Network Working Group                                           J. Arkko
Internet-Draft                                                  Ericsson
Intended status: Informational                               C. Jennings
Expires: May 3, 2018                                               Cisco
                                                               Z. Shelby
                                                        October 30, 2017

             Uniform Resource Names for Device Identifiers


   This memo describes a new Uniform Resource Name (URN) namespace for
   hardware device identifiers.  A general representation of device
   identity can be useful in many applications, such as in sensor data
   streams and storage, or equipment inventories.  A URN-based
   representation can be easily passed along in any application that
   needs the information.

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
   Task Force (IETF).  Note that other groups may also distribute
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   Drafts is at

   Internet-Drafts are draft documents valid for a maximum of six months
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   time.  It is inappropriate to use Internet-Drafts as reference
   material or to cite them other than as "work in progress."

   This Internet-Draft will expire on May 3, 2018.

Copyright Notice

   Copyright (c) 2017 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
   ( in effect on the date of
   publication of this document.  Please review these documents
   carefully, as they describe your rights and restrictions with respect

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   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  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  Requirements language . . . . . . . . . . . . . . . . . . . .   3
   3.  DEV URN Definition  . . . . . . . . . . . . . . . . . . . . .   3
   4.  DEV URN Subtypes  . . . . . . . . . . . . . . . . . . . . . .   5
     4.1.  MAC Addresses . . . . . . . . . . . . . . . . . . . . . .   5
     4.2.  1-Wire Device Identifiers . . . . . . . . . . . . . . . .   6
     4.3.  Organization-Defined Identifiers  . . . . . . . . . . . .   6
   5.  Examples  . . . . . . . . . . . . . . . . . . . . . . . . . .   6
   6.  Security Considerations . . . . . . . . . . . . . . . . . . .   7
   7.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   8
   8.  References  . . . . . . . . . . . . . . . . . . . . . . . . .   8
     8.1.  Normative References  . . . . . . . . . . . . . . . . . .   8
     8.2.  Informative References  . . . . . . . . . . . . . . . . .   9
   Appendix A.  Changes from Previous Version  . . . . . . . . . . .  11
   Appendix B.  Acknowledgments  . . . . . . . . . . . . . . . . . .  12
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  12

1.  Introduction

   This memo describes a new Uniform Resource Name (URN) [RFC2141]
   [RFC3406] namespace for hardware device identifiers.  A general
   representation of device identity can be useful in many applications,
   such as in sensor data streams and storage, or equipment inventories
   [RFC7252], [I-D.ietf-core-senml].  A URN-based representation can be
   easily passed along in any application that needs the information, as
   it fits in protocols mechanisms that are designed to carry URNs
   [RFC2616], [RFC3261], [RFC7252].  Finally, URNs can also be easily
   carried and stored in formats such as XML [W3C.REC-xml-19980210] or
   JSON [I-D.ietf-core-senml] [RFC4627].  Using URNs in these formats is
   often preferable as they are universally recognized, self-describing,
   and therefore avoid the need for agreeing to interpret an octet
   string as a specific form of a MAC address, for instance.

   This memo defines identity URN types for situations where no such
   convenient type already exist.  For instance, [RFC6920] defines
   cryptographic identifiers, [RFC7254] defines International Mobile
   station Equipment Identity (IMEI) identifiers for use with 3GPP
   cellular systems, and [I-D.atarius-dispatch-meid-urn] defines Mobile
   Equipment Identity (MEID) identifiers for use with 3GPP2 cellular
   systems.  Those URN types should be employed when such identities are

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   transported; this memo does not redefine these identifiers in any

   Universally Unique IDentifier (UUID) URNs [RFC4122] are another
   alternative way for representing device identifiers, and already
   support MAC addresses as one of type of an identifier.  However,
   UUIDs can be inconvenient in environments where it is important that
   the identifiers are as simple as possible and where additional
   requirements on stable storage, real-time clocks, and identifier
   length can be prohibitive.  UUID-based identifiers are recommended
   for all general purpose uses when MAC addresses are available as
   identifiers.  The device URN defined in this memo is recommended for
   constrained environments.

