1、BRITISH STANDARD BS ISO 10126-2:1991 Implementation of ISO 10126-2:1991 Banking Proceduresfor message encipherment (wholesale) Part 2: DEA algorithm UDC 336.719.2:355.405.2:681.3.04BSISO10126-2:1991 This British Standard, having been prepared under the directionof the Information Systems Technology
2、Standards Policy Committee, was publishedunder the authority ofthe Standards Board and comesinto effect on 31 January 1992 BSI 09-1999 The following BSI references relate to the work on this standard: Committee reference IST/12 Draft for comment 89/63556 DC ISBN 0 580 20453 7 Committees responsible
3、for this British Standard The preparation of this British Standard was entrusted by the Information Systems Technology Standards Policy Committee (IST/-) to Technical Committee IST/12, upon which the following bodies were represented: American Banks and Securities Association of London Association f
4、or Payment Clearing Services Building Societies Association British Telecommunications plc IBM (UK) Ltd. The London Stock Exchange The following bodies were also represented in the drafting of the standard, through subcommittees and panels: British Bankers Association Institutional Fund Managers Ass
5、ociation Securities and Investments Board Stock Exchange Management Association The EDI Association The London Stock Exchange Amendments issued since publication Amd. No. Date CommentsBSISO10126-2:1991 BSI 09-1999 i Contents Page Committees responsible Inside front cover National foreword ii Forewor
6、d iii Text of ISO 10126-2 1BSISO10126-2:1991 ii BSI 09-1999 National foreword This British Standard reproduces verbatim ISO10126-2:1991 and implements it as the UK national standard. This British Standard is published under the direction of the Information Systems Technology Standards Policy Committ
7、ee whose Technical Committee IST/12 has the responsibility to: aid enquirers to understand the text; present to the responsible international committee any enquiries on interpretation, or proposals for change, and keep UK interests informed; monitor related international and European developments an
8、d promulgate them in the UK. NOTEInternational and European Standards, as well as overseas standards, are available from BSI Sales Department, BSI, Linford Wood, Milton Keynes, MK14 6LE. A British Standard does not purport to include all the necessary provisions of a contract. Users of British Stand
9、ards are responsible for their correct application. Compliance with a British Standard does not of itself confer immunity from legal obligations. Summary of pages This document comprises a front cover, an inside front cover, pages i and ii, the ISO title page, pages ii to iv, pages 1 to 3 and a back
10、 cover. This standard has been updated (see copyright date) and may have had amendments incorporated. This will be indicated in the amendment table on the inside front cover.ISO10126-2:1991(E) ii BSI 09-1999 Contents Page Foreword iii 1 Scope 1 2 Normative references 1 3 Modes of operation 1 4 Initi
11、alization Vectors (IVs) 1 5 Initial Text Sequence (ITS) 1 6 Padding field (CBC mode only) 1 7 Independent encipherment and decipherment of encipherment elements 3 Figure 1 Message padding 1 Figure 2 Padding field format 2 Table 1 Padding with bits (CBC mode only) 2 Table 2 Padding with octets (CBC m
12、ode only) 2 Descriptors: Banking, messages, protection of information, coded representation, algorithms.ISO10126-2:1991(E) BSI 09-1999 iii Foreword ISO (the International Organization for Standardization) is a worldwide federation of national standards bodies (ISO member bodies). The work of prepari
13、ng International Standards is normally carried out through ISO technical committees. Each member body interested in a subject for which a technical committee has been established has the right to be represented on that committee. International organizations, governmental and non-governmental, in lia
14、ison with ISO, also take part in the work. ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization. Draft International Standards adopted by the technical committees are circulated to the member bodies for voting. Publicati
15、on as an International Standard requires approval by at least 75% of the member bodies casting a vote. International Standard ISO 10126-2 was prepared by Technical Committee ISO/TC68, Banking and related financial services. ISO10126 consists of the following parts, under the general title Banking Pr
16、ocedures for message encipherment (wholesale): Part 1: General principles; Part 2: DEA algorithm. ISO10126 originates from work done in ANSI, and is a development of (while remaining compatible with) ANSI X9.23 (1988), Financial Institution: Encryption of Wholesale Financial Messages.iv blankISO1012
17、6-2:1991(E) BSI 09-1999 1 1 Scope ISO 10126-1 specifies a method for the encipherment and decipherment of entire (or part of) wholesale financial messages by the use of application level encipherment, for the purpose of providing confidentiality. DEA may be used as a suitable algorithm to implement
18、ISO10126-1. It is specified in ANSI X3.92. Keys shall be managed in accordance with ISO8732. 2 Normative references The following standards contain provisions which, through reference in this text, constitute provisions of this part of ISO10126. At the time of publication, the editions indicated wer
