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844 lines
31 KiB
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844 lines
31 KiB
Plaintext
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Network Working Group K. Zeilenga, Ed.
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Request for Comments: 4514 OpenLDAP Foundation
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Obsoletes: 2253 June 2006
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Category: Standards Track
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Lightweight Directory Access Protocol (LDAP):
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String Representation of Distinguished Names
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Status of This Memo
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This document specifies an Internet standards track protocol for the
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Internet community, and requests discussion and suggestions for
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improvements. Please refer to the current edition of the "Internet
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Official Protocol Standards" (STD 1) for the standardization state
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and status of this protocol. Distribution of this memo is unlimited.
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Copyright Notice
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Copyright (C) The Internet Society (2006).
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Abstract
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The X.500 Directory uses distinguished names (DNs) as primary keys to
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entries in the directory. This document defines the string
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representation used in the Lightweight Directory Access Protocol
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(LDAP) to transfer distinguished names. The string representation is
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designed to give a clean representation of commonly used
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distinguished names, while being able to represent any distinguished
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name.
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1. Background and Intended Usage
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In X.500-based directory systems [X.500], including those accessed
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using the Lightweight Directory Access Protocol (LDAP) [RFC4510],
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distinguished names (DNs) are used to unambiguously refer to
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directory entries [X.501][RFC4512].
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The structure of a DN [X.501] is described in terms of ASN.1 [X.680].
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In the X.500 Directory Access Protocol [X.511] (and other ITU-defined
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directory protocols), DNs are encoded using the Basic Encoding Rules
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(BER) [X.690]. In LDAP, DNs are represented in the string form
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described in this document.
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It is important to have a common format to be able to unambiguously
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represent a distinguished name. The primary goal of this
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specification is ease of encoding and decoding. A secondary goal is
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to have names that are human readable. It is not expected that LDAP
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Zeilenga Standards Track [Page 1]
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RFC 4514 LDAP: Distinguished Names June 2006
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implementations with a human user interface would display these
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strings directly to the user, but that they would most likely be
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performing translations (such as expressing attribute type names in
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the local national language).
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This document defines the string representation of Distinguished
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Names used in LDAP [RFC4511][RFC4517]. Section 2 details the
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RECOMMENDED algorithm for converting a DN from its ASN.1 structured
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representation to a string. Section 3 details how to convert a DN
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from a string to an ASN.1 structured representation.
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While other documents may define other algorithms for converting a DN
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from its ASN.1 structured representation to a string, all algorithms
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MUST produce strings that adhere to the requirements of Section 3.
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This document does not define a canonical string representation for
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DNs. Comparison of DNs for equality is to be performed in accordance
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with the distinguishedNameMatch matching rule [RFC4517].
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This document is a integral part of the LDAP technical specification
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[RFC4510], which obsoletes the previously defined LDAP technical
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specification, RFC 3377, in its entirety. This document obsoletes
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RFC 2253. Changes since RFC 2253 are summarized in Appendix B.
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This specification assumes familiarity with X.500 [X.500] and the
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concept of Distinguished Name [X.501][RFC4512].
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1.1. Conventions
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The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
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"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
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document are to be interpreted as described in BCP 14 [RFC2119].
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Character names in this document use the notation for code points and
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names from the Unicode Standard [Unicode]. For example, the letter
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"a" may be represented as either <U+0061> or <LATIN SMALL LETTER A>.
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Note: a glossary of terms used in Unicode can be found in [Glossary].
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Information on the Unicode character encoding model can be found in
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[CharModel].
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Zeilenga Standards Track [Page 2]
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RFC 4514 LDAP: Distinguished Names June 2006
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2. Converting DistinguishedName from ASN.1 to a String
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X.501 [X.501] defines the ASN.1 [X.680] structure of distinguished
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name. The following is a variant provided for discussion purposes.