   Future device identifier types can extend the device device URN type
   defined here, or define their own URNs.

   Note that long-term stable unique identifiers are problematic for
   privacy reasons and should be used with care or avoided as described
   in [RFC7721].

   The rest of this memo is organized as follows.  Section 3 defines the
   "DEV" URN type, and Section 4 defines subtypes for IEEE MAC-48,
   EUI-48 and EUI-64 addresses and 1-wire device identifiers.  Section 5
   gives examples.  Section 6 discusses the security considerations of
   the new URN type.  Finally, Section 7 specifies the IANA registration
   for the new URN type and sets requirements for subtype allocations
   within this type.

2.  Requirements language

   In this document, the key words "MAY", "MUST, "MUST NOT", "OPTIONAL",
   "RECOMMENDED", "SHOULD", and "SHOULD NOT", are to be interpreted as
   described in [RFC2119].

3.  DEV URN Definition

   Namespace ID: "dev" requested

   Registration Information: This is the first registration of this
   namespace, 2011-08-27.

   Registration version number: 1

   Registration date: 2011-08-27

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   Declared registrant of the namespace: IETF and the CORE working
   group.  Should the working group cease to exist, discussion should be
   directed to the general IETF discussion forums or the IESG.

   Declaration of syntactic structure: The identifier is expressed in
   ASCII (UTF-8) characters and has a hierarchical structure as follows:

     devurn = "urn:dev:" body componentpart
     body = macbody / owbody / orgbody / otherbody
     macbody = "mac:" hexstring
     owbody = "ow:" hexstring
     orgbody = "dn:" number ":" identifier
     otherbody = subtype ":" identifier
     subtype = ALPHA *(DIGIT / ALPHA)
     identifier = 1*unreservednout
     unreservednout = ALPHA / DIGIT / "-" / "."
     componentpart = [ "_" component [ componentpart ]]
     component = *1(DIGIT / ALPHA)
     hexstring = hexbyte /
                 hexbyte hexstring
     hexbyte = hexdigit hexdigit
     hexdigit = DIGIT / hexletter
     hexletter = "a" / "b" / "c" / "d" / "e" / "f"
     number = *1DIGIT

   The above Augmented Backus-Naur Form (ABNF) uses the DIGIT and ALPHA
   rules defined in [RFC5234], which are not repeated here.  The rule
   for unreserved is defined in Section 2.3 of [RFC3986].

   The device identity namespace includes three subtypes, and more may
   be defined in the future as specified in Section 7.

   The optional components following the hexstring are strings depicting
   individual aspects of a device.  The specific strings and their
   semantics are up to the designers of the device, but could be used to
   refer to specific interfaces or functions within the device.

   Relevant ancillary documentation: See Section 4.

   Identifier uniqueness considerations: Device identifiers are
   generally expected to be unique, barring the accidental issue of
   multiple devices with the same identifiers.

   Identifier persistence considerations: This URN type SHOULD only be
   used for persistent identifiers, such as hardware-based identifiers
   or cryptographic identifiers based on keys intended for long-term

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   Process of identifier assignment: The process for identifier
   assignment is dependent on the used subtype, and documented in the
   specific subsection under Section 4.

   Process for identifier resolution: The device identities are not
   expected to be globally resolvable.  No identity resolution system is
   expected.  Systems may perform local matching of identities to
   previously seen identities or configured information, however.

   Rules for Lexical Equivalence: The lexical equivalence of the DEV URN
   is defined as an exact and case sensitive string match.  Note that
   the two subtypes defined in this document use only lower case
   letters, however.  Future types might use identifiers that require
   other encodings that require a more full-blown character set (such as
   BASE64), however.

   Conformance with URN Syntax: The string representation of the device
   identity URN and of the MEID sub namespace is fully compatible with
   the URN syntax.