19、e valid. All standards are subject to revision, and parties to agreements based on this part of ISO10126 are encouraged to investigate the possibility of applying the most recent editions of the standards indicated below. Members of IEC and ISO maintain registers of currently valid International Sta
20、ndards. ISO 8372:1987, Information processing Modes of operation for a 64-bit block cipher algorithm. ISO 8732:1988, Banking Key management (wholesale). ISO 10126-1:1991, Banking Procedures for message encipherment (wholesale) Part 1: General principles 1) . ANSI X3.92:1981, American National Standa
21、rd for information Systems Data Encryption Algorithm. 3 Modes of operation The modes of operation that shall be used are Cipher Block Chaining (CBC), One Bit Cipher Feedback (CFB-1) or Eight Bit Cipher Feedback (CFB-8) as defined in ISO8732. 4 Initialization Vectors (IVs) An IV is used as a starting
22、 point for the encipherment and decipherment of a data sequence to increase security by introducing additional cryptographic variance (i.e. a repeated plaintext sequence will not result in a repeated ciphertext sequence) and to synchronize cryptographic equipment. 4.1 Cipher Block Chaining (CBC) A n
23、ew random, pseudo-random or non-repeating 64-bit IV shall be used for each cryptoperiod. The same IV may be used within the cryptoperiod of the associated key. 4.2 Cipher Feedback (CFB) A new random, pseudo-random, or non-repeating48- or 64-bit IV shall be used for each message. 5 Initial Text Seque
24、nce (ITS) In the case of CBC, if the IV is not changed for each message, then a new random, pseudo-random, or non-repeating 64-bit Initial Text Sequence (ITS) shall immediately precede the message data to be protected. If a new random, pseudo-random, or non-repeating IV is used for each message, the
25、n no ITS is required. 6 Padding field (CBC mode only) Padding shall be present in every CBC message. Plaintext shall be padded to a multiple of 64bits before encipherment using the CBC mode. Padding shall be performed using either bits or octets by appending a padding field to the end of the plainte
26、xt (as shown cross-hatched inFigure 1). After decipherment, the padding field shall be discarded. When padding with bits, the padding field shall consist of 8 to 71bits divided into two subfields (seeFigure 2). The first subfield (pad fill) shall consist of 0 to 63bits with arbitrary contents. The s
27、econd sub-field (pad count) shall consist of 8bits containing the number of bits in the padding field. In the range 8 to 71. The left-most bit of the pad count shall indicate that the pad count is given in bits (value of 1). The remaining bits of the pad count shall contain an unsigned binary number
28、. That number shall be the total number of bits in the padding field. SeeTable 1 for further information on padding with bits (CBC mode only). 1) To be published. Figure 1 Message paddingISO10126-2:1991(E) 2 BSI 09-1999 When padding with octets, the padding field shall consist of 1 to 8octets divide
29、d into two subfields (seeFigure 2). The first subfield (pad fill) shall consist of0to7octets with arbitrary contents. The second subfield (pad count) shall consist of one octet containing the number of octets in the padding field in the range of1to8. The left-most bit of the pad count shall indicate
30、 that the pad count is given in octets (value of0). The remaining bits of the pad count shall contain an unsigned binary number. That number shall be the total number of padding octets in the padding field. SeeTable 2 for further information on padding with octets (CBC mode only). Table 1 Padding wi
31、th bits (CBC mode only) Table 2 Padding with octets (CBC mode only) NOTEWhen n = 1, pad count in bits; when n = 0, pad count in octets. Figure 2 Padding field format Number of bits in last plaintext block Number of bits in pad fill Number of bits in padding field Pad count (8 bits) 64 56 64 11000000
32、 63 57 65 11000001 62 58 66 11000010 . . . . . . . . . . . . 58 62 70 11000110 57 63 71 11000111 56 0 8 10001000 55 1 9 10001001 54 2 10 10001010 . . . . . . . . . . . . 2 54 62 10111110 1 55 63 10111111 Number of octets in last plaintext block Number of octets in pad fill Number of octets in paddin
33、g field Pad count (8 bits) 8 7 8 00001000 7 0 1 00000001 6 1 2 00000010 5 2 3 00000011 4 3 4 00000100 3 4 5 00000101 2 5 6 00000110 1 6 7 00000111ISO10126-2:1991(E) BSI 09-1999 3 7 Independent encipherment and decipherment of encipherment elements See ISO10126-1:1991, 5.3, method 1. The IV used to e
34、ncipher the nth encipherment element shall be formed by modulo-2 adding the IV and the right justified unsigned binary value of n: IVn = IV + n. For the first encipherment, element n shall have the value1. In the case of CBC, if the IV is not changed for each message, then a new random, pseudo-rando
35、m, or non-repeating ITS shall appear at the beginning of each encipherment element. In the case of CBC, each encipherment element shall be padded before encipherment in accordance with clause6.BS ISO 10126-2:1991 BSI 389 Chiswick High Road London W4 4AL BSIBritishStandardsInstitution BSI is the inde
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