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DistinguishedName ::= RDNSequence
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RDNSequence ::= SEQUENCE OF RelativeDistinguishedName
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RelativeDistinguishedName ::= SET SIZE (1..MAX) OF
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AttributeTypeAndValue
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AttributeTypeAndValue ::= SEQUENCE {
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type AttributeType,
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value AttributeValue }
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This section defines the RECOMMENDED algorithm for converting a
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distinguished name from an ASN.1-structured representation to a UTF-8
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[RFC3629] encoded Unicode [Unicode] character string representation.
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Other documents may describe other algorithms for converting a
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distinguished name to a string, but only strings that conform to the
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grammar defined in Section 3 SHALL be produced by LDAP
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implementations.
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2.1. Converting the RDNSequence
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If the RDNSequence is an empty sequence, the result is the empty or
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zero-length string.
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Otherwise, the output consists of the string encodings of each
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RelativeDistinguishedName in the RDNSequence (according to Section
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2.2), starting with the last element of the sequence and moving
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backwards toward the first.
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The encodings of adjoining RelativeDistinguishedNames are separated
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by a comma (',' U+002C) character.
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2.2. Converting RelativeDistinguishedName
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When converting from an ASN.1 RelativeDistinguishedName to a string,
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the output consists of the string encodings of each
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AttributeTypeAndValue (according to Section 2.3), in any order.
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Where there is a multi-valued RDN, the outputs from adjoining
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AttributeTypeAndValues are separated by a plus sign ('+' U+002B)
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character.
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Zeilenga Standards Track [Page 3]
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RFC 4514 LDAP: Distinguished Names June 2006
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2.3. Converting AttributeTypeAndValue
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The AttributeTypeAndValue is encoded as the string representation of
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the AttributeType, followed by an equals sign ('=' U+003D) character,
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followed by the string representation of the AttributeValue. The
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encoding of the AttributeValue is given in Section 2.4.
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If the AttributeType is defined to have a short name (descriptor)
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[RFC4512] and that short name is known to be registered [REGISTRY]
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[RFC4520] as identifying the AttributeType, that short name, a
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<descr>, is used. Otherwise the AttributeType is encoded as the
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dotted-decimal encoding, a <numericoid>, of its OBJECT IDENTIFIER.
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The <descr> and <numericoid> are defined in [RFC4512].
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Implementations are not expected to dynamically update their
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knowledge of registered short names. However, implementations SHOULD
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provide a mechanism to allow their knowledge of registered short
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names to be updated.
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2.4. Converting an AttributeValue from ASN.1 to a String
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If the AttributeType is of the dotted-decimal form, the
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AttributeValue is represented by an number sign ('#' U+0023)
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character followed by the hexadecimal encoding of each of the octets
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of the BER encoding of the X.500 AttributeValue. This form is also
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used when the syntax of the AttributeValue does not have an LDAP-
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specific ([RFC4517], Section 3.1) string encoding defined for it, or
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the LDAP-specific string encoding is not restricted to UTF-8-encoded
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Unicode characters. This form may also be used in other cases, such
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as when a reversible string representation is desired (see Section
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5.2).
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Otherwise, if the AttributeValue is of a syntax that has a LDAP-
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specific string encoding, the value is converted first to a UTF-8-
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encoded Unicode string according to its syntax specification (see
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[RFC4517], Section 3.3, for examples). If that UTF-8-encoded Unicode
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string does not have any of the following characters that need
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escaping, then that string can be used as the string representation
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of the value.
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- a space (' ' U+0020) or number sign ('#' U+0023) occurring at
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the beginning of the string;
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- a space (' ' U+0020) character occurring at the end of the
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string;
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Zeilenga Standards Track [Page 4]
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RFC 4514 LDAP: Distinguished Names June 2006
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- one of the characters '"', '+', ',', ';', '<', '>', or '\'
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(U+0022, U+002B, U+002C, U+003B, U+003C, U+003E, or U+005C,
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respectively);
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- the null (U+0000) character.
