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Date: Tue, 09 Apr 2002 06:01:20 GMT Server: Apache/1.3.20 (Unix) Last-Modified: Wed, 09 Dec 1992 04:39:00 GMT ETag: "3dddf6-2f75-2b257864" Accept-Ranges: bytes Content-Length: 12149 Connection: close Content-Type: text/plain Network WorkingS.E. Hardcastle-KilleGroupUniversity College London INTERNET-DRAFT October 1992 Expires: AprilS. Hardcastle-Kille Request for Comments: 1485 ISODE Consortium July 1993 A String Representation of Distinguished Names (OSI-DS 23(v4))(v5)) Status of this Memo Thisdocument isRFC specifies anInternet Draft. Internet Drafts are working documents ofIAB standards track protocol for the InternetEngineering Task Force (IETF), its Areas,community, andits Working Groups. Note that other groups may also distribute working documents as Internet Drafts. Internet Drafts are draft documents validrequests discussion and suggestions fora maximum of six months. Internet Drafts may be updated, replaced, or obsoleted by other documents at any time. It is not appropriate to use Internet Drafts as reference material or to cite them other than as a "working draft" or "work in progress."improvements. Pleasecheck the I-D abstract listing contained in each Internet Draft directoryrefer tolearnthe current edition of the "IAB Official Protocol Standards" for the standardization state and status of thisor any other Internet Draft.protocol. Distribution of this memo is unlimited. Abstract The OSI Directory uses distinguished names as the primary keys to entries in the directory. Distinguished Names are encoded in ASN.1. When a distinguished name is communicated between to users not using a directory protocol (e.g., in a mail message), there is a need to have a user-oriented string representation of distinguished name. This specification defines a string format for representing names, which is designed to give a clean representation of commonly used names, whilst being able to represent any distinguished name.This draft document will be submitted to the RFC editor as a protocol standard. Distribution of this memo is unlimited.Please send comments to the author or to the discussion group <osi-ds@CS.UCL.AC.UK>.INTERNET--DRAFT DN Representation October 1992Table of Contents11. Why a notation isneeded 2 2needed...................................... 1 2. A notation for DistinguishedNameName............................. 2 2.1Goals . . . . . . . . . . .Goals......................................................... 2 2.2 Informaldefinition . . . . . . . .definition........................................... 2 2.3 Formaldefinition . . . . . . . .definition............................................. 32.3.1 An Alternative Approach . . . . .3. Examples...................................................... 63 Examples4. References.................................................... 645. SecurityConsiderations 7 5Considerations....................................... 6 6. Author'sAddressAddress.............................................. 7Hardcastle-Kille Expires: April 1993 Page 1 INTERNET--DRAFT DN Representation October 1992 11. Why a notation is needed Many OSI Applications make use of Distinguished Names (DN) as defined in the OSI Directory, commonly known as X.500 [CCI88]. This specification assumes familiarity with X.500, and the concept of Distinguished Name. It is important to have a common format to be able to unambiguously represent a distinguished name. This might be done to represent a directory name on a business card or in an email Hardcastle-Kille [Page 1] RFC 1485 Distinguished Names July 1993 message. There is a need for a format to support human to human communication, which must be string based (not ASN.1) and user oriented. This notation is targeted towards a general user oriented system, and in particular to represent the names of humans. Other syntaxes may be more appropriate for other uses of the directory. For example, the OSF Syntax may be more appropriate for some system oriented uses. (The OSF Syntax uses``/''"/" as a separator, and forms names in a manner intended to resemble UNIX filenames).22. A notation for Distinguished Name 2.1 Goals The following goals are laid out: o To