Network Working Group M. Montemurro, Ed.
Internet-Draft A. Allen
Intended status: Informational Research in Motion (RIM)
Expires: October 2, 2009 D. McDonald
unaffiliated
P. Gosden
GSM Association
March 31, 2009
A Uniform Resource Name Namespace For The GSM Association (GSMA) and the
International Mobile station Equipment Identity(IMEI)
draft-montemurro-gsma-imei-urn-04
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Abstract
This specification defines a Uniform Resource Name namespace for the
GSMA and sub namespaces for the IMEI (International Mobile station
Equipment Identity), and for the IMEISV (International Mobile station
Equipment Identity and Software Version number). The IMEI is 15
decimal digits long and the IMEISV is 16 decimal digits long and both
are encoded using Binary Encoded Decimal (BCD). The IMEI and IMEISV
were introduced as part of the specification for Global System for
Mobile (GSM) and are also now incorporated by the 3rd Generation
Partnership Project (3GPP) as part of the 3GPP specification for GSM,
and the Universal Mobile Telecommunications System (UMTS). The IMEI
and IMEISV are used to uniquely identify Mobile Equipment within
these systems and are managed by the GSMA (GSM Association).
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 4
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 5
3. Namespace Registration Template . . . . . . . . . . . . . . . 5
3.1. GSMA . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
4. Specification . . . . . . . . . . . . . . . . . . . . . . . . 8
4.1. IMEI Format . . . . . . . . . . . . . . . . . . . . . . . 8
4.1.1. Type Allocation Code (TAC) . . . . . . . . . . . . . . 9
4.1.2. Serial Number (SNR) . . . . . . . . . . . . . . . . . 9
4.1.3. Spare . . . . . . . . . . . . . . . . . . . . . . . . 9
4.2. IMEISV Format . . . . . . . . . . . . . . . . . . . . . . 9
4.2.1. Type Allocation Code (TAC) . . . . . . . . . . . . . . 10
4.2.2. Serial Number (SNR) . . . . . . . . . . . . . . . . . 10
4.2.3. Software Version Number (SVN) . . . . . . . . . . . . 10
5. Community considerations . . . . . . . . . . . . . . . . . . . 10
6. Use as an Instance ID . . . . . . . . . . . . . . . . . . . . 10
7. Namespace considerations . . . . . . . . . . . . . . . . . . . 10
8. IANA considerations . . . . . . . . . . . . . . . . . . . . . 11
9. Security considerations . . . . . . . . . . . . . . . . . . . 11
10. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 11
11. References . . . . . . . . . . . . . . . . . . . . . . . . . . 11
11.1. Normative references . . . . . . . . . . . . . . . . . . . 11
11.2. Informative references . . . . . . . . . . . . . . . . . . 12
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 12
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1. Introduction
This specification defines a Uniform Resource Name namespace for the
GSMA (GSM Association) and sub namespaces for the IMEI (International
Mobile station Equipment Identity), and for the IMEISV (International
Mobile station Equipment Identity and Software Version number as per
the namespace registration requirement found in [1]. GSMA is an
identifier for a namespace for identities used by Mobile Equipment
used in GSM and UMTS networks. The IMEI and the IMEISV are managed
by the GSMA, so this namespace would be managed by the GSMA. Whilst
this specification currently specifies only the IMEI and IMEISV sub
namespaces under the GSMA URN namespace additional sub namespaces
under the GSMA namespace may be specified in the future by the GSMA
through the publication of future informational RFCs.
The IMEI is 15 decimal digits long and includes a Type Allocation
Code (TAC) of 8 decimal digits and the Serial Number (SNR) of 6
decimal digits plus a Spare decimal digit. The TAC identifies the
type of the Mobile Equipment and is chosen from a range of values
allocated to the Mobile Equipment manufacturer in order to uniquely
identify the model of the Mobile Equipment. The SNR is an individual
serial number that uniquely identifies each Mobile Equipment within
the TAC. The Spare digit is used as a security check to combat
potential spoofing and is always set to the value 0 when transmitted
by the Mobile Equipment.
The IMEISV is 16 decimal digits long and includes the TAC and SNR
same as for the IMEI but also a 2 decimal digit Software Version
Number (SVN) which is allocated by the Mobile Equipment manufacturer
to identify the software version of the Mobile Equipment.
The IMEI is specified to be stored in a tamper proof fashion so that
it cannot be overwritten or otherwise reprogrammed by software.
The information here is meant to be a concise guide for those wishing
to use the IMEI and IMEISV as URNs. Nothing in this document should
be construed to override 3GPP TS 23.003 [2] that defines the IMEI and
IMEISV.