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Other characters may be escaped.
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Each octet of the character to be escaped is replaced by a backslash
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and two hex digits, which form a single octet in the code of the
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character. Alternatively, if and only if the character to be escaped
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is one of
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' ', '"', '#', '+', ',', ';', '<', '=', '>', or '\'
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(U+0020, U+0022, U+0023, U+002B, U+002C, U+003B,
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U+003C, U+003D, U+003E, U+005C, respectively)
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it can be prefixed by a backslash ('\' U+005C).
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Examples of the escaping mechanism are shown in Section 4.
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3. Parsing a String Back to a Distinguished Name
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The string representation of Distinguished Names is restricted to
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UTF-8 [RFC3629] encoded Unicode [Unicode] characters. The structure
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of this string representation is specified using the following
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Augmented BNF [RFC4234] grammar:
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distinguishedName = [ relativeDistinguishedName
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*( COMMA relativeDistinguishedName ) ]
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relativeDistinguishedName = attributeTypeAndValue
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*( PLUS attributeTypeAndValue )
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attributeTypeAndValue = attributeType EQUALS attributeValue
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attributeType = descr / numericoid
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attributeValue = string / hexstring
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; The following characters are to be escaped when they appear
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; in the value to be encoded: ESC, one of <escaped>, leading
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; SHARP or SPACE, trailing SPACE, and NULL.
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string = [ ( leadchar / pair ) [ *( stringchar / pair )
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( trailchar / pair ) ] ]
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leadchar = LUTF1 / UTFMB
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LUTF1 = %x01-1F / %x21 / %x24-2A / %x2D-3A /
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%x3D / %x3F-5B / %x5D-7F
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trailchar = TUTF1 / UTFMB
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TUTF1 = %x01-1F / %x21 / %x23-2A / %x2D-3A /
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Zeilenga Standards Track [Page 5]
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RFC 4514 LDAP: Distinguished Names June 2006
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%x3D / %x3F-5B / %x5D-7F
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stringchar = SUTF1 / UTFMB
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SUTF1 = %x01-21 / %x23-2A / %x2D-3A /
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%x3D / %x3F-5B / %x5D-7F
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pair = ESC ( ESC / special / hexpair )
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special = escaped / SPACE / SHARP / EQUALS
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escaped = DQUOTE / PLUS / COMMA / SEMI / LANGLE / RANGLE
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hexstring = SHARP 1*hexpair
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hexpair = HEX HEX
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where the productions <descr>, <numericoid>, <COMMA>, <DQUOTE>,
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<EQUALS>, <ESC>, <HEX>, <LANGLE>, <NULL>, <PLUS>, <RANGLE>, <SEMI>,
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<SPACE>, <SHARP>, and <UTFMB> are defined in [RFC4512].
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Each <attributeType>, either a <descr> or a <numericoid>, refers to
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an attribute type of an attribute value assertion (AVA). The
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<attributeType> is followed by an <EQUALS> and an <attributeValue>.
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The <attributeValue> is either in <string> or <hexstring> form.
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If in <string> form, a LDAP string representation asserted value can
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be obtained by replacing (left to right, non-recursively) each <pair>
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appearing in the <string> as follows:
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replace <ESC><ESC> with <ESC>;
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replace <ESC><special> with <special>;
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replace <ESC><hexpair> with the octet indicated by the <hexpair>.
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If in <hexstring> form, a BER representation can be obtained from
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converting each <hexpair> of the <hexstring> to the octet indicated
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by the <hexpair>.
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There is one or more attribute value assertions, separated by <PLUS>,
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for a relative distinguished name.
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There is zero or more relative distinguished names, separated by
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<COMMA>, for a distinguished name.
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Implementations MUST recognize AttributeType name strings
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(descriptors) listed in the following table, but MAY recognize other
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name strings.
