1、 Reference numberISO/IEC 8825-2:2002(E)ISO/IEC 2002INTERNATIONAL STANDARD ISO/IEC8825-2Third edition2002-12-15Information technology ASN.1 encoding rules: Specification of Packed Encoding Rules (PER) Technologies de linformation Rgles de codage ASN.1: Spcification des rgles de codage compact (PER) A
2、dopted by INCITS (InterNational Committee for Information Technology Standards) as an American National Standard.Date of ANSI Approval: 12/28/2004Published by American National Standards Institute,25 West 43rd Street, New York, New York 10036Copyright 2004 by Information Technology Industry Council
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4、is publication may be reproduced in any form, including an electronic retrieval system, withoutthe prior written permission of ITI. All requests pertaining to this standard should be submitted to ITI, 1250 Eye Street NW,Washington, DC 20005.Printed in the United States of AmericaISO/IEC 8825-2:2002(
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8、/IEC 2002 All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized in any form or by any means, electronic or mechanical, including photocopying and microfilm, without permission in writing from either ISO at the address below or ISOs member body in
9、the country of the requester. ISO copyright office Case postale 56 CH-1211 Geneva 20 Tel. + 41 22 749 01 11 Fax + 41 22 749 09 47 E-mail copyrightiso.org Web www.iso.org Published by ISO in 2003 Published in Switzerland ii ISO/IEC 2002 All rights reservedISO/IEC 8825-2:2002(E) ISO/IEC 2002 All right
10、s reserved iiiCONTENTS Page Introduction . vi 1 Scope 1 2 Normative references . 1 2.1 Identical Recommendations | International Standards 1 2.2 Paired Recommendations | International Standards equivalent in technical content. 1 2.3 Additional references 1 3 Definitions 2 3.1 Specification of Basic
11、Notation. 2 3.2 Information Object Specification 2 3.3 Constraint Specification 2 3.4 Parameterization of ASN.1 Specification . 2 3.5 Basic Encoding Rules . 2 3.6 Additional definitions 2 4 Abbreviations . 5 5 Notation 5 6 Convention . 5 7 Encoding rules defined in this Recommendation | Internationa
12、l Standard. 5 8 Conformance 6 9 The approach to encoding used for PER 6 9.1 Use of the type notation 6 9.2 Use of tags to provide a canonical order . 7 9.3 PER-visible constraints . 7 9.4 Type and value model used for encoding 8 9.5 Structure of an encoding . 8 9.6 Types to be encoded 9 10 Encoding
13、procedures 10 10.1 Production of the complete encoding 10 10.2 Open type fields 10 10.3 Encoding as a non-negative-binary-integer. 10 10.4 Encoding as a 2s-complement-binary-integer 11 10.5 Encoding of a constrained whole number . 11 10.6 Encoding of a normally small non-negative whole number 12 10.
14、7 Encoding of a semi-constrained whole number 13 10.8 Encoding of an unconstrained whole number . 13 10.9 General rules for encoding a length determinant 13 11 Encoding the boolean type . 16 12 Encoding the integer type. 16 13 Encoding the enumerated type . 17 14 Encoding the real type 17 15 Encodin
15、g the bitstring type. 17 16 Encoding the octetstring type . 18 17 Encoding the null type 19 18 Encoding the sequence type . 19 19 Encoding the sequence-of type. 20 20 Encoding the set type . 20 21 Encoding the set-of type. 21 22 Encoding the choice type 21 ISO/IEC 8825-2:2002(E) iv ISO/IEC 2002 All
16、rights reserved23 Encoding the object identifier type. 22 24 Encoding the relative object identifier type 22 25 Encoding the embedded-pdv type 22 26 Encoding of a value of the external type 22 27 Encoding the restricted character string types 23 28 Encoding the unrestricted character string type 25
17、29 Object identifiers for transfer syntaxes. 25 Annex A Example of encodings . 27 A.1 Record that does not use subtype constraints. 27 A.1.1 ASN.1 description of the record structure . 27 A.1.2 ASN.1 description of a record value . 27 A.1.3 ALIGNED PER representation of this record value 27 A.1.4 UN
