1488
PROPOSED STANDARD
The X.500 String Representation of Standard Attribute Syntaxes (Obsoleted)
Authors: T. Howes, S. Kille, W. Yeong, C. Robbins
Date: July 1993
Area: app
Working Group: osids
Stream: IETF
Obsoleted by:
RFC 1778
Abstract
This document defines the requirements that must be satisfied by encoding rules used to render Directory attribute syntaxes into a form suitable for use in the LDAP, then goes on to define the encoding rules for the standard set of attribute syntaxes defined in [1,2] and [3]. [STANDARDS-TRACK]
RFC 1488
Obsoleted by: 1778 PROPOSED STANDARD
Network Working Group T. Howes
Request for Comments: 1488 University of Michigan
S. Kille
ISODE Consortium
W. Yeong
Performance Systems International
C. Robbins
NeXor Ltd.
July 1993
<span class="h1">The X.500 String Representation of Standard Attribute Syntaxes</span>
Status of this Memo
This RFC specifies an IAB standards track protocol for the Internet
community, and requests discussion and suggestions for improvements.
Please refer to the current edition of the "IAB Official Protocol
Standards" for the standardization state and status of this protocol.
Distribution of this memo is unlimited.
Abstract
The Lightweight Directory Access Protocol (LDAP) [<a href="#ref-9" title=""Lightweight Directory Access Protocol"">9</a>] requires that
the contents of AttributeValue fields in protocol elements be octet
strings. This document defines the requirements that must be
satisfied by encoding rules used to render Directory attribute
syntaxes into a form suitable for use in the LDAP, then goes on to
define the encoding rules for the standard set of attribute syntaxes
defined in [<a href="#ref-1">1</a>,<a href="#ref-2">2</a>] and [<a href="#ref-3" title=""The COSINE and Internet X.500 Schema"">3</a>].
<span class="h2"><a class="selflink" id="section-1" href="#section-1">1</a>. Attribute Syntax Encoding Requirements</span>
This section defines general requirements for lightweight directory
protocol attribute syntax encodings. All documents defining attribute
syntax encodings for use by the lightweight directory protocols are
expected to conform to these requirements.
The encoding rules defined for a given attribute syntax must produce
octet strings. To the greatest extent possible, encoded octet
strings should be usable in their native encoded form for display
purposes. In particular, encoding rules for attribute syntaxes
defining non-binary values should produce strings that can be
displayed with little or no translation by clients implementing the
lightweight directory protocols.
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<span class="h2"><a class="selflink" id="section-2" href="#section-2">2</a>. Standard Attribute Syntax Encodings</span>
For the purposes of defining the encoding rules for the standard
attribute syntaxes, the following auxiliary BNF definitions will be
used:
<a> ::= 'a' | 'b' | 'c' | 'd' | 'e' | 'f' | 'g' | 'h' | 'i' |
'j' | 'k' | 'l' | 'm' | 'n' | 'o' | 'p' | 'q' | 'r' |
's' | 't' | 'u' | 'v' | 'w' | 'x' | 'y' | 'z' | 'A' |
'B' | 'C' | 'D' | 'E' | 'F' | 'G' | 'H' | 'I' | 'J' |
'K' | 'L' | 'M' | 'N' | 'O' | 'P' | 'Q' | 'R' | 'S' |
'T' | 'U' | 'V' | 'W' | 'X' | 'Y' | 'Z'
<d> ::= '0' | '1' | '2' | '3' | '4' | '5' | '6' | '7' | '8' | '9'
<hex-digit> ::= <d> | 'a' | 'b' | 'c' | 'd' | 'e' | 'f' |
'A' | 'B' | 'C' | 'D' | 'E' | 'F'
<k> ::= <a> | <d> | '-'
<p> ::= <a> | <d> | ''' | '(' | ')' | '+' | ',' | '-' | '.' |
'/' | ':' | '?' | ' '
<CRLF> ::= The ASCII newline character with hexadecimal value 0x0A
<letterstring> ::= <a> | <a> <letterstring>
<numericstring> ::= <d> | <d> <numericstring>
<keystring> ::= <a> | <a> <anhstring>
<anhstring> ::= <k> | <k> <anhstring>
<printablestring> ::= <p> | <p> <printablestring>
<space> ::= ' ' | ' ' <space>
<span class="h3"><a class="selflink" id="section-2.1" href="#section-2.1">2.1</a>. Undefined</span>
Values of type Undefined are encoded as if they were values of type
Octet String.
