1、 I n t e r n a t i o n a l T e l e c o m m u n i c a t i o n U n i o n ITU-T X.695 TELECOMMUNICATION STANDARDIZATION SECTOR OF ITU (08/2015) SERIES X: DATA NETWORKS, OPEN SYSTEM COMMUNICATIONS AND SECURITY OSI networking and system aspects Abstract Syntax Notation One (ASN.1) Information technology
2、ASN.1 encoding rules: Registration and application of PER encoding instructions Recommendation ITU-T X.695 ITU-T X-SERIES RECOMMENDATIONS DATA NETWORKS, OPEN SYSTEM COMMUNICATIONS AND SECURITY PUBLIC DATA NETWORKS Services and facilities X.1X.19 Interfaces X.20X.49 Transmission, signalling and switc
3、hing X.50X.89 Network aspects X.90X.149 Maintenance X.150X.179 Administrative arrangements X.180X.199 OPEN SYSTEMS INTERCONNECTION Model and notation X.200X.209 Service definitions X.210X.219 Connection-mode protocol specifications X.220X.229 Connectionless-mode protocol specifications X.230X.239 PI
4、CS proformas X.240X.259 Protocol Identification X.260X.269 Security Protocols X.270X.279 Layer Managed Objects X.280X.289 Conformance testing X.290X.299 INTERWORKING BETWEEN NETWORKS General X.300X.349 Satellite data transmission systems X.350X.369 IP-based networks X.370X.379 MESSAGE HANDLING SYSTE
5、MS X.400X.499 DIRECTORY X.500X.599 OSI NETWORKING AND SYSTEM ASPECTS Networking X.600X.629 Efficiency X.630X.639 Quality of service X.640X.649 Naming, Addressing and Registration X.650X.679 Abstract Syntax Notation One (ASN.1) X.680X.699 OSI MANAGEMENT Systems management framework and architecture X
6、.700X.709 Management communication service and protocol X.710X.719 Structure of management information X.720X.729 Management functions and ODMA functions X.730X.799 SECURITY X.800X.849 OSI APPLICATIONS Commitment, concurrency and recovery X.850X.859 Transaction processing X.860X.879 Remote operation
7、s X.880X.889 Generic applications of ASN.1 X.890X.899 OPEN DISTRIBUTED PROCESSING X.900X.999 INFORMATION AND NETWORK SECURITY X.1000X.1099 SECURE APPLICATIONS AND SERVICES X.1100X.1199 CYBERSPACE SECURITY X.1200X.1299 SECURE APPLICATIONS AND SERVICES X.1300X.1399 CYBERSECURITY INFORMATION EXCHANGE X
8、.1500X.1599 CLOUD COMPUTING SECURITY X.1600X.1699 For further details, please refer to the list of ITU-T Recommendations. Rec. ITU-T X.695 (08/2015) i INTERNATIONAL STANDARD ISO/IEC 8825-6 RECOMMENDATION ITU-T X.695 Information technology ASN.1 encoding rules: Registration and application of PER enc
9、oding instructions Summary Recommendation ITU-T X.695 | ISO/IEC 8825-6 specifies the rules for applying PER encoding instructions using either type prefixes or an encoding control section. Encoding instructions are a means of modifying the encodings of ASN.1 types for some specified encoding rule (i
10、n this case PER). They can be inserted in an ASN.1 specification in square brackets (much like a tag in the Basic Encoding Rules, BER) immediately before the type that they affect (type prefixes), or they can be collected together at the end of an ASN.1 module (an encoding control section). It also
11、specifies the procedures for developing, registering and publishing new PER encoding instructions from time to time. History Edition Recommendation Approval Study Group Unique ID* 1.0 ITU-T X.695 2007-05-29 17 11.1002/1000/9112 2.0 ITU-T X.695 2008-11-13 17 11.1002/1000/9613 3.0 ITU-T X.695 2015-08-
12、13 17 11.1002/1000/12488 _ * To access the Recommendation, type the URL http:/handle.itu.int/ in the address field of your web browser, followed by the Recommendations unique ID. For example, http:/handle.itu.int/11.1002/1000/11830-en. ii Rec. ITU-T X.695 (08/2015) FOREWORD The International Telecom
13、munication Union (ITU) is the United Nations specialized agency in the field of telecommunications, information and communication technologies (ICTs). The ITU Telecommunication Standardization Sector (ITU-T) is a permanent organ of ITU. ITU-T is responsible for studying technical, operating and tari
14、ff questions and issuing Recommendations on them with a view to standardizing telecommunications on a worldwide basis. The World Telecommunication Standardization Assembly (WTSA), which meets every four years, establishes the topics for study by the ITU-T study groups which, in turn, produce Recomme
15、ndations 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 which fall within ITU-Ts purview, the necessary standards are prepared on a collaborative basis with ISO and IEC. NOTE In this Recommend
16、ation, the expression “Administration“ is used for conciseness to indicate both a telecommunication administration and a recognized operating agency. Compliance with this Recommendation is voluntary. However, the Recommendation may contain certain mandatory provisions (to ensure, e.g., interoperabil
17、ity or applicability) and compliance with the Recommendation is achieved when all of these mandatory provisions are met. The words “shall“ or some other obligatory language such as “must“ and the negative equivalents are used to express requirements. The use of such words does not suggest that compl