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Zeilenga Standards Track [Page 6]
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RFC 4514 LDAP: Distinguished Names June 2006
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String X.500 AttributeType
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------ --------------------------------------------
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CN commonName (2.5.4.3)
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L localityName (2.5.4.7)
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ST stateOrProvinceName (2.5.4.8)
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O organizationName (2.5.4.10)
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OU organizationalUnitName (2.5.4.11)
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C countryName (2.5.4.6)
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STREET streetAddress (2.5.4.9)
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DC domainComponent (0.9.2342.19200300.100.1.25)
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UID userId (0.9.2342.19200300.100.1.1)
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These attribute types are described in [RFC4519].
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Implementations MAY recognize other DN string representations.
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|||
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However, as there is no requirement that alternative DN string
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|||
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representations be recognized (and, if so, how), implementations
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SHOULD only generate DN strings in accordance with Section 2 of this
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document.
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4. Examples
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|||
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This notation is designed to be convenient for common forms of name.
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This section gives a few examples of distinguished names written
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using this notation. First is a name containing three relative
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distinguished names (RDNs):
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UID=jsmith,DC=example,DC=net
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Here is an example of a name containing three RDNs, in which the
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first RDN is multi-valued:
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OU=Sales+CN=J. Smith,DC=example,DC=net
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This example shows the method of escaping of a special characters
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appearing in a common name:
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CN=James \"Jim\" Smith\, III,DC=example,DC=net
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The following shows the method for encoding a value that contains a
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carriage return character:
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CN=Before\0dAfter,DC=example,DC=net
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In this RDN example, the type in the RDN is unrecognized, and the
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value is the BER encoding of an OCTET STRING containing two octets,
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0x48 and 0x69.
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|||
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|||
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|||
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|
|||
|
|
|||
|
Zeilenga Standards Track [Page 7]
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|
|
|||
|
RFC 4514 LDAP: Distinguished Names June 2006
|
|||
|
|
|||
|
|
|||
|
1.3.6.1.4.1.1466.0=#04024869
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Finally, this example shows an RDN whose commonName value consists of
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|||
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5 letters:
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|||
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|||
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Unicode Character Code UTF-8 Escaped
|
|||
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------------------------------- ------ ------ --------
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|||
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LATIN CAPITAL LETTER L U+004C 0x4C L
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LATIN SMALL LETTER U U+0075 0x75 u
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LATIN SMALL LETTER C WITH CARON U+010D 0xC48D \C4\8D
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LATIN SMALL LETTER I U+0069 0x69 i
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LATIN SMALL LETTER C WITH ACUTE U+0107 0xC487 \C4\87
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|||
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This could be encoded in printable ASCII [ASCII] (useful for
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|||
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debugging purposes) as:
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|||
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|||
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CN=Lu\C4\8Di\C4\87
|
|||
|
|
|||
|
5. Security Considerations
|
|||
|
|
|||
|
The following security considerations are specific to the handling of
|
|||
|
distinguished names. LDAP security considerations are discussed in
|
|||
|
[RFC4511] and other documents comprising the LDAP Technical
|
|||
|
Specification [RFC4510].
|
|||
|
|
|||
|
5.1. Disclosure
|
|||
|
|
|||
|
Distinguished Names typically consist of descriptive information
|
|||
|
about the entries they name, which can be people, organizations,
|
|||
|
devices, or other real-world objects. This frequently includes some
|
|||
|
of the following kinds of information:
|
|||
|
|
|||
|
- the common name of the object (i.e., a person's full name)
|
|||
|
- an email or TCP/IP address
|
|||
|
- its physical location (country, locality, city, street address)
|
|||
|
- organizational attributes (such as department name or
|
|||
|
affiliation)
|
|||
|
|
|||
|
In some cases, such information can be considered sensitive. In many
|
|||
|
countries, privacy laws exist that prohibit disclosure of certain
|
|||
|
kinds of descriptive information (e.g., email addresses). Hence,
|
|||
|
server implementers are encouraged to support Directory Information
|
|||
|
Tree (DIT) structural rules and name forms [RFC4512], as these
|
|||
|
provide a mechanism for administrators to select appropriate naming
|
|||
|
attributes for entries. Administrators are encouraged to use
|
|||
|
mechanisms, access controls, and other administrative controls that
|
|||
|
may be available to restrict use of attributes containing sensitive
|
|||
|
information in naming of entries. Additionally, use of
|
|||
|
|
|||
|
|
|||
|
|
|||
|
Zeilenga Standards Track [Page 8]
|
|||
|
|
|||
|
RFC 4514 LDAP: Distinguished Names June 2006
|
|||
|
|
|||
|
|
|||
|
authentication and data security services in LDAP [RFC4513][RFC4511]
|
|||
|
should be considered.
