1、 INTERNATIONAL TELECOMMUNICATION UNION ITU-T X.667TELECOMMUNICATION STANDARDIZATION SECTOR OF ITU (10/2012) SERIES X: DATA NETWORKS, OPEN SYSTEM COMMUNICATIONS AND SECURITY OSI networking and system aspects Naming, Addressing and Registration Information technology Procedures for the operation of ob
2、ject identifier registration authorities: Generation of Universally Unique Identifiers (UUIDs) and their use in object identifiers CAUTION ! PREPUBLISHED RECOMMENDATION This prepublication is an unedited version of a recently approved Recommendation. It will be replaced by the published version afte
3、r editing. Therefore, there will be differences between this prepublication and the published version. FOREWORD The International Telecommunication Union (ITU) is the United Nations specialized agency in the field of telecommunications, information and communication technologies (ICTs). The ITU Tele
4、communication Standardization Sector (ITU-T) is a permanent organ of ITU. ITU-T is responsible for studying technical, operating and tariff questions and issuing Recommendations on them with a view to standardizing telecommunications on a worldwide basis. The World Telecommunication Standardization
5、Assembly (WTSA), which meets every four years, establishes the topics for study by the ITU-T study groups which, in turn, produce Recommendations on these topics. The approval of ITU-T Recommendations is covered by the procedure laid down in WTSA Resolution 1. In some areas of information technology
6、 which fall within ITU-Ts purview, the necessary standards are prepared on a collaborative basis with ISO and IEC. NOTE In this Recommendation, the expression “Administration“ is used for conciseness to indicate both a telecommunication administration and a recognized operating agency. Compliance wi
7、th this Recommendation is voluntary. However, the Recommendation may contain certain mandatory provisions (to ensure, e.g., interoperability or applicability) and compliance with the Recommendation is achieved when all of these mandatory provisions are met. The words “shall“ or some other obligatory
8、 language such as “must“ and the negative equivalents are used to express requirements. The use of such words does not suggest that compliance with the Recommendation is required of any party. INTELLECTUAL PROPERTY RIGHTS ITU draws attention to the possibility that the practice or implementation of
9、this Recommendation may involve the use of a claimed Intellectual Property Right. ITU takes no position concerning the evidence, validity or applicability of claimed Intellectual Property Rights, whether asserted by ITU members or others outside of the Recommendation development process. As of the d
10、ate of approval of this Recommendation, ITU had/had not received notice of intellectual property, protected by patents, which may be required to implement this Recommendation. However, implementers are cautioned that this may not represent the latest information and are therefore strongly urged to c
11、onsult the TSB patent database at http:/www.itu.int/ITU-T/ipr/. ITU 2013 All rights reserved. No part of this publication may be reproduced, by any means whatsoever, without the prior written permission of ITU. Rec. ITU-T X.667 (10/2012) Prepublished version 1 INTERNATIONAL STANDARD ISO/IEC 9834-8 R
12、ECOMMENDATION ITU-T X.667 Information technology Procedures for the operation of object identifier registration authorities: Generation of Universally Unique Identifiers (UUIDs) and their use in object identifiers Summary Recommendation ITU-T X.667 | ISO/IEC 9834-8 specifies procedures for the gener
13、ation of UUIDs and for their use in the international object identifier tree under the joint UUID arc. Source Recommendation ITU-T X.667 was approved on 27 February 2013 by ITU-T Study Group 17 under Recommendation ITU-T A.8 procedure. An identical text is also published as ISO/IEC 9834-8. Rec. ITU-
14、T X.667 (10/2012) Prepublished version 2 CONTENTS Page 1 Scope 1 2 Normative references 1 2.1 Identical Recommendations | International Standards . 1 2.2 Other normative references 1 3 Terms and definitions . 2 3.1 ASN.1 notation . 2 3.2 Registration authorities . 2 3.3 Network terms 2 3.4 Additiona
15、l definitions . 2 4 Abbreviations 3 5 Notation 3 6 UUID structure and representation . 3 6.1 UUID field structure . 3 6.2 Binary representation 4 6.3 Representation as a single integer value . 4 6.4 Hexadecimal representation . 4 6.5 Formal syntax of the hexadecimal representation 4 7 Use of a UUID
16、as the primary integer value and Unicode label of a Joint UUID arc . 5 8 Use of a UUID to form a URN . 5 9 Rules for comparison and ordering of UUIDs 5 10 Validation . 6 11 Variant bits . 6 12 Use of UUID fields and transmission byte order 6 12.1 General . 6 12.2 Version . 7 12.3 Time 7 12.4 Clock s
17、equence . 8 12.5 Node . 8 13 Setting the fields of a time-based UUID. 9 14 Setting the fields of a name-based UUID . 9 15 Setting the fields of a random-number-based UUID 10 Rec. ITU-T X.667 (10/2012) Prepublished version 3 Annex A Algorithms for the efficient generation of time-based UUIDs 13 A.1 B
18、asic algorithm . 13 A.2 Reading stable storage 13 A.3 System clock resolution 13 A.4 Writing stable storage . 14 A.5 Sharing state across processes 14 Annex B Properties of name-based UUIDs 15 Annex C Generation of random numbers in a system 16 Annex D Sample implementation . 17 D.1 Files provided .