18、ALIGNED PER representation of this record value 28 A.2 Record that uses subtype constraints . 30 A.2.1 ASN.1 description of the record structure . 30 A.2.2 ASN.1 description of a record value . 30 A.2.3 ALIGNED PER representation of this record value 30 A.2.4 UNALIGNED PER representation of this rec
19、ord value 31 A.3 Record that uses extension markers. 32 A.3.1 ASN.1 description of the record structure . 32 A.3.2 ASN.1 description of a record value . 33 A.3.3 ALIGNED PER representation of this record value 33 A.3.4 UNALIGNED PER representation of this record value 34 A.4 Record that uses extensi
20、on addition groups. 36 A.4.1 ASN.1 description of the record structure . 36 A.4.2 ASN.1 description of a record value . 36 A.4.3 ALIGNED PER representation of this record value 36 A.4.4 UNALIGNED PER representation of this record value 37 Annex B Observations on combining PER-visible constraints. 38
21、 Annex C Support for the PER algorithms. 43 Annex D Support for the ASN.1 rules of extensibility . 44 Annex E Tutorial annex on concatenation of PER encodings 45 Annex F Assignment of object identifier values. 46 ISO/IEC 8825-2:2002(E) ISO/IEC 2002 All rights reserved vForeword ISO (the Internationa
22、l Organization for Standardization) and IEC (the International Electrotechnical Commission) form the specialized system for worldwide standardization. National bodies that are members of ISO or IEC participate in the development of International Standards through technical committees established by
23、the respective organization to deal with particular fields of technical activity. ISO and IEC technical committees collaborate in fields of mutual interest. Other international organizations, governmental and non-governmental, in liaison with ISO and IEC, also take part in the work. In the field of
24、information technology, ISO and IEC have established a joint technical committee, ISO/IEC JTC 1. International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2. The main task of the joint technical committee is to prepare International Standards. Draft Inter
25、national Standards adopted by the joint technical committee are circulated to national bodies for voting. Publication as an International Standard requires approval by at least 75 % of the national bodies casting a vote. Attention is drawn to the possibility that some of the elements of this documen
26、t may be the subject of patent rights. ISO and IEC shall not be held responsible for identifying any or all such patent rights. ISO/IEC 8825-2 was prepared by Joint Technical Committee ISO/IEC JTC 1, Information technology, Subcommittee SC 6, Telecommunications and information exchange between syste
27、ms, in collaboration with ITU-T. The identical text is published as ITU-T Rec. X.691. This third edition cancels and replaces the second edition (ISO/IEC 8825-2:1998), which has been technically revised. It also incorporates the Amendment ISO/IEC 8825-2:1998/Amd.1:2000 and the Technical Corrigenda I
28、SO/IEC 8825-2:1998/Cor.1:1999, ISO/IEC 8825-2:1998/Cor.2:2002 and ISO/IEC 8825-2:1998/Cor.3:2002. ISO/IEC 8825 consists of the following parts, under the general title Information technology ASN.1 encoding rules: Part 1: Specification of Basic Encoding Rules (BER), Canonical Encoding Rules (CER) and
29、 Distinguished Encoding Rules (DER) Part 2: Specification of Packed Encoding Rules (PER) Part 3: Specification of Encoding Control Notation (ECN) Part 4: XML Encoding Rules (XER) Part 5: Mapping W3C XML schema definitions into ASN.1 ISO/IEC 8825-2:2002(E) vi ISO/IEC 2002 All rights reservedIntroduct
30、ion The publications ITU-T Rec. X.680 | ISO/IEC 8824-1, ITU-T Rec. X.681 | ISO/IEC 8824-2, ITU-T Rec. X.682 | ISO/IEC 8824-3, ITU-T Rec. X.683 | ISO/IEC 8824-4 together describe Abstract Syntax Notation One (ASN.1), a notation for the definition of messages to be exchanged between peer applications.