|
|||
|
|
|||
|
5.2. Use of Distinguished Names in Security Applications
|
|||
|
|
|||
|
The transformations of an AttributeValue value from its X.501 form to
|
|||
|
an LDAP string representation are not always reversible back to the
|
|||
|
same BER (Basic Encoding Rules) or DER (Distinguished Encoding Rules)
|
|||
|
form. An example of a situation that requires the DER form of a
|
|||
|
distinguished name is the verification of an X.509 certificate.
|
|||
|
|
|||
|
For example, a distinguished name consisting of one RDN with one AVA,
|
|||
|
in which the type is commonName and the value is of the TeletexString
|
|||
|
choice with the letters 'Sam', would be represented in LDAP as the
|
|||
|
string <CN=Sam>. Another distinguished name in which the value is
|
|||
|
still 'Sam', but is of the PrintableString choice, would have the
|
|||
|
same representation <CN=Sam>.
|
|||
|
|
|||
|
Applications that require the reconstruction of the DER form of the
|
|||
|
value SHOULD NOT use the string representation of attribute syntaxes
|
|||
|
when converting a distinguished name to the LDAP format. Instead,
|
|||
|
they SHOULD use the hexadecimal form prefixed by the number sign ('#'
|
|||
|
U+0023) as described in the first paragraph of Section 2.4.
|
|||
|
|
|||
|
6. Acknowledgements
|
|||
|
|
|||
|
This document is an update to RFC 2253, by Mark Wahl, Tim Howes, and
|
|||
|
Steve Kille. RFC 2253 was a product of the IETF ASID Working Group.
|
|||
|
|
|||
|
This document is a product of the IETF LDAPBIS Working Group.
|
|||
|
|
|||
|
7. References
|
|||
|
|
|||
|
7.1. Normative References
|
|||
|
|
|||
|
[REGISTRY] IANA, Object Identifier Descriptors Registry,
|
|||
|
<http://www.iana.org/assignments/ldap-parameters>.
|
|||
|
|
|||
|
[Unicode] The Unicode Consortium, "The Unicode Standard, Version
|
|||
|
3.2.0" is defined by "The Unicode Standard, Version
|
|||
|
3.0" (Reading, MA, Addison-Wesley, 2000. ISBN 0-201-
|
|||
|
61633-5), as amended by the "Unicode Standard Annex
|
|||
|
#27: Unicode 3.1"
|
|||
|
(http://www.unicode.org/reports/tr27/) and by the
|
|||
|
"Unicode Standard Annex #28: Unicode 3.2"
|
|||
|
(http://www.unicode.org/reports/tr28/).
|
|||
|
|
|||
|
|
|||
|
|
|||
|
|
|||
|
|
|||
|
Zeilenga Standards Track [Page 9]
|
|||
|
|
|||
|
RFC 4514 LDAP: Distinguished Names June 2006
|
|||
|
|
|||
|
|
|||
|
[X.501] International Telecommunication Union -
|
|||
|
Telecommunication Standardization Sector, "The
|
|||
|
Directory -- Models," X.501(1993) (also ISO/IEC 9594-
|
|||
|
2:1994).