<span class="h3"><a class="selflink" id="section-2.2" href="#section-2.2">2.2</a>. Case Ignore String</span>
A string of type caseIgnoreStringSyntax is encoded as the string
value itself.
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<span class="h3"><a class="selflink" id="section-2.3" href="#section-2.3">2.3</a>. Case Exact String</span>
The encoding of a string of type caseExactStringSyntax is the string
value itself.
<span class="h3"><a class="selflink" id="section-2.4" href="#section-2.4">2.4</a>. Printable String</span>
The encoding of a string of type printableStringSyntax is the string
value itself.
<span class="h3"><a class="selflink" id="section-2.5" href="#section-2.5">2.5</a>. Numeric String</span>
The encoding of a string of type numericStringSyntax is the string
value itself.
<span class="h3"><a class="selflink" id="section-2.6" href="#section-2.6">2.6</a>. Octet String</span>
The encoding of a string of type octetStringSyntax is the string
value itself.
<span class="h3"><a class="selflink" id="section-2.7" href="#section-2.7">2.7</a>. Case Ignore IA5 String</span>
The encoding of a string of type caseIgnoreIA5String is the string
value itself.
<span class="h3"><a class="selflink" id="section-2.8" href="#section-2.8">2.8</a>. IA5 String</span>
The encoding of a string of type iA5StringSyntax is the string value
itself.
<span class="h3"><a class="selflink" id="section-2.9" href="#section-2.9">2.9</a>. T61 String</span>
The encoding of a string of type t61StringSyntax is the string value
itself.
<span class="h3"><a class="selflink" id="section-2.10" href="#section-2.10">2.10</a>. Case Ignore List</span>
Values of type caseIgnoreListSyntax are encoded according to the
following BNF:
<caseignorelist> ::= <caseignorestring> |
<caseignorestring> '$' <caseignorelist>
<caseignorestring> ::= a string encoded according to the rules
for Case Ignore String as above.
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<span class="h3"><a class="selflink" id="section-2.11" href="#section-2.11">2.11</a>. Case Exact List</span>
Values of type caseExactListSyntax are encoded according to the
following BNF:
<caseexactlist> ::= <caseexactstring> |
<caseexactstring> '$' <caseexactlist>
<caseexactstring> ::= a string encoded according to the rules for
Case Exact String as above.
<span class="h3"><a class="selflink" id="section-2.12" href="#section-2.12">2.12</a>. Distinguished Name</span>
Values of type distinguishedNameSyntax are encoded to have the
representation defined in [<a href="#ref-5" title=""A String Representation of Distinguished Names"">5</a>].
<span class="h3"><a class="selflink" id="section-2.13" href="#section-2.13">2.13</a>. Boolean</span>
Values of type booleanSyntax are encoded according to the following
BNF:
<boolean> ::= "TRUE" | "FALSE"
Boolean values have an encoding of "TRUE" if they are logically true,
and have an encoding of "FALSE" otherwise.
<span class="h3"><a class="selflink" id="section-2.14" href="#section-2.14">2.14</a>. Integer</span>
Values of type integerSyntax are encoded as the decimal
representation of their values, with each decimal digit represented
by the its character equivalent. So the digit 1 is represented by the
character
<span class="h3"><a class="selflink" id="section-2.15" href="#section-2.15">2.15</a>. Object Identifier</span>
Values of type objectIdentifierSyntax are encoded according to the
following BNF:
<oid> ::= <descr> | <descr> '.' <numericoid> | <numericoid>
<descr> ::= <keystring>
<numericoid> ::= <numericstring> | <numericstring> '.' <numericoid>
In the above BNF, <descr> is the syntactic representation of an
object descriptor. When encoding values of type
objectIdentifierSyntax, the first encoding option should be used in
preference to the second, which should be used in preference to the
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third wherever possible. That is, in encoding object identifiers,
object descriptors (where assigned and known by the implementation)
should be used in preference to numeric oids to the greatest extent
possible. For example, in encoding the object identifier representing
an organizationName, the descriptor "organizationName" is preferable
to "ds.4.10", which is in turn preferable to the string "2.5.4.10".