   Validation Mechanism: Specific subtypes may be validated through
   mechanisms discussed in Section 4.

   Scope: DEV URN is global in scope.

4.  DEV URN Subtypes

4.1.  MAC Addresses

   DEV URNs of the "mac" subtype are based on the EUI-64 identifier
   [IEEE.EUI64] derived from a device with a built-in 64-bit EUI-64.
   The EUI-64 is formed from 24 or 36 bits of organization identifier
   followed by 40 or 28 bits of device-specific extension identifier
   assigned by that organization.

   In the DEV URN "mac" subtype the hexstring is simply the full EUI-64
   identifier represented as a hexadecimal string.  It is always exactly
   16 characters long.

   MAC-48 and EUI-48 identifiers are also supported by the same DEV URN
   subtype.  To convert a MAC-48 address to an EUI-64 identifier, The
   OUI of the Ethernet address (the first three octets) becomes the
   organization identifier of the EUI-64 (the first three octets).  The
   fourth and fifth octets of the EUI are set to the fixed value FFFF
   hexadecimal.  The last three octets of the Ethernet address become
   the last three octets of the EUI-64.  The same process is used to
   convert an EUI-48 identifier, but the fixed value FFFE is used

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   Identifier assignment for all of these identifiers rests within the

4.2.  1-Wire Device Identifiers

   The 1-Wire* system is a device communications bus system designed by
   Dallas Semiconductor Corporation. 1-Wire devices are identified by a
   64-bit identifier that consists of 8 byte family code, 48 bit
   identifier unique within a family, and 8 bit CRC code [OW].

      *) 1-Wire is a registered trademark.

   In DEV URNs with the "ow" subtype the hexstring is a representation
   of the full 64 bit identifier as a hexadecimal string.  It is always
   exactly 16 characters long.  Note that the last two characters
   represent the 8-bit CRC code.  Implementations MAY check the validity
   of this code.

   Family code and identifier assignment for all 1-wire devices rests
   with the manufacturers.

4.3.  Organization-Defined Identifiers

   Device identifiers that have only a meaning within an organisation
   can also be used to represent vendor-specific or experimental
   identifiers or identifiers designed for use within the context of an
   organisation.  Organisations are identified by the Private Enterprise
   Number [RFC2578].

5.  Examples

   The following three examples provide examples of MAC-based, 1-Wire,
   and Cryptographic identifiers:

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       urn:dev:mac:0024befffe804ff1            # The MAC address of
                                               # Jari's laptop

       urn:dev:ow:10e2073a01080063             # The 1-Wire temperature
                                               # sensor in Jari's
                                               # kitchen

       urn:dev:ow:264437f5000000ed_humidity    # The laundry sensor's
                                               # humidity part

       urn:dev:ow:264437f5000000ed_temperature # The laundry sensor's
                                               # temperature part

       urn:dev:org:32473:123456                # Device 123456 in
                                               # the RFC 5612 example
                                               # organisation

6.  Security Considerations

   On most devices, the user can display device identifiers.  Depending
   on circumstances, device identifiers may or may not be modified or
   tampered by the user.  An implementation of the DEV URN MUST NOT
   change these properties from what they were intended.  In particular,
   a device identifier that is intended to be immutable should not
   become mutable as a part of implementing the DEV URN type.  More
   generally, nothing in this memo should be construed to override what
   the relevant device specifications have already said about the

   Other devices in the same network may or may not be able to identify
   the device.  For instance, on Ethernet network, the MAC address of a
   device is visible to all other devices.

   The URNs generated according to the rules defined in this document
   result in long-term stable unique identifiers for the devices.  Such
   identifiers may have privacy and security implications because they
   may enable correlating information about a specific device over a
   long period of time, location tracking, and device specific
   vulnerability exploitation [RFC7721].  Also, usually there is no easy
   way to change the identifier.  Therefore these identifiers need to be
   used with care and especially care should be taken avoid leaking them
   outside of the system that is intended to use the identifiers.