|
|||
|
|
|||
|
[X.680] International Telecommunication Union -
|
|||
|
Telecommunication Standardization Sector, "Abstract
|
|||
|
Syntax Notation One (ASN.1) - Specification of Basic
|
|||
|
Notation", X.680(1997) (also ISO/IEC 8824-1:1998).
|
|||
|
|
|||
|
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
|
|||
|
Requirement Levels", BCP 14, RFC 2119, March 1997.
|
|||
|
|
|||
|
[RFC3629] Yergeau, F., "UTF-8, a transformation format of ISO
|
|||
|
10646", STD 63, RFC 3629, November 2003.
|
|||
|
|
|||
|
[RFC4234] Crocker, D. and P. Overell, "Augmented BNF for Syntax
|
|||
|
Specifications: ABNF", RFC 4234, October 2005.
|
|||
|
|
|||
|
[RFC4510] Zeilenga, K., Ed., "Lightweight Directory Access
|
|||
|
Protocol (LDAP): Technical Specification Road Map", RFC
|
|||
|
4510, June 2006.
|
|||
|
|
|||
|
[RFC4511] Sermersheim, J., Ed., "Lightweight Directory Access
|
|||
|
Protocol (LDAP): The Protocol", RFC 4511, June 2006.
|
|||
|
|
|||
|
[RFC4512] Zeilenga, K., "Lightweight Directory Access Protocol
|
|||
|
(LDAP): Directory Information Models", RFC 4512, June
|
|||
|
2006.
|
|||
|
|
|||
|
[RFC4513] Harrison, R., Ed., "Lightweight Directory Access
|
|||
|
Protocol (LDAP): Authentication Methods and Security
|
|||
|
Mechanisms", RFC 4513, June 2006.
|
|||
|
|
|||
|
[RFC4517] Legg, S., Ed., "Lightweight Directory Access Protocol
|
|||
|
(LDAP): Syntaxes and Matching Rules", RFC 4517, June
|
|||
|
2006.
|
|||
|
|
|||
|
[RFC4519] Sciberras, A., Ed., "Lightweight Directory Access
|
|||
|
Protocol (LDAP): Schema for User Applications", RFC
|
|||
|
4519, June 2006.
|
|||
|
|
|||
|
[RFC4520] Zeilenga, K., "Internet Assigned Numbers Authority
|
|||
|
(IANA) Considerations for the Lightweight Directory
|
|||
|
Access Protocol (LDAP)", BCP 64, RFC 4520, June 2006.
|
|||
|
|
|||
|
|
|||
|
|
|||
|
|
|||
|
|
|||
|
|
|||
|
Zeilenga Standards Track [Page 10]
|
|||
|
|
|||
|
RFC 4514 LDAP: Distinguished Names June 2006
|
|||
|
|
|||
|
|
|||
|
7.2. Informative References
|
|||
|
|
|||
|
[ASCII] Coded Character Set--7-bit American Standard Code for
|
|||
|
Information Interchange, ANSI X3.4-1986.
|
|||
|
|
|||
|
[CharModel] Whistler, K. and M. Davis, "Unicode Technical Report
|
|||
|
#17, Character Encoding Model", UTR17,
|
|||
|
<http://www.unicode.org/unicode/reports/tr17/>, August
|
|||
|
2000.
|
|||
|
|
|||
|
[Glossary] The Unicode Consortium, "Unicode Glossary",
|
|||
|
<http://www.unicode.org/glossary/>.
|
|||
|
|
|||
|
[X.500] International Telecommunication Union -
|
|||
|
Telecommunication Standardization Sector, "The
|
|||
|
Directory -- Overview of concepts, models and
|
|||
|
services," X.500(1993) (also ISO/IEC 9594-1:1994).
|
|||
|
|
|||
|
[X.511] International Telecommunication Union -
|
|||
|
Telecommunication Standardization Sector, "The
|
|||
|
Directory: Abstract Service Definition", X.511(1993)
|
|||
|
(also ISO/IEC 9594-3:1993).