18、iance with the Recommendation is required of any party. INTELLECTUAL PROPERTY RIGHTSITU draws attention to the possibility that the practice or implementation of this Recommendation may involve the use of a claimed Intellectual Property Right. ITU takes no position concerning the evidence, validity
19、or applicability of claimed Intellectual Property Rights, whether asserted by ITU members or others outside of the Recommendation development process. As of the date of approval of this Recommendation, ITU had not received notice of intellectual property, protected by patents, which may be required
20、to implement this Recommendation. However, implementers are cautioned that this may not represent the latest information and are therefore strongly urged to consult the TSB patent database at http:/www.itu.int/ITU-T/ipr/. ITU 2015 All rights reserved. No part of this publication may be reproduced, b
21、y any means whatsoever, without the prior written permission of ITU. Rec. ITU-T X.695 (08/2015) iii CONTENTS Page 1 Scope 1 2 Normative references 1 2.1 Identical Recommendations | International Standards 1 3 Definitions 1 4 Abbreviations . 2 5 Notation 2 6 Information to be provided to specify a PE
22、R encoding instruction 2 7 Status of a PER EI proposal during the approval process 3 8 Approval process 3 9 Publication by the Registration Authority 4 10 Restrictions on the use of PER Encoding Instructions . 4 11 Assigning a PER EI to an ASN.1 type using a type prefix . 4 12 Assigning a PER encodi
23、ng instruction using an encoding control section . 5 12.1 The encoding instruction assignment list 5 12.2 Identification of the targets for a PER encoding instruction using a target list . 5 12.2.1 General rules . 5 12.2.2 Target identification using an ASN.1 type reference and identifiers 7 12.2.3
24、Target identification using a built-in type name 8 12.2.4 Use of identifiers in context 8 13 Multiple assignment of PER encoding instructions 9 13.1 Order in which multiple assignments are considered 9 13.2 Effect of assigning a negating encoding instruction 9 13.3 Multiple assignment of PER encodin
25、g instructions 9 Annex A Example of the application of PER EIs using prefixed encoding instructions .11 Annex B Example of the application of PER EIs using targeted encoding instructions .14 Annex C Summary of the ASN.1 notation 16 iv Rec. ITU-T X.695 (08/2015) Introduction Rec. ITU-T X.680 | ISO/IE
26、C 8824-1 makes syntactic provision for the application of encoding instructions to modify the behaviour of a particular set of encoding rules, identified by an encoding reference (see Rec. ITU-T X.680 | ISO/IEC 8824-1). Rec. ITU-T X.691 | ISO/IEC 8825-2 specifies the BASIC-PER and CANONICAL-PER enco
27、ding rules, each with two variants: the ALIGNED variant and the UNALIGNED variant. The PER encoding instructions allow minor variations to be made in parts of the UNALIGNED variant of a BASIC-PER and CANONICAL-PER encoding. They have no effect on the ALIGNED variant of these encodings. NOTE The purp
28、ose of PER encoding instructions is to ease the task of producing an ASN.1 specification, which when encoded by the UNALIGNED variant of a PER encoding produces bit-patterns that exactly match those of a legacy protocol. It is unusual for the ALIGNED variant to be used for this purpose, and so for s
29、implicity all PER encoding instructions have no effect on the ALIGNED variant. This Recommendation | International Standard specifies the use of type prefixes and encoding control sections (see Rec. ITU-T X.680 | ISO/IEC 8824-1, 31.3 and clause 54) to associate one or more PER encoding instructions
30、with an ASN.1 type. Where an encoding instruction is associated with an ASN.1 type, specific clauses in Rec. ITU-T X.691 | ISO/IEC 8825-2 are amended according to the specification of the encoding instruction. These mechanisms are similar to those for the application of XER encoding instructions spe
31、cified in Rec. ITU-T X.693 | ISO/IEC 8825-4. This Recommendation | International Standard also specifies the procedures for the operation of a Registration Authority to receive, record and publish the specification of PER encoding instructions that are agreed from time to time. The Registration Auth
32、ority is the ITU Telecommunication Standardization Bureau, and the form of publication is an Implementers Guide for ASN.1. This Guide will be available freely on an ITU-T web-site. This Recommendation | International Standard also specifies the procedures to be used for the approval of new PER encod
33、ing instructions. Broadly, these procedures involve the prior publication in the Implementers Guide of a proposed new encoding instruction, with a later publication announcing that the new encoding instruction has been approved by a simple resolution of the relevant Study Group of ITU-T and the rele