provide an unambiguous representation of a distinguished name o To be an intuitive format for the majority of names o To be fully general, and able to represent any distinguished name o To be amenable to a number of different layouts to achieve an attractive representation. o To give a clear representation of the contents of the distinguished name 2.2 Informal definition This notation is designed to be convenient for common forms of name. Some examples are given. The author's directory distinguished nameHardcastle-Kille Expires: April 1993 Page 2 INTERNET--DRAFT DN Representation October 1992would be written: CN=Steve Hardcastle-Kille, OU=Computer Science, O=University College London, C=GB This may be folded, perhaps to display in multi-column format. For example: CN=Steve Hardcastle-Kille, OU=Computer Science, O=University College London, C=GB Hardcastle-Kille [Page 2] RFC 1485 Distinguished Names July 1993 Another name might be: CN=Christian Huitema, O=INRIA, C=FR Semicolon(``;'')(";") may be used as an alternate separator. CN=Christian Huitema; O=INRIA; C=FR In running text, this would be written as <CN=Christian Huitema; O=INRIA; C=FR>. Another example, shows how different attribute types are handled: CN=James Hacker, L=Basingstoke, O=Widget Inc, CN=GB Here is an example of a multi-valued Relative Distinguished Name, where the namespace is flat within an organisation, and department is used to disambiguate certain names: OU=Sales + CN=J. Smith, O=Widget Inc., C=US The final example shows quoting of a comma in an Organisation name: CN=L. Eagle, O="Sue, Grabbit and Runn", C=GB 2.3 Formal definition A formal definition can now be given. The structure is specified in a BNF grammar in Figure 1. This BNF uses the grammar defined inHardcastle-Kille Expires: April 1993 Page 3 INTERNET--DRAFT DN Representation October 1992RFC 822, with the terminals enclosed in <> [Cro82]. This definition is in an abstract character set, and so may be written in any character set supporting the explicitly defined special characters. The quoting mechanism is used for the following cases: o Strings containing``,'', ``+'', ``=''or ``"'' ,",", "+", "="or """, <CR>,``<'', ``>'', ``#'',"<", ">", "#", or``;''.";". o Strings with leading or trailing spaces o Strings containing consecutive spaces There is an escape mechanism from the normal user oriented form, so that this syntax may be used to print any valid distinguished name. This is ugly. It is expected to be used only in pathological cases. There are two parts to this mechanism: Hardcastle-Kille [Page 3] RFC 1485 Distinguished Names July 1993 1. Attributes types are represented in a (big-endian) dotted notation. (e.g., OID.2.6.53). 2. Attribute values are represented in hexadecimal(e.g.(e.g., #0A56CF). The keyword specification is optional in the BNF, but mandatory for this specification. This is so that the same BNF may be used for the related specification on User Friendly Naming[HK92].[HK93]. When this specification is followed, the attribute type keywords must always be present. A list of valid keywords for well known attribute types used in naming is given in Table 1. This is a list of keywords which must be supported. These are chosen because they appear in common forms of name, and can do so in a place which does not correspond to the default schema used.If other attributes are used for naming, this can always be extended locally.A register of valid keyworkds is maintained by the IANA. Only string type attributes are considered, but other attribute syntaxes could be supported locally. It is assumed that the interface will translate from the supplied string into PrintableString or T.61. The "+" notation is used to specify multi-component RDNs. In this case, the types for attributes in the RDN must be explicit. The name is presented/input in a little-endian order (most significant component last). When an address is written in a context where there is a need to delimit the entire address (e.g., in free text), it is recommended that the delimiters <> are used. The terminator > is a special in the notation to facilitate this delimitation. Hardcastle-KilleExpires: April[Page 4] RFC 1485 Distinguished Names July 1993Page 4 