The GSM Association (GSMA) is a global trade association representing
more than 750 GSM mobile phone operators across 218 territories and
countries of the world. The primary goals of the GSMA are to ensure
mobile phones and wireless services work globally and are easily
accessible. Further details about the GSMA role in allocating the
IMEI and the IMEISV and the IMEI and IMEISV allocation guidelines can
be found in GSMA PRD DG.06 [3]
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2. 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 [4].
3. Namespace Registration Template
3.1. GSMA
Namespace ID: "gsma" requested
Registration Information:
Registration version number: 1
Registration date: 2006-10-11
Declared registrant of the namespace: GSM Association, 1st Floor,
Mid City Place, 71 High Holborn, London, England
Declaration of syntactic structure:
The identifier is expressed in ASCII (UTF-8) characters and has a
hierarchical structure as follows:
urn:gsma:<gsma-specifier>[:<gsma-specifier-defined-string>]+
where
<gsma-specifier> = "imei" | "imeisv"
<gsma-specifier-defined-string> = GSMA-approved string
+ = one or more occurences of "gsma-specifier-defined-string"
The GSMA namespace includes two predefined namespaces IMEI and
IMEISV and may be in the future extended to include other
identifiers used by Mobile Equipment used in GSM and UMTS networks
or future networks deployed by members of the GSMA.
A IMEI is an identifier under the GSMA namespace that uniquely
identifies Mobile Equipment used in GSM and UMTS networks.
The internal representation of a IMEI is a specific sequence of
bits in memory, as described in 3GPP TS 23.003 [2]. To accurately
represent a IMEI as a URN, it is necessary to convert the BCD bit
sequence to a string representation. Each field BCD bit sequence
has its value printed as a decimal digit string with the most
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significant digit first.
The following augmented Backus-Naur Form (ABNF) includes the set
of core rules in RFC 5234 [8], and are not repeated here.
The formal definition of the IMEI string representation is
provided by the following ABNF [8]:
IMEI = tac "-" snr "-" spare
tac = 8DIGIT
snr = 6DIGIT
spare = 1DIGIT
For example:
urn:gsma:imei:90420156-025763-0
A IMEISV is an identifier under the GSMA namespace that uniquely
identifies Mobile Equipment and associated software versions used
in GSM and UMTS networks. The internal representation of a IMEISV
is a specific sequence of bits in memory, as described in 3GPP TS
23.003 [2]. To accurately represent a IMEISV as a URN, it is
necessary to convert the BCD bit sequence to a string
representation. Each field BCD bit sequence has its value printed
as a decimal digit string with the most significant digit first.
The formal definition of the IMEISV string representation is
provided by the following ABNF [8]:
IMEISV = tac "-" snr "-" svn
tac = 8DIGIT
snr = 6DIGIT
svn = 2DIGIT
For example:
urn:gsma:imeisv:90420156-025763-42
The <gsma-specifier> and <gsma-specifier defined string> can
comprise any ASCII characters compliant with URI syntax and must
not contain the ":" character (see STD 66, RFC 3986 [5]). The
exclusion of the colon from the list of other characters means
that the colon can only occur as a delimiter between string
values.
The GSMA will take responsibility for the gsma-specifier "imei"
and "imeisv" and manage the sub level.
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Additional gsma-specifiers may be added in the future through
informational RFCs.
Relevant ancillary documentation:
See IMEI Allocation and Approval Guidelines [3] and 3GPP TS 23.003
[2].
Identifier uniqueness considerations:
Identifiers in the "gsma" namespace are defined and assigned in
the requested namespace by the GSMA after ensuring that the URNs
to be assigned are unique. Uniqueness is achieved by checking
against the registry of previously assigned names.
Procedures are in place to ensure that each IMEI is uniquely
assigned by the Mobile Equipment manufacturer so that it is
guaranteed to uniquely identify that particular Mobile Equipment.
IMEIs are stored in the Mobile Equipment in a tamper proof non
modifiable fashion so they remain persistent.
Procedures are in place to ensure that each IMEISV is uniquely
assigned by the Mobile Equipment manufacturer so that it is
guaranteed to uniquely identify that particular Mobile Equipment
and the specific software version installed.
Identifier persistence considerations:
The GSMA is committed to maintaining uniqueness and persistence of
all resources identified by assigned URNs.
As the NID sought is "gsma" and GSMA is the long standing acronym
for the trade association that represents the mobile phone
operators the URN should also persist indefinitely (at least as
long as there is a need for its use). The assignment process
guarantees that names are not reassigned. The binding between the
name and its resource is permanent.
IMEIs are stored in Mobile Equipment in a tamper proof non-
modifiable fashion so they remain persistent
The TAC and SNR portions of IMEISVs are stored in the Mobile
Equipment in a tamper proof non modifiable fashion so they remain
persistent. The SVN may be modified by software when new versions
are installed but should be persistent for the duration of the
installation of that specific version of software.