34、vant Sub-Committee of ISO/IEC JTC 1. Clauses 6 to 9 specify the operation of the Registration Authority for PER encoding instructions. Clauses 10 to 13 specify the application of PER encoding instructions to an ASN.1 specification. Annex A is informative and contains an example of the application of
35、 PER encoding instructions using encoding prefixes. Annex B is informative and contains an example of the application of the same PER encoding instructions using an encoding control section. Annex C is informative and summarizes the productions defined in this Recommendation | International Standard
36、. ISO/IEC 8825-6:2015 (E) Rec. ITU-T X.695 (08/2015) 1 INTERNATIONAL STANDARD ITU-T RECOMMENDATION Information technology ASN.1 encoding rules: Registration and application of PER encoding instructions 1 Scope This Recommendation | International Standard: a) specifies the information needed and the
37、format to be used for specifying PER encoding instructions; b) specifies the mechanisms for approving new PER encoding instructions from time to time and the operation of the Registration Authority for PER encoding instructions; c) specifies the means of associating a PER encoding instruction with a
38、n ASN.1 type using both type prefixes and an encoding control section. 2 Normative references The following Recommendations and International Standards contain provisions which, through reference in this text, constitute provisions of this Recommendation | International Standard. At the time of publ
39、ication, the editions indicated were valid. All Recommendations and Standards are subject to revision, and parties to agreements based on this Recommendation | International Standard are encouraged to investigate the possibility of applying the most recent edition of the Recommendations and Standard
40、s listed below. Members of IEC and ISO maintain registers of currently valid International Standards. The Telecommunication Standardization Bureau of the ITU maintains a list of currently valid ITU-T Recommendations. 2.1 Identical Recommendations | International Standards Recommendation ITU-T X.680
41、(2015) | ISO/IEC 8824-1:2015, Information technology Abstract Syntax Notation One (ASN.1): Specification of basic notation. Recommendation ITU-T X.691 (2015) | ISO/IEC 8825-2:2015, Information technology ASN.1 encoding rules: Specification of Packed Encoding Rules (PER). 3 Definitions For the purpos
42、es of this Recommendation | International Standard, the definitions of Rec. ITU-T X.680 | ISO/IEC 8824-1 apply. The following additional definitions apply. 3.1 associated encoding instructions (for a type): A set of PER encoding instructions associated with a type. 3.2 final encoding instructions (f
43、or a type): The set of PER encoding instructions associated with a type as a result of the complete ASN.1 specification, and which are applied in producing encodings of that type. 3.3 identifying keyword: A word or hyphenated word that identifies a PER encoding instruction. 3.4 inherited encoding in
44、structions: PER encoding instructions that are associated with the type identified by a type reference. 3.5 Joint ITU-T | ISO/IEC JTC1 Collaborative Team for ASN.1: A group established in accordance with Rec. ITU-T A.23, Annex A and ISO/IEC JTC 1 Directives Edition 5 Version 2.0, subclause 2.6.4 and
45、 Annex K, clause 8 to progress work on Joint Text in relation to Abstract Syntax Notation One (ASN.1). 3.6 PER encoding instructions (PER EIs): Notation used to change the unaligned PER encoding of a type (or of a component of a type). NOTE PER encoding instructions are included in either a PER type
46、 prefix (see Rec. ITU-T X.680 | ISO/IEC 8824-1, 31.3) or a PER encoding control section (see Rec. ITU-T X.680 | ISO/IEC 8824-1, clause 54). 3.7 PER EI proposal: A proposal for a new PER encoding instruction that is progressing to either the REJECTED or the APPROVED state. ISO/IEC 8825-6:2015 (E) 2 R
47、ec. ITU-T X.695 (08/2015) 3.8 PER EI change proposal: A proposal for deletion of or change to an APPROVED PER encoding instruction that is progressing to either the REJECTED or the APPROVED state. NOTE PER EI change proposals are expected to be rare occurrences, and due consideration will be needed
48、to backwards compatibility considerations. 3.9 prefixed encoding instructions: PER encoding instructions that are assigned using a type prefix (see Annex A and Rec. ITU-T X.680 | ISO/IEC 8824-1, 31.3). NOTE Prefixed encoding instructions can delete, replace, or add to the associated encoding instruc
49、tions of a type. 3.10 relevant Study Group: The ITU-T Study Group that is responsible for the Joint ITU-T | ISO/IEC JTC1 Collaborative Team for ASN.1. 3.11 relevant Sub-Committee: The ISO/IEC JTC1 Sub-Committee that is responsible for the Joint ITU-T | ISO/IEC JTC1 Collaborative Team for ASN.1. 3.12 targeted encoding instructions: PER encoding instructions that are assigned using a target list in a PER encoding control section (see Annex B and Rec. ITU-T X.680 | ISO/IEC 8824-1, clause 54). NOT
