Internet Engineering Task Force Francis Dupont
INTERNET DRAFT Loutfi Nuaymi
Expires in June 2003 ENST Bretagne
January 2003
IMEI-based universal IPv6 interface IDs
<draft-dupont-ipv6-imei-02.txt>
Status of this Memo
This document is an Internet Draft and is in full conformance with
all provisions of Section 10 of RFC 2026.
This document is an Internet-Draft. Internet-Drafts are working
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Distribution of this memo is unlimited.
Abstract
The IPv6 addressing architecture [1] defines a modified EUI-64
format for interface identifiers. These interface identifiers may
have global scope when a global token is available (e.g., IEEE 802
48-bit MAC or IEEE EUI-64 identifiers). Such a global token, the
IMEI (International Mobile station Equipment Identity), is defined
for GSM and UMTS terminals [2, 3, 4] and has the same properties
than identifiers based on IEEE standards.
This document explains the construction of a global IPv6 interface
identifier from an IMEI.
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1. Modified EUI-64 Interface Identifiers
The modified EUI-64 format is required for all unicast addresses,
except those that start with binary value 000. Two bits have a
special role in IEEE EUI-64 and in modified EUI-64: the "u" bit,
one means global scope, zero local scope, and the "g" bit which
is the "individual/group" in IEEE standards and is always set to
zero for any modified EUI-64 identifier derived from an IEEE 802
identifier.
So when both the "u" and "g" bits are set to one, a modified EUI-64
identifier has a global scope (i.e. is universal) and is not
derived from an IEEE identifier.
2. IMEIs
The IMEI (International Mobile station Equipment Identities) is 14
decimal digit number attached to the hardware of any GSM [2, 3]
or UMTS [4] terminal. It is usually written on a label in the
battery compartment of the handset or displayed when dialing the
code *#06# (it can come with a spare digit and/or the software
version number), etc. The Mobile Station Equipment is uniquely
defined by the IMEI.
The EIR (Equipment Identity Register) is the database of all
IMEIs, it can be used in order to block or trace stolen terminals
even only some operators currently check IMEIs.
The IMEI is divided into a Type Approval Code (which begins by
a country code) on 6 decimal digits followed by a Final Assembly
Code on 2 decimal digits and the Serial Number on 6 decimal
digits. The IMEI has the same properties than an IEEE MAC-48
address, it is attached to the hardware and reveals only basic
information like the producer and the model of the hardware
(this is not always true for ESN (Electronic Serial Numbers)
which are used in some USA mobile phone networks).
IMEIs are globally unique, two different equipments can be
assumed to have different IMEIs and when this is not true
(manufacturer error, hardware problem, cloning) the problem can
cause damage at a higher level than interface identifier
collision, exactly as a MAC address collision is a very serous
incident which has nothing in common with an interface identifier
collision.
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3. IMEI-based Interface Identifiers
This document defines a method to create an interface identifier
in the modified EUI-64 format from an IMEI. The first octet is 03
in hexadecimal ("u" and "g" bits set to one, others to zero)
followed by the 14 decimal digits of the IMEI in BCD (Binary
Coded Decimal), i.e. with each decimal digit mapped to its value
on 4 bits.
The IMEI 330001 53 007826 gives the 0333:0001:5300:7826 (usually
written 333:1:5300:7826) interface identifier.
4. Security Considerations
The security considerations of IMEI-based interface identifiers
are exactly the same than for IEEE EUI-64, EUI-48 or MAC-48
based interface identifiers. The concerns about traceability
and/or privacy are addressed in [5].
The IMEI is supposedly used to report stolen terminals to telecom
operators. It seems common sense that these operators are to
perform some additional owner's identity verification before
accepting such kind of report. Somebody capable of intercepting
the IMEI of a terminal cannot easily report it as stolen.
5. Acknowledgments
The idea came during an E-mail exchange about Marcelo Bagnulo's
draft [6] on random generation of interface identifiers.
Our GSM expert, Xavier Lagrange, provides in some seconds all the
GSM and 3GPP references and the (real) IMEI of the example.
The same idea was developped in the EU project "Moby Dick" [7]
(signaled by Michelle Wetterwald).
6. Normative References
[1] R. Hinden, S. Deering, "IP Version 6 Addressing Architecture",
draft-ietf-ipngwg-addr-arch-v3-11.txt (update of RFC 2373),
October 2002.
[2] "Digital cellular telecommunications system: Numbering,
addressing and identification", ETS 300 927 aka GSM 03.03,
ETSI, November 1999.
[3] "Digital cellular telecommunications system: International
Mobile station Equipment Identities (IMEI)", GSM 02.16,
ETSI, February 2000.
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[4] "3rd Generation Partnership Project: Technical Specification
Group Core Network; Numbering, addressing and identification
(Release 1999)", 3GPP TS 23.003, 3GPP, June 2001.
[5] T. Narten, R. Draves, "Privacy Extensions for Stateless Address
Autoconfiguration in IPv6", RFC 3041, January 2001.
7. Informative References
[6] M. Bagnulo, I. Soto, A. Garcia-Martinez, A. Azcorra,
"Random generation of interface identifiers",
draft-soto-mobileip-random-iids-00.txt, January 2002.
[7] M. Liebsch, X. Perez, R. Schmitz, A. Sarma, J. Jaehnert,
S. Tessier, M. Wetterwald, I. Soto, "Solutions for IPv6-based
mobility in the EU project Moby Dick", WTC 2002, Paris,
22-27 September 2002.
8. Changes from Previous Drafts
The Security Considerations section was updated to answer to a
concern raised at the 53th IETF at Minneapolis in March 2002.
A reference to a conference paper which includes this idea was
added in the Informative References section.
9. Authors' Addresses
Francis Dupont
ENST Bretagne
Campus de Rennes
2, rue de la Chataigneraie
BP 78
35512 Cesson-Sevigne Cedex
FRANCE
Fax: +33 2 99 12 70 30
EMail: Francis.Dupont@enst-bretagne.fr
Loutfi Nuaymi
ENST Bretagne
Campus de Rennes
2, rue de la Chataigneraie
BP 78
35512 Cesson-Sevigne Cedex
FRANCE
Fax: +33 2 99 12 70 30
EMail: Loutfi.Nuaymi@enst-bretagne.fr
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