<span class="h3"><a class="selflink" id="section-2.16" href="#section-2.16">2.16</a>. Telephone Number</span>
Values of type telephoneNumberSyntax are encoded as if they were
Printable String types.
<span class="h3"><a class="selflink" id="section-2.17" href="#section-2.17">2.17</a>. Telex Number</span>
Values of type telexNumberSyntax are encoded according to the
following BNF:
<telex-number> ::= <actual-number> '$' <country> '$' <answerback>
<actual-number> ::= <printablestring>
<country> ::= <printablestring>
<answerback> ::= <printablestring>
In the above, <actual-number> is the syntactic representation of the
number portion of the TELEX number being encoded, <country> is the
TELEX country code, and <answerback> is the answerback code of a
TELEX terminal.
<span class="h3"><a class="selflink" id="section-2.18" href="#section-2.18">2.18</a>. Teletex Terminal Identifier</span>
Values of type teletexTerminalIdentifier are encoded according to the
following BNF:
<teletex-id> ::= <printablestring> 0*( '$' <printablestring>)
In the above, the first <printablestring> is the encoding of the
first portion of the teletex terminal identifier to be encoded, and
the subsequent 0 or more <printablestrings> are subsequent portions
of the teletex terminal identifier.
<span class="h3"><a class="selflink" id="section-2.19" href="#section-2.19">2.19</a>. Facsimile Telephone Number</span>
Values of type FacsimileTelephoneNumber are encoded according to the
following BNF:
<fax-number> ::= <printablestring> [ '$' <faxparameters> ]
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<faxparameters> ::= <faxparm> | <faxparm> '$' <faxparameters>
<faxparm> ::= 'twoDimensional' | 'fineResolution' | 'unlimitedLength' |
'b4Length' | 'a3Width' | 'b4Width' | 'uncompressed'
In the above, the first <printablestring> is the actual fax number,
and the <faxparm> tokens represent fax parameters.
<span class="h3"><a class="selflink" id="section-2.20" href="#section-2.20">2.20</a>. Presentation Address</span>
Values of type PresentationAddress are encoded to have the
representation described in [<a href="#ref-6" title=""A String Representation for Presentation Addresses"">6</a>].
<span class="h3"><a class="selflink" id="section-2.21" href="#section-2.21">2.21</a>. UTC Time</span>
Values of type uTCTimeSyntax are encoded as if they were Printable
Strings with the strings containing a UTCTime value.
<span class="h3"><a class="selflink" id="section-2.22" href="#section-2.22">2.22</a>. Guide (search guide)</span>
Values of type Guide, such as values of the searchGuide attribute,
are encoded according to the following BNF:
<guide-value> ::= [ <object-class> '#' ] <criteria>
<object-class> ::= an encoded value of type objectIdentifierSyntax
<criteria> ::= <criteria-item> | <criteria-set> | '!' <criteria>
<criteria-set> ::= [ '(' ] <criteria> '&' <criteria-set> [ ')' ] |
[ '(' ] <criteria> '|' <criteria-set> [ ')' ]
<criteria-item> ::= [ '(' ] <attributetype> '$' <match-type> [ ')' ]
<match-type> ::= "EQ" | "SUBSTR" | "GE" | "LE" | "APPROX"
<span class="h3"><a class="selflink" id="section-2.23" href="#section-2.23">2.23</a>. Postal Address</span>
Values of type PostalAddress are encoded according to the following BNF:
<postal-address> ::= <t61string> | <t61string> '$' <postal-address>
In the above, each <t61string> component of a postal address value is
encoded as a value of type t61StringSyntax.