Process of identifier assignment:
GSMA will manage the <gsma-specifier> and <gsma-defined string>
including "imei" and "imeisv" identifier resources to maintain
uniqueness.
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The process for IMEI and IMEISV assignment is documented in GSMA
PRD DG.06[3]
Process for identifier resolution:
Since the GSMA namespace is not globally resolvable, this is not
applicable.
Rules for Lexical Equivalence:
Consider each field of the IMEI or IMEISV to be a sequence of
decimial digits. Then, to compare a pair of IMEIs or IMEISVs,
arithmetically compare the corresponding fields from each IMEI or
IMEISV in order of significance and according to their data type.
Two IMEIs or IMEISVs are equal if and only if all the
corresponding fields are equal.
The lexical equivalence of the GSMA namespace-specific strings
(NSSs) is defined as an exact, but not case-sensitive, string
match.
Any identifier in GSMA namespaces can be compared using the normal
mechanisms for percent-encoded UTF-8 strings.
Conformance with URN Syntax:
The string representation of the GSMA URN and of the IMEI and
IMEISV subnamespaces is fully compatible with the URN syntax.
Validation Mechanism:
The IMEI can be validated using the mechanism defined in Annex B
of 3GPP TS 23.003 [2]. The TAC and SNR fields of the IMEISV can
be validated using the mechanism defined in Annex B of 3GPP TS
23.003 [2]. There is no mechanism defined to validate the SVN
field of the IMEISV.
Scope: GSMA URN is global in scope.
4. Specification
4.1. IMEI Format
The IMEI format is 15 decimal digits encoded in 8 octets using BCD as
defined in 3GPP TS 24.008 [6]. The most significant digit is coded
in the most significant bits of octet 1. The least significant digit
is coded in the least significant bits of octet 8.
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14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 Decimal Digits
+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
| | | S|
| T | S | p|
| A | N | a|
| C | R | r|
| | | e|
+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
1 2 3 4 5 6 7 8 Octets
4.1.1. Type Allocation Code (TAC)
The TAC is a 8 decimal digit value. The TAC identifies the type of
the Mobile Equipment and is chosen from a range of values allocated
to the Mobile Equipment manufacturer in order to uniquely identify
the model of the Mobile Equipment.
4.1.2. Serial Number (SNR)
The SNR is a 6 decimal digit value. The SNR is an individual serial
number that uniquely identifies each Mobile Equipment within the TAC.
4.1.3. Spare
The Spare is a single decimal digit that is used as a security check
digit to combat potential spoofing. The Spare is always set to zero
when transmitted by the Mobile Equipment. Annex B of 3GPP TS 23.003
[2] defines a mechanism for computing the actual check digit in order
to validate the TAC and SNR.
4.2. IMEISV Format
The IMEISV format is 16 decimal digits encoded in 8 octets using BCD
as defined in 3GPP TS 24.008 [6]. The most significant digit is
coded in the most significant bits of octet 1. The least significant
digit is coded in the least significant bits of octet 8.
15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 Decimal Digits
+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
| | | |
| T | S | S |
| A | N | V |
| C | R | N |
| | | |
+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
1 2 3 4 5 6 7 8 Octets
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4.2.1. Type Allocation Code (TAC)
The TAC is the same as for the IMEI in Section 5.1.1.
4.2.2. Serial Number (SNR)
The SNR is the same as for the IMEI in Section 5.1.2.
4.2.3. Software Version Number (SVN)
The Software Version Number is allocated by the Mobile Equipment
manufacturer to identify the software version of the Mobile
Equipment.
5. Community considerations
GSM and UMTS mobile devices will be interoperating with Internet
devices for a variety of voice and data services. To do this, they
need to make use of Internet protocols that will operate end to end
between devices in GSM/UMTS networks and those in the general
internet. Many of these protocols require the use of URN's as
identifiers. Within the GSM/UMTS networks, mobile devices are
identified by their IMEI and IMEISV. Internet users will need to be
able to receive and include the GSMA URN in various Internet protocol
elements to facilitate communication between pure internet based
devices and GSM and UMTS mobile devices. Thus the existence and
syntax of these namespaces needs to be available to the general
internet community and the namespace needs to be reserved with IANA
in order to guarantee uniqueness and prevent potential namespace
conflicts both within the internet and within GSM/UMTS networks.
6. Use as an Instance ID
The IMEI and IMEISV URNs MAY be used as an Instance ID and included
in the sip.instance parameter of a Contact header field of a SIP
Register request as specified in draft-ietf-sip-outbound [9].
