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draft-ietf-osids-dist-names
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Network Working S.E. Kille
Group ISODE Consortium
INTERNET-DRAFT November 1994
Obsoletes: RFC 1485 Expires: May 1995
File:
draft-ietf-osids-dist-names-00.txt,ps
A String Representation of Distinguished Names
Status of this Memo
This document is an Internet Draft. Internet Drafts are working
documents of the Internet Engineering Task Force (IETF), its Areas,
and its Working Groups. Note that other groups may also distribute
working documents as Internet Drafts.
Internet Drafts are draft documents valid for a maximum of six months.
Internet Drafts may be updated, replaced, or obsoleted by other
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Please check the I-D abstract listing contained in each Internet Draft
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Draft.
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 November 1994
Contents
1 Why a notation is needed 2
2 A notation for Distinguished Name 2
2.1 Goals . . . . . . . . . . . 2
2.2 Informal definition . . . . . . . . 2
2.3 Formal definition . . . . . . . . 4
3 Examples 6
4 Acknowledgements 7
5 Security Considerations 8
6 Author's Address 8
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INTERNET--DRAFT DN Representation November 1994
1 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 [1]. 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 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).
2 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 name
would be written:
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INTERNET--DRAFT DN Representation November 1994
CN=Steve Kille,
O=ISODE Consortium, C=GB
This may be folded, perhaps to display in multi-column format. For
example:
CN=Steve Kille,
O=ISODE Consortium,
C=GB
Another name might be:
CN=Christian Huitema, O=INRIA, C=FR
Semicolon (``;'') may be used as an alternate separator. The
separators may be mixed, but this usage is discouraged.
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,
C=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 examples show both methods quoting of a comma in an
Organisation name:
CN=L. Eagle, O="Sue, Grabbit and Runn", C=GB
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INTERNET--DRAFT DN Representation November 1994
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 in
RFC 822, with the terminals enclosed in <> [2]. 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 ``"'' , <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:
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. #0A56CF).
Each pair of hex digits defines an octet, which is the ASN.1 Basic
Encoding Rules value of the Attribute Value.
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 [5]. 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. Keywords may contain spaces, but shall not have
leading or trailing spaces. 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
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<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> | "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 character except <special> or "\" or '"'
<hex> ::= 2*<hexchar>
<hexchar> ::= 0-9, a-f, A-F
Figure 1: BNF Grammar for Distinguished Name
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_Key_____Attribute_(X.520_keys)_
CN CommonName
L LocalityName
ST StateOrProvinceName
O OrganizationName
OU OrganizationalUnitName
C CountryName
STREET StreetAddress
Table 1: Standardised Keywords
default schema used. A register of valid keywords is maintained by
the IANA.
Only string type attributes are considered, but other attribute
syntaxes could be supported locally (e.g., by use of the syntexes
defined in [3].) It is assumed that the interface will translate from
the supplied string into an appropriate Directory String encoding.
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.
3 Examples
This section gives a few examples of distinguished names written using
this notation:
CN=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
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INTERNET--DRAFT DN Representation November 1994
CN=Markus Kuhn, O=University of Erlangen, C=DE
CN=Steve Kille,
O=ISODE Consortium,
C=GB
CN=Steve Kille ,
O = ISODE Consortium,
C=GB
CN=Steve Kille, O=ISODE Consortium, C=GB
4 Acknowledgements
This work was based on research work done at University College London
[4], and evolved by the IETF OSI-DS WG.
Input for this version of the document was received from: Allan
Cargille (University of Wisconsin); John Dale (COS); Philip Gladstone
(Onsett); John Hawthorne (US Air Force); Roland Hedberg (University of
Umea); Kipp Hickman (Mosaic Communications Corp.) Markus Kuhn
(University of Erlangen); Elisabeth Roudier (E3X); Mark Wahl (ISODE
Consortium).
References
[1] The Directory --- overview of concepts, models and services,
1993. CCITT X.500 Series Recommendations.
[2] D.H. Crocker. Standard of the format of ARPA internet text
messages. Request for Comments 822, University of Delaware,
August 1982.
[3] T. Howes, S. Kille, W. Yeong, and C. Robbins. The X.500 string
representation of standard attribute syntaxes. Request for
Comments 1488, July 1993.
[4] S.E. Kille. Using the OSI directory to achieve user friendly
naming. Research Note RN/20/29, Department of Computer Science,
University College London, February 1990.
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INTERNET--DRAFT DN Representation November 1994
[5] S.E. Kille. Using the OSI directory to achieve user friendly
naming. Request for Comments in preparation, ISODE Consortium,
November 1994.
5 Security Considerations
Security considerations are not discussed in this INTERNET--DRAFT.
6 Author's Address
Steve Kille
ISODE Consortium
The Dome
The Square
Richmond, Surrey
TW9 1DT
England
Phone:+44-181-332-9091
EMail: S.Kille@ISODE.COM
DN: CN=Steve Kille,
O=ISODE Consortium, C=GB
UFN: S. Kille,
ISODE Consortium, GB
Kille Expires: May 1995 Page 8
