Reference>

   Information in the IANA table (see Section 4) would include:

      Full Name: Concept X Identifier
      Abbreviation: CXI
      Registry Version: 1
      Enumeration Version: any
      Specification URI: http://cxi.example.com/spec_url

 2.3 Reference Method Applicability

      While the scope of this document pertains to [IODEF], it should be
      readily apparent that any standard needing to reference an
      enumeration identified by a specially formatted string can use
      this method of providing structure after the standard has been
      published.  In effect, this method provides a standardized
      interface for enumerations, thus allowing a loose coupling between
      a given standard and the enumeration identifiers it needs to
      reference now and in the future.

 

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3  Security Considerations

      None.

4  IANA Considerations

      This document specifies an identifier format for the [IODEF]
      ReferenceName string of the Reference class.

      This memo creates the following registry for IANA to manage:

      Name of the Registry: "Enumeration Reference Type Identifiers"

      Note that certain name requests should not be permitted as either
      Full Name or Abbreviation entries for the requested IANA table. 

      Fields to record in the registry: 

         Full Name: The full name of the enumeration as a string from
         the ASCII character set.

         Abbreviation: The abbreviation of the enumeration as a string
         from the ASCII character set.  An abbreviation may be an
         initialism or acronym, is free-form, but is limited to between
         two and ten upper-case characters (used to avoid case-specific
         mismatch errors) meeting the regular expression (between the
         quotes; Perl Regular Expressions): ^[A-Z]{2,20}$ 

         Registry Version: The IANA-registry-specific version to which
         an enumeration identifier pertains as an integer greater than
         zero.  The Registry Version is intended to be incremented for
         each new entry, which permits any string representation for the
         Enumeration Version, but explicitly structures enumeration ID
         versions for the purpose of the registry.

         Enumeration Version: The version of the enumeration as a free-
         form string from the ASCII character set.  

         Specification URI: A list of one or more URIs [RFC3986] from
         which the registered specification can be obtained.  The
         registered specification MUST be readily and publicly available
         from that URI.

      Initial registry contents: None.

      Allocation Policy: Expert Review [RFC5226] and Specification
      Required [RFC5226]
 

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   The Designated Expert is expected to consult with the MILE (Managed
   Incident Lightweight Exchange) working group or its successor if any
   such WG exists (e.g., via email to the working group's mailing list).
   The Designated Expert is expected to review the request and validate
   the appropriateness of the enumeration for the attribute.  If a
   specification is associated with the request, it MUST be reviewed by
   the Designated Expert.

   The Designated Expert will need to ensure the Full Name or
   Abbreviation entry under consideration is appropriate for the problem
   domain and that information at the Specification URI is sufficient
   for unambiguously parsing the identifier. The Designated Expert
   should also validate that the next appropriate Registry Version is
   being used for a new registration. Additionally, the Designated
   Expert should prefer short Abbreviations over long ones.

5 XML Schema

      <?xml version="1.0" encoding="UTF-8"?>
      <xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema"
        elementFormDefault="qualified">
        <xs:element name="EnumRef">
          <xs:complexType>
            <xs:sequence>
              <xs:element ref="Abbreviation"/>
              <xs:element ref="RegistryVersion"/>
              <xs:element ref="ID"/>
            </xs:sequence>
          </xs:complexType>
        </xs:element>
        <xs:element name="Abbreviation" type="xs:NCName"/>
        <xs:element name="RegistryVersion" type="xs:integer"/>
        <xs:element name="ID" type="xs:NCName"/>
      </xs:schema>

6  References

6.1  Normative References

   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119, March 1997.

   [IODEF]    Danyliw, R., Meijer, J., and Y. Demchenko, "The Incident
              Object Description Exchange Format", RFC 5070, December
              2007.

   [3986]     Narten, T. and H. Alvestrand, "Guidelines for Writing an
              IANA Considerations Section in RFCs", BCP 26, RFC 5226,
 

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              May 2008.

6.2  Informative References

   [CCE] http://cce.mitre.org

   [CPE] http://cpe.mitre.org

   [CVE] http://cve.mitre.org

Authors' Addresses

   Adam W. Montville
   Center for Internet Security

   EMail: adam.montville@cisecurity.org

   David Black
   EMC, Inc.

   EMail: david.black@emc.com

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