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<span class="h3"><a class="selflink" id="section-2.24" href="#section-2.24">2.24</a>. User Password</span>
Values of type userPasswordSyntax are encoded as if they were of type
octetStringSyntax.
<span class="h3"><a class="selflink" id="section-2.25" href="#section-2.25">2.25</a>. User Certificate</span>
Values of type userCertificate are encoded according to the following
BNF:
<certificate> ::= <signature> '#' <issuer> '#' <validity> '#' <subject>
'#' <public-key-info>
<signature> ::= <algorithm-id>
<issuer> ::= an encoded Distinguished Name
<validity> ::= <not-before-time> '#' <not-after-time>
<not-before-time> ::= <utc-time>
<not-after-time> ::= <utc-time>
<algorithm-parameters> ::= <null> | <integervalue> |
'{ASN}' <hex-string>
<subject> ::= an encoded Distinguished Name
<public-key-info> ::= <algorithm-id> '#' <encrypted-value>
<encrypted-value> ::= <hex-string> | <hex-string> '-' <d>
<algorithm-id> ::= <oid> '#' <algorithm-parameters>
<utc-time> ::= an encoded UTCTime value
<hex-string> ::= <hex-digit> | <hex-digit> <hex-string>
<span class="h3"><a class="selflink" id="section-2.26" href="#section-2.26">2.26</a>. CA Certificate</span>
Values of type cACertificate are encoded as if the values were of
type userCertificate.
<span class="h3"><a class="selflink" id="section-2.27" href="#section-2.27">2.27</a>. Authority Revocation List</span>
Values of type authorityRevocationList are encoded according to the
following BNF:
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<certificate-list> ::= <signature> '#' <issuer> '#'
<utc-time> [ '#' <revoked-certificates> ]
<revoked-certificates> ::= <algorithm> '#' <encrypted-value>
[ '#' 0*(<revoked-certificate>) '#']
<revoked-certificates> ::= <subject> '#' <algorithm> '#'
<serial> '#' <utc-time>
The syntactic components <algorithm>, <issuer>, <encrypted-value>,
<utc-time>, <subject> and <serial> have the same definitions as in
the BNF for the userCertificate attribute syntax.
<span class="h3"><a class="selflink" id="section-2.28" href="#section-2.28">2.28</a>. Certificate Revocation List</span>
Values of type certificateRevocationList are encoded as if the values
were of type authorityRevocationList.
<span class="h3"><a class="selflink" id="section-2.29" href="#section-2.29">2.29</a>. Cross Certificate Pair</span>
Values of type crossCertificatePair are encoded according to the
following BNF:
<certificate-pair> ::= <certificate> '|' <certificate>
The syntactic component <certificate> has the same definition as in
the BNF for the userCertificate attribute syntax.
<span class="h3"><a class="selflink" id="section-2.30" href="#section-2.30">2.30</a>. Delivery Method</span>
Values of type deliveryMethod are encoded according to the following
BNF:
<delivery-value> ::= <pdm> | <pdm> '$' <delivery-value>
<pdm> ::= 'any' | 'mhs' | 'physical' | 'telex' | 'teletex' |
'g3fax' | 'g4fax' | 'ia5' | 'videotex' | 'telephone'
<span class="h3"><a class="selflink" id="section-2.31" href="#section-2.31">2.31</a>. Other Mailbox</span>
Values of the type otherMailboxSyntax are encoded according to the
following BNF:
<otherMailbox> ::= <mailbox-type> '$' <mailbox>
<mailbox-type> ::= an encoded Printable String
<mailbox> ::= an encoded IA5 String
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In the above, <mailbox-type> represents the type of mail system in
which the mailbox resides, for example "Internet" or "MCIMail"; and
<mailbox> is the actual mailbox in the mail system defined by
<mailbox-type>.
<span class="h3"><a class="selflink" id="section-2.32" href="#section-2.32">2.32</a>. Mail Preference</span>
Values of type mailPreferenceOption are encoded according to the
following BNF:
<mail-preference> ::= "NO-LISTS" | "ANY-LIST" | "PROFESSIONAL-LISTS"
<span class="h3"><a class="selflink" id="section-2.33" href="#section-2.33">2.33</a>. MHS OR Address</span>
Values of type MHS OR Address are encoded as strings, according to
the format defined in [<a href="#ref-10" title=""Mapping between X.400(1988)/ISO 10021 and RFC 822"">10</a>].