19、 17 D.2 The copyrt.h file . 17 D.3 The uuid.h file 17 D.4 The uuid.c file 18 D.5 The sysdep.h file . 21 D.6 The sysdep.c file . 21 D.7 The utest.c file 23 D.8 Sample output of utest 23 D.9 Some name space IDs . 24 Bibliography. 25 Rec. ITU-T X.667 (10/2012) Prepublished version 4 Introduction This R
20、ecommendation | International Standard standardizes the generation of universally unique identifiers (UUIDs). UUIDs are an octet string of 16 octets (128 bits). The 16 octets can be interpreted as an unsigned integer encoding, and the resulting integer value can be used as the primary integer value
21、(defining an integer-valued Unicode label) for an arc of the International Object Identifier tree under the Joint UUID arc. This enables users to generate object identifier and OID internationalized resource identifier names without any registration procedure. UUIDs are also known as globally unique
22、 identifiers (GUIDs), but this term is not used in this Recommendation | International Standard. UUIDs were originally used in the network computing system (NCS) 1 and later in the Open Software Foundations Distributed Computing Environment (DCE) 2. ISO/IEC 11578 3 contains a short definition of som
23、e (but not all) of the UUID formats specified in this Recommendation | International Standard. The specification in this Recommendation | International Standard is consistent with all these earlier specifications. UUIDs forming a component of an OID are represented in ASN.1 value notation as the dec
24、imal representation of their integer value, but for all other display purposes it is more usual to represent them with hexadecimal digits with a hyphen separating the different fields within the 16-octet UUID. This representation is defined in this Recommendation | International Standard. If generat
25、ed according to one of the mechanisms defined in this Recommendation | International Standard, a UUID is either guaranteed to be different from all other UUIDs generated before 3603 A.D., or is extremely likely to be different (depending on the mechanism chosen). No centralized authority is required
26、 to administer UUIDs. Centrally generated UUIDs are guaranteed to be different from all other UUIDs centrally generated. A UUID can be used for multiple purposes, from tagging objects with an extremely short lifetime, to reliably identifying very persistent objects across a network, particularly (bu
27、t not necessarily) as part of an object identifier or OID internationalized resource identifier value, or in a uniform resource name (URN). The UUID generation algorithm specified in this Recommendation | International Standard supports very high allocation rates: 10 million per second per machine i
28、f necessary, so UUIDs can also be used as transaction IDs. An informative annex provides a program in the C language that will generate UUIDs in accordance with this Recommendation | International Standard. Three algorithms are specified for the generation of unique UUIDs, using different mechanisms
29、 to ensure uniqueness. These produce different versions of a UUID. The first (and most common) mechanism produces the so-called time-based version. These UUIDs can be generated at the rate of 10 million per second. For UUIDs generated within a single computer system, a 60-bit time-stamp (used as a C
30、lock value) with a granularity of 100 nanoseconds, based on coordinated universal time (UTC) is used to guarantee uniqueness over a period of approximately 1600 years. For UUIDs generated with the same time-stamp by different systems, uniqueness is obtained by use of 48-bit media access control (MAC
31、) addresses, specified in ISO/IEC 8802-3 (this is used as a Node value). (These addresses are usually already available on most networked systems, but are otherwise obtainable from the IEEE Registration Authority for MAC addresses see 4.) Alternative ways of generating Clock and Node values are spec
32、ified for the time-based version if UTC time is not available on a system, or if there is no MAC address available. The second mechanism produces a single UUID that is a name-based version, where cryptographic hashing is used to produce the 128-bit UUID value from a globally unambiguous (text) name.