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7.  IANA Considerations

   This document requests the registration of a new URN namespace for
   "DEV", as described in Section 3.

   Additional subtypes for DEV URNs can be defined through IETF Review
   or IESG Approval [RFC5226].

   Such allocations are appropriate when there is a new namespace of
   some type of device identifiers, defined in stable fashion and with a
   publicly available specification that can be pointed to.

   Note that the organisation (Section 4.3) device identifiers can also
   be used in some cases, at least as a temporary measure.  It is
   preferrable, however, that long-term usage of a broadly employed
   device identifier be registered with IETF rather than used through
   the organisation device identifier type.

8.  References

8.1.  Normative References

              IEEE, "Guidelines For 64-bit Global Identifier (EUI-64)",
              IEEE  , unknown year,

   [OW]       IEEE, "Overview of 1-Wire(R) Technology and Its Use",
    , June

   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119,
              DOI 10.17487/RFC2119, March 1997,

   [RFC2141]  Moats, R., "URN Syntax", RFC 2141, DOI 10.17487/RFC2141,
              May 1997, <>.

   [RFC2578]  McCloghrie, K., Ed., Perkins, D., Ed., and J.
              Schoenwaelder, Ed., "Structure of Management Information
              Version 2 (SMIv2)", STD 58, RFC 2578,
              DOI 10.17487/RFC2578, April 1999,

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   [RFC3406]  Daigle, L., van Gulik, D., Iannella, R., and P. Faltstrom,
              "Uniform Resource Names (URN) Namespace Definition
              Mechanisms", RFC 3406, DOI 10.17487/RFC3406, October 2002,

   [RFC3986]  Berners-Lee, T., Fielding, R., and L. Masinter, "Uniform
              Resource Identifier (URI): Generic Syntax", STD 66,
              RFC 3986, DOI 10.17487/RFC3986, January 2005,

   [RFC5226]  Narten, T. and H. Alvestrand, "Guidelines for Writing an
              IANA Considerations Section in RFCs", RFC 5226,
              DOI 10.17487/RFC5226, May 2008,

   [RFC5234]  Crocker, D., Ed. and P. Overell, "Augmented BNF for Syntax
              Specifications: ABNF", STD 68, RFC 5234,
              DOI 10.17487/RFC5234, January 2008,

8.2.  Informative References

              Atarius, R., "A Uniform Resource Name Namespace for the
              Device Identity and the Mobile Equipment Identity (MEID)",
              draft-atarius-dispatch-meid-urn-13 (work in progress),
              October 2017.

              Jennings, C., Shelby, Z., Arkko, J., Keranen, A., and C.
              Bormann, "Media Types for Sensor Measurement Lists
              (SenML)", draft-ietf-core-senml-10 (work in progress),
              July 2017.

   [RFC2616]  Fielding, R., Gettys, J., Mogul, J., Frystyk, H.,
              Masinter, L., Leach, P., and T. Berners-Lee, "Hypertext
              Transfer Protocol -- HTTP/1.1", RFC 2616,
              DOI 10.17487/RFC2616, June 1999,

   [RFC3261]  Rosenberg, J., Schulzrinne, H., Camarillo, G., Johnston,
              A., Peterson, J., Sparks, R., Handley, M., and E.
              Schooler, "SIP: Session Initiation Protocol", RFC 3261,
              DOI 10.17487/RFC3261, June 2002,

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   [RFC3971]  Arkko, J., Ed., Kempf, J., Zill, B., and P. Nikander,
              "SEcure Neighbor Discovery (SEND)", RFC 3971,
              DOI 10.17487/RFC3971, March 2005,

   [RFC3972]  Aura, T., "Cryptographically Generated Addresses (CGA)",
              RFC 3972, DOI 10.17487/RFC3972, March 2005,

   [RFC4122]  Leach, P., Mealling, M., and R. Salz, "A Universally
              Unique IDentifier (UUID) URN Namespace", RFC 4122,
              DOI 10.17487/RFC4122, July 2005,

   [RFC4627]  Crockford, D., "The application/json Media Type for
              JavaScript Object Notation (JSON)", RFC 4627,
              DOI 10.17487/RFC4627, July 2006,

   [RFC5612]  Eronen, P. and D. Harrington, "Enterprise Number for
              Documentation Use", RFC 5612, DOI 10.17487/RFC5612, August
              2009, <>.