31、 This Recommendation | International Standard defines encoding rules that may be applied to values of types defined using the notation specified in ITU-T Rec. X.680 | ISO/IEC 8824-1. Application of these encoding rules produces a transfer syntax for such values. It is implicit in the specification o
32、f these encoding rules that they are also to be used for decoding. There are more than one set of encoding rules that can be applied to values of ASN.1 types. This Recommendation | International Standard defines a set of Packed Encoding Rules (PER), so called because they achieve a much more compact
33、 representation than that achieved by the Basic Encoding Rules (BER) and its derivatives described in ITU-T Rec. X.690 | ISO/IEC 8825-1 which is referenced for some parts of the specification of these Packed Encoding Rules. ISO/IEC 8825-2:2003 (E) ITU-T Rec. X.691 (07/2002) 1 INTERNATIONAL STANDARD
34、ISO/IEC 8825-2 : 1995 (E) ITU-T Rec. X.691 (1995 E) ITU-T RECOMMENDATION Information technology ASN.1 encoding rules: Specification of Packed Encoding Rules (PER) 1 Scope This Recommendation | International Standard specifies a set of Packed Encoding Rules that may be used to derive a transfer synta
35、x for values of types defined in ITU-T Rec. X.680 | ISO/IEC 8824-1. These Packed Encoding Rules are also to be applied for decoding such a transfer syntax in order to identify the data values being transferred. The encoding rules specified in this Recommendation | International Standard: are used at
36、 the time of communication; are intended for use in circumstances where minimizing the size of the representation of values is the major concern in the choice of encoding rules; allow the extension of an abstract syntax by addition of extra values, preserving the encodings of the existing values, fo
37、r all forms of extension described in ITU-T Rec. X.680 | ISO/IEC 8824-1. 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 pu
38、blication, 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 Standa
39、rds 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 ITU-T Recommendation X.68
40、0 (2002) | ISO/IEC 8824-1:2002, Information technology Abstract Syntax Notation One (ASN.1): Specification of basic notation. ITU-T Recommendation X.681 (2002) | ISO/IEC 8824-2:2002, Information technology Abstract Syntax Notation One (ASN.1): Information object specification. ITU-T Recommendation X
41、.682 (2002) | ISO/IEC 8824-3:2002, Information technology Abstract Syntax Notation One (ASN.1): Constraint specification. ITU-T Recommendation X.683 (2002) | ISO/IEC 8824-4:2002, Information technology Abstract Syntax Notation One (ASN.1): Parameterization of ASN.1 specifications. ITU-T Recommendati
42、on X.690 (2002) | ISO/IEC 8825-1:2002, Information technology ASN.1 encoding rules: Specification of Basic Encoding Rules (BER), Canonical Encoding Rules (CER) and Distinguished Encoding Rules (DER). 2.2 Paired Recommendations | International Standards equivalent in technical content 2.3 Additional
43、references ISO/IEC 646:1991, Information technology ISO 7-bit coded character set for information interchange. ISO/IEC 2022:1994, Information technology Character code structure and extension techniques. ISO 2375:1985, Data processing Procedure for registration of escape sequences. ISO 6093:1985, In
44、formation processing Representation of numerical values in character strings for information interchange. ISO/IEC 8824-1:2002 (E)ISO/IEC 8825-1:2002 (E)ISO/IEC 8825-2:2002 (E)ISO/IEC 8825-2:2003 (E) 2 ITU-T Rec. X.691 (07/2002) ISO International Register of Coded Character Sets to be Used with Escap
45、e Sequences. ISO/IEC 10646-1:2000, Information technology Universal Multiple-Octet Coded Character Set (UCS) Part 1: Architecture and Basic Multilingual Plane. 3 Definitions For the purposes of this Recommendation | International Standard, the following definitions apply. 3.1 Specification of Basic
46、Notation For the purposes of this Recommendation | International Standard, all the definitions in ITU-T Rec. X.680 | ISO/IEC 8824-1 apply. 3.2 Information Object Specification For the purposes of this Recommendation | International Standard, all the definitions in ITU-T Rec. X.681 | ISO/IEC 8824-2 a
47、pply. 3.3 Constraint Specification This Recommendation | International Standard makes use of the following terms defined in ITU-T Rec. X.682 | ISO/IEC 8824-3: a) component relation constraint; b) table constraint. 3.4 Parameterization of ASN.1 Specification This Recommendation | International Standa
48、rd makes use of the following term defined in ITU-T Rec. X.683 | ISO/IEC 8824-4: variable constraint. 3.5 Basic Encoding Rules This Recommendation | International Standard makes use of the following terms defined in ITU-T Rec. X.690 | ISO/IEC 8825-1: a) dynamic conformance; b) static conformance; c)
49、 data value; d) encoding (of a data value); e) sender; f) receiver. 3.6 Additional definitions For the purposes of this Recommendation | International Standard, the following definitions apply. 3.6.1 2s-complement-binary-integer encoding: The encoding of a whole number into a bit-field (octet-aligned in the ALIGNED variant) of a specified length, or into the minimum number of octets that will accommodate that whole number encoded as a 2s-complement-intege