33、 Rec. ITU-T X.667 (10/2012) Prepublished version 5 The third mechanism uses pseudo-random or truly random number generation to produce most of the bits in the 128-bit value. Clause 5 specifies the notation used for octet-order and bit-order naming, and for specification of transmission order. Clause
34、 6 specifies the structure of a UUID and the representation of it in binary, hexadecimal, or as a single integer value. Clauses 7 and 8 specify the use of a UUID in an OID or a URN respectively. Clause 9 specifies rules for comparing UUIDs to test for equality or to provide an ordering relation betw
35、een two UUIDs. Clause 10 discusses the possibility of checking the validity of a UUID. In general, UUIDs have little redundancy, and there is little scope for checking their validity. Clause 11 describes the historical use of some bits in the UUID to define different variants of the UUID format, and
36、 specifies the value of these bits for UUIDs defined in accordance with this Recommendation | International Standard. Clause 12 specifies the use of the fields of a UUID in the different versions that are defined (time-based, name-based, and random-number based versions). It also defines the transmi
37、ssion byte order. Clause 13 specifies the setting of the fields of a time-based UUID. Clause 14 specifies the setting of the fields of a name-based UUID. Clause 15 specifies the setting of the fields of a random-number-based UUID. All annexes are informative. Annex A describes various algorithms for
38、 the efficient generation of time-based UUIDs. Annex B discusses the properties that a name-based UUID should have, affecting the selection of name spaces for use in generating such UUIDs. Annex C provides guidance on mechanisms that can be used to generate random numbers in a computer system. Annex
39、 D contains a complete program in the C programming language that can be used to generate UUIDs. ISO/IEC 9834-8 :2013 Rec. ITU-T X.667 (10/2012) Prepublished version 6 INTERNATIONAL STANDARD ISO/IEC 9834-8 RECOMMENDATION ITU-T X.667 Information technology Procedures for the operation of object ident
40、ifier registration authorities: Generation of Universally Unique Identifiers (UUIDs) and their use in object identifiers 1 Scope This Recommendation | International Standard specifies the format and generation rules that enable users to produce 128-bit identifiers that are either guaranteed to be gl
41、obally unique, or are globally unique with a high probability. The UUIDs generated in conformance with this Recommendation | International Standard are suitable either for transient use, with generation of a new UUID every 100 nanoseconds, or as persistent identifiers. This Recommendation | Internat
42、ional Standard is derived from earlier non-standard specifications of UUIDs and their generation, and is technically identical to those earlier specifications. This Recommendation | International Standard also specifies and allows the use of UUIDs as primary values (which define Unicode labels) for
43、arcs beneath the Joint UUID arc. This enables users to generate and use such arcs without any registration procedures. This Recommendation | International Standard also specifies and allows the use of UUIDs to form a URN. 2 Normative references The following Recommendations and International Standar
44、ds contain provisions which, through reference in this text, constitute provisions of this Recommendation | International Standard. At the time of publication, the editions indicated were valid. All Recommendations and Standards are subject to revision, and parties to agreements based on this Recomm
45、endation | International Standard are encouraged to investigate the possibility of applying the most recent edition of the Recommendations and Standards listed below. Members of IEC and ISO maintain registers of currently valid International Standards. The Telecommunication Standardization Bureau of
46、 the ITU maintains a list of currently valid ITU-T Recommendations. 2.1 Identical Recommendations | International Standards Recommendation ITU-T X.660 (2011) | ISO/IEC 9834-1:2011, Information technology Procedures for the operation of object identifier registration authorities: General procedures a
47、nd top arcs of the international object identifier tree. Recommendation ITU-T X.680 (2008) | ISO/IEC 8824-1:2008, Information technology Abstract Syntax Notation One (ASN.1): Specification of basic notation. 2.2 Other normative references ISO/IEC 8802-3:2000, Information technology Telecommunication
48、s and information exchange between systems Local and metropolitan area networks Specific requirements Part 3: Carrier sense multiple access with collision detection (CSMA/CD) access method and physical layer specifications. ISO/IEC 10118-3:2004, Information technology Security techniques Hash functi
49、ons Part 3: Dedicated hash-functions. ISO/IEC 9834-8 :2013 Rec. ITU-T X.667 (10/2012) Prepublished version 7 ISO/IEC 10646:2012, Information technology Universal Multiple-Octet Coded Character Set (UCS). FIPS PUB 180-3:2008, Federal Information Processing Standards Publication, Secure Hash Standard (SHS). IETF RFC 1321 (1992), The MD5 Message-Digest Algorithm. IETF RFC 2141 (1997), URN Syntax. 3 Terms and definitions For the purposes of this Recommendation | International Standard, the foll