7. Namespace considerations
A URN was considered the most appropriate URI to represent the IMEI
and IMEISV as these identifiers may be used and transported similarly
to the Universally Unique Identifier (UUID)which is defined as a URN
in [10]. Since specifications for protocols that are used to
transport device identifiers often require the device identifier to
be globally unique and in the URN format it is necessary that the
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IMEI and IMEISV URN formats are defined.
8. IANA considerations
In accordance with BCP 66 [1], IANA is asked to register the Formal
URN Namespace 'GSMA' in the Registry of URN Namespaces, using the
registration template presented in Section 3 of this document.
9. Security considerations
IMEIs (with the Spare value set to zero) are displayable on most
Mobile Equipment; therefore, they must not be used as security
capabilities (identifiers whose mere possession grants access), for
example.
Revealing the specific software version of the terminal might make
the terminal more vulnerable to attacks against software that is
known to contain security holes. This is a similar concern to the
use of the User-Agent header in SIP as specified in RFC 3261 [11].
It is therefore RECOMMENDED that the IMEISV is not delivered to
devices that are not trusted. Care should be taken regarding use of
the IMEISV as it could help a malicious device identify Mobile
Equipment running software that is known to be vulnerable to certain
attacks.
Additional security considerations are specified in 3GPP TS 22.016
[7]. Specifically the IMEI is to be incorporated in a module which
is contained within the terminal. The IMEI SHALL not be changed
after the terminal's production process. It SHALL resist tampering,
i.e. manipulation and change, by any means (e.g. physical, electrical
and software).
10. Acknowledgements
This document draws heavily on the 3GPP work on Numbering, Addressing
and Identification in 3GPP TS 23.003 [2] and also on the style and
structure used in RFC 4122 [10].
11. References
11.1. Normative references
[1] Daigle, L., van Gulik, D., Iannella, R., and P. Faltstrom,
"Uniform Resource Names (URN) Namespace Definition Mechanisms",
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BCP 66, RFC 3406, October 2002.
[2] 3GPP, "TS 23.003: Numbering, addressing and identification
(Release 8)", 3GPP 23.003, September 2008,
<ftp://ftp.3gpp.org/Specs/archive/23_series/23.003/>.
[3] GSMA Association, "IMEI Allocation and Approval Guidelines",
PRD DG.06 version 3.6, February 2008,
<http://www.gsmworld.com/documents/twg/dg06_3v6.pdf>.
[4] Bradner, S., "Key words for use in RFCs to Indicate Requirement
Levels", BCP 14, RFC 2119, March 1997.
[5] Berners-Lee, T., Fielding, R., and L. Masinter, "Uniform
Resource Identifier (URI): Generic Syntax", STD 66, RFC 3986,
January 2005.
[6] 3GPP, "TS 24.008: Mobile radio interface Layer 3 specification;
Core network protocols; Stage 3 (Release 8)", 3GPP 24.008,
September 2008,
<ftp://ftp.3gpp.org/Specs/archive/24_series/24.008/>.
[7] 3GPP, "TS 22.016: International Mobile station Equipment
Identities (IMEI)(Release 7)", 3GPP 22.016, May 2007,
<ftp://ftp.3gpp.org/Specs/archive/22_series/22.016/>.
11.2. Informative references
[8] Crocker, D. and P. Overell, "Augmented BNF for Syntax
Specifications: ABNF", STD 68, RFC 5234, January 2008.
[9] Jennings, C. and R. Mahy, "Managing Client Initiated
Connections in the Session Initiation Protocol (SIP)",
draft-ietf-sip-outbound-16 (work in progress), October 2008.
[10] Leach, P., Mealling, M., and R. Salz, "A Universally Unique
IDentifier (UUID) URN Namespace", RFC 4122, July 2005.
[11] Rosenberg, J., Schulzrinne, H., Camarillo, G., Johnston, A.,
Peterson, J., Sparks, R., Handley, M., and E. Schooler, "SIP:
Session Initiation Protocol", RFC 3261, June 2002.
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Authors' Addresses
Michael Montemurro (editor)
Research in Motion (RIM)
4701 Tahoe Dr
Mississauga, Ontario L4W 0B4
Canada
Phone: unlisted
Fax: unlisted
Email: mmontemurro@rim.com
Andrew Allen
Research in Motion (RIM)
300 Knightsbridge Parkway, Suite 360
Lincolnshire, Illinois 60069
USA
Phone: unlisted
Fax: unlisted
Email: aallen@rim.com
David McDonald
unaffiliated
Phone: unlisted
Fax: unlisted
Email: mcdonalddm@hotmail.com
Paul Gosden
GSM Association
1st Floor, Mid City Place, 71 High Holborn,
London
England
Phone: unlisted
Fax: unlisted
Email: pgosden@gsm.org
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