<span class="h3"><a class="selflink" id="section-2.34" href="#section-2.34">2.34</a>. Photo</span>
Values of type Photo are encoded as if they were octet strings
containing JPEG images in the JPEG File Interchange Format (JFIF), as
described in [<a href="#ref-8" title="September 1">8</a>].
<span class="h3"><a class="selflink" id="section-2.35" href="#section-2.35">2.35</a>. Fax</span>
Values of type Fax are encoded as if they were octet strings
containing Group 3 Fax images as defined in [<a href="#ref-7">7</a>].
<span class="h2"><a class="selflink" id="section-3" href="#section-3">3</a>. Acknowledgements</span>
Many of the attribute syntax encodings defined in this document are
adapted from those used in the QUIPU X.500 implementation. The
contribu- tions of the authors of the QUIPU implementation in the
specification of the QUIPU syntaxes [<a href="#ref-4">4</a>] are gratefully acknowledged.
<span class="h2"><a class="selflink" id="section-4" href="#section-4">4</a>. Bibliography</span>
[<a id="ref-1">1</a>] The Directory: Selected Attribute Syntaxes. CCITT,
Recommendation X.520.
[<a id="ref-2">2</a>] Information Processing Systems -- Open Systems Interconnection --
The Directory: Selected Attribute Syntaxes.
[<a id="ref-3">3</a>] Barker, P., and S. Kille, "The COSINE and Internet X.500 Schema",
<a href="./rfc1274">RFC 1274</a>, University College London, November 1991.
[<a id="ref-4">4</a>] The ISO Development Environment: User's Manual -- Volume 5:
QUIPU. Colin Robbins, Stephen E. Kille.
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[<a id="ref-5">5</a>] Kille, S., "A String Representation of Distinguished Names", <a href="./rfc1485">RFC</a>
<a href="./rfc1485">1485</a>, July 1993.
[<a id="ref-6">6</a>] Kille, S., "A String Representation for Presentation Addresses",
<a href="./rfc1278">RFC 1278</a>, University College London, November 1991.
[<a id="ref-7">7</a>] Terminal Equipment and Protocols for Telematic Services -
Standardization of Group 3 facsimile apparatus for document
transmission. CCITT, Recommendation T.4.
[<a id="ref-8">8</a>] JPEG File Interchange Format (Version 1.02). Eric Hamilton, C-
Cube Microsystems, Milpitas, CA, September 1, 1992.
[<a id="ref-9">9</a>] Yeong, W., Howes, T., and S. Kille, "Lightweight Directory Access
Protocol", <a href="./rfc1487">RFC 1487</a>, Performance Systems International,
University of Michigan, ISODE Consortium, July 1993.
[<a id="ref-10">10</a>] Kille, S., "Mapping between X.400(1988)/ISO 10021 and <a href="./rfc822">RFC 822</a>",
<a href="./rfc1327">RFC 1327</a>, University College London, May 1992.
<span class="h2"><a class="selflink" id="section-5" href="#section-5">5</a>. Security Considerations</span>
Security issues are not discussed in this memo.
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<span class="h2"><a class="selflink" id="section-6" href="#section-6">6</a>. Authors' Addresses</span>
Tim Howes
University of Michigan
ITD Research Systems
535 W William St.
Ann Arbor, MI 48103-4943
USA
Phone: +1 313 747-4454
EMail: [email protected]
Steve Kille
ISODE Consortium
PO Box 505
London
SW11 1DX
UK
Phone: +44-71-223-4062
EMail: [email protected]
Wengyik Yeong
PSI, Inc.
510 Huntmar Park Drive
Herndon, VA 22070
USA
Phone: +1 703-450-8001
EMail: [email protected]
Colin Robbins
NeXor Ltd
University Park
Nottingham
NG7 2RD
UK
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