   [RFC6920]  Farrell, S., Kutscher, D., Dannewitz, C., Ohlman, B.,
              Keranen, A., and P. Hallam-Baker, "Naming Things with
              Hashes", RFC 6920, DOI 10.17487/RFC6920, April 2013,

   [RFC7252]  Shelby, Z., Hartke, K., and C. Bormann, "The Constrained
              Application Protocol (CoAP)", RFC 7252,
              DOI 10.17487/RFC7252, June 2014,

   [RFC7254]  Montemurro, M., Ed., Allen, A., McDonald, D., and P.
              Gosden, "A Uniform Resource Name Namespace for the Global
              System for Mobile Communications Association (GSMA) and
              the International Mobile station Equipment Identity
              (IMEI)", RFC 7254, DOI 10.17487/RFC7254, May 2014,

   [RFC7721]  Cooper, A., Gont, F., and D. Thaler, "Security and Privacy
              Considerations for IPv6 Address Generation Mechanisms",
              RFC 7721, DOI 10.17487/RFC7721, March 2016,

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              Sperberg-McQueen, C., Bray, T., and J. Paoli, "XML 1.0
              Recommendation", World Wide Web Consortium FirstEdition
              REC-xml-19980210, February 1998,

Appendix A.  Changes from Previous Version

   Version -05 made a change to the delimiter for parameters within a
   DEV URN.  Given discussions on allowed character sets in SenML
   [I-D.ietf-core-senml], we would like to suggest that the "_"
   character be used instead of ";", to avoid the need to translate DEV
   URNs in SenML-formatted communications or files.  However, this
   reverses the earlier decision to not use unreserved characters.  This
   also means that device IDs cannot use "_" characters, and have to
   employ other characters instead.  Feedback on this decision is

   Version -05 also introduced local or organisation-specific device
   identifiers.  Organisations are identified by their PEN number
   (although we considered FQDNs as a potential alternative.  The
   authors belive an organisation-specific device identifier type will
   make experiments and local use easier, but feedback on this point and
   the choice of PEN numbers vs. other possible organisation identifiers
   would be very welcome.

   Version -05 also added some discussion of privacy concerns around
   long-term stable identifiers.

   Finally, version -05 clarified the situations when new allocations
   within the registry of possible device identifier subtypes is

   Version -04 is a refresh, as the need and interest for this
   specification has re-emerged.  And the editing author has emerged
   back to actual engineering from the depths of IETF administration.

   Version -02 introduced several changes.  The biggest change is that
   with the NI URNs [RFC6920], it was no longer necessary to define
   cryptographic identifiers in this specification.  Another change was
   that we incorporated a more generic syntax for future extensions;
   non-hexstring identifiers can now also be supported, if some future
   device identifiers for some reason would, for instance, use BASE64.
   As a part of this change, we also changed the component part
   separator character from '-' to ';' so that the general format of the
   rest of the URN can employ the unreserved characters [RFC3986].

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Appendix B.  Acknowledgments

   The authors would like to thank Ari Keranen, Stephen Farrell,
   Christer Holmberg, Peter Saint-Andre, Wouter Cloetens, and Ahmad
   Muhanna for interesting discussions in this problem space.  We would
   also like to note prior documents that focused on specific device
   identifiers, such as [RFC7254] or [I-D.atarius-dispatch-meid-urn].

Authors' Addresses

   Jari Arkko
   Jorvas  02420


   Cullen Jennings
   170 West Tasman Drive
   San Jose, CA  95134

   Phone: +1 408 421-9990

   Zach Shelby
   Kidekuja 2
   Vuokatti  88600

   Phone: +358407796297

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