INTERNET--DRAFT DN Representation October 1992<name> ::= <name-component> ( <spaced-separator> ) | <name-component> <spaced-separator> <name> <spaced-separator> ::= <optional-space> <separator> <optional-space> <separator> ::= "," | ";" <optional-space> ::= ( <CR> ) *( " " ) <name-component> ::= <attribute> | <attribute> <optional-space> "+" <optional-space> <name-component> <attribute> ::= <string> | <key> <optional-space> "=" <optional-space> <string> <key> ::= 1*( <keychar> ) | "OID." <oid> <keychar> ::= letters, numbers, and space <oid> ::= <digitstring> | <digitstring> "." <oid> <digitstring> ::= 1*<digit> <digit> ::= digits 0-9 <string> ::= *( <stringchar> | <pair> ) | '"' *( <stringchar> | <special> | <pair> ) '"' | "#" <hex> <special> ::= "," | "=" | '"' | <CR> | "+" | "<" | ">" | "#" | ";" <pair> ::="\" ( <special> | "\" )" <stringchar> ::= any char except <special> or"\"" <hex> ::= 2*<hexchar> <hexchar> ::= 0-9, a-f, A-F Figure 1: BNF Grammar for Distinguished Name Hardcastle-KilleExpires: April[Page 5] RFC 1485 Distinguished Names July 1993Page 5 INTERNET--DRAFT DN Representation October 1992 _Key__Attribute_(X.520_keys)_Key Attribute (X.520 keys) ______________________________ CN CommonName L LocalityName ST StateOrProvinceName O OrganizationName OU OrganizationalUnitName C CountryName Table 1: Standardised KeywordsWhen an address is written in a context where there is a need to delimit the entire address (e.g., in free text), it is recommended that the delimiters <> are used. The terminator > is a special in the notation to facilitate this delimitation. 2.3.1 An Alternative Approach An alternative approach is described in this section. It is NOT recommended by these guidelines. Whilst this approach has merits, it is diametrically opposite to the recommended approach. A mixture of both approaches is not beneficial. This alternative is to use short names, which will be easily memorable by users (e.g., UCL for University College London, and CS for Computer Science). In general, the style of name component should be similar to that chosen for names in the domain system. The benefit of this approach is that it will lead to mnemonic names, which are easy to remember and to type. The directory will then be able to operate mainly on the read operation, with much less use of the more expensive search operation. It is argued that name conflicts may be dealt with by introducing more levels into the DIT. 33. Examples This section gives a few examples of distinguished names written using this notation:Hardcastle-Kille Expires: April 1993 Page 6 INTERNET--DRAFT DN Representation October 1992CN=Marshall T. Rose, O=Dover Beach Consulting, L=Santa Clara, ST=California, C=US CN=FTAM Service, CN=Bells, OU=Computer Science, O=University College London, C=GB CN=Steve Hardcastle-Kille, OU=Computer Science, O=University College London, C=GB CN=Steve Hardcastle-Kille, OU=Computer Science, O=University College London, C=GB 4. References [CCI88] The Directory --- overview of concepts, models and services, December 1988. CCITT X.500 Series Recommendations. [Cro82] D.H. Crocker. Standard of the format of ARPA internet text messages.Request for CommentsSTD 11, RFC 822, University of Delaware, August 1982.[HK92][HK93] S.E. Hardcastle-Kille. Using the OSI directory to achieve user friendly naming.Request for Comments in preparation,RFC 1484, Department of Computer Science, University College London,January 1992. 4July 1993. 5. Security Considerations Securityconsiderationsissues are not discussed in thisINTERNET--DRAFT . 5memo. Hardcastle-Kille [Page 6] RFC 1485 Distinguished Names July 1993 6. Author's Address Steve Hardcastle-KilleDepartment of Computer Science University CollegeISODE Consortium P.O. Box 505 LondonGower Street WC1E 6BT Hardcastle-Kille Expires: April 1993 Page 7 INTERNET--DRAFT DN Representation October 1992SW11 1DX EnglandPhone: +44-71-380-7294Phone:+44-71-223-4062 EMail:S.Kille@CS.UCL.AC.UKS.Kille@ISODE.COM DN: CN=Steve Hardcastle-Kille,OU=Computer Science, O=University College London,O=ISODE Consortium, C=GB UFN: S. Hardcastle-Kille,Computer Science, University College London,ISODE Consortium, GB Hardcastle-KilleExpires: April 1993 Page 8[Page 7] ----