|
|||
|
|
|||
|
[X.690] International Telecommunication Union -
|
|||
|
Telecommunication Standardization Sector,
|
|||
|
"Specification of ASN.1 encoding rules: Basic Encoding
|
|||
|
Rules (BER), Canonical Encoding Rules (CER), and
|
|||
|
Distinguished Encoding Rules (DER)", X.690(1997) (also
|
|||
|
ISO/IEC 8825-1:1998).
|
|||
|
|
|||
|
[RFC2849] Good, G., "The LDAP Data Interchange Format (LDIF) -
|
|||
|
Technical Specification", RFC 2849, June 2000.
|
|||
|
|
|||
|
|
|||
|
|
|||
|
|
|||
|
|
|||
|
|
|||
|
|
|||
|
|
|||
|
|
|||
|
|
|||
|
|
|||
|
|
|||
|
|
|||
|
|
|||
|
|
|||
|
|
|||
|
|
|||
|
|
|||
|
|
|||
|
Zeilenga Standards Track [Page 11]
|
|||
|
|
|||
|
RFC 4514 LDAP: Distinguished Names June 2006
|
|||
|
|
|||
|
|
|||
|
Appendix A. Presentation Issues
|
|||
|
|
|||
|
This appendix is provided for informational purposes only; it is not
|
|||
|
a normative part of this specification.
|
|||
|
|
|||
|
The string representation described in this document is not intended
|
|||
|
to be presented to humans without translation. However, at times it
|
|||
|
may be desirable to present non-translated DN strings to users. This
|
|||
|
section discusses presentation issues associated with non-translated
|
|||
|
DN strings. Issues with presentation of translated DN strings are
|
|||
|
not discussed in this appendix. Transcoding issues are also not
|
|||
|
discussed in this appendix.
|
|||
|
|
|||
|
This appendix provides guidance for applications presenting DN
|
|||
|
strings to users. This section is not comprehensive; it does not
|
|||
|
discuss all presentation issues that implementers may face.
|
|||
|
|
|||
|
Not all user interfaces are capable of displaying the full set of
|
|||
|
Unicode characters. Some Unicode characters are not displayable.
|
|||
|
|
|||
|
It is recommended that human interfaces use the optional hex pair
|
|||
|
escaping mechanism (Section 2.3) to produce a string representation
|
|||
|
suitable for display to the user. For example, an application can
|
|||
|
generate a DN string for display that escapes all non-printable
|
|||
|
characters appearing in the AttributeValue's string representation
|
|||
|
(as demonstrated in the final example of Section 4).
|
|||
|
|
|||
|
When a DN string is displayed in free-form text, it is often
|
|||
|
necessary to distinguish the DN string from surrounding text. While
|
|||
|
this is often done with whitespace (as demonstrated in Section 4), it
|
|||
|
is noted that DN strings may end with whitespace. Careful readers of
|
|||
|
Section 3 will note that the characters '<' (U+003C) and '>' (U+003E)
|
|||
|
may only appear in the DN string if escaped. These characters are
|
|||
|
intended to be used in free-form text to distinguish a DN string from
|
|||
|
surrounding text. For example, <CN=Sam\ > distinguishes the string
|
|||
|
representation of the DN composed of one RDN consisting of the AVA
|
|||
|
(the commonName (CN) value 'Sam ') from the surrounding text. It
|
|||
|
should be noted to the user that the wrapping '<' and '>' characters
|
|||
|
are not part of the DN string.
|
|||
|
|
|||
|
DN strings can be quite long. It is often desirable to line-wrap
|
|||
|
overly long DN strings in presentations. Line wrapping should be
|
|||
|
done by inserting whitespace after the RDN separator character or, if
|
|||
|
necessary, after the AVA separator character. It should be noted to
|
|||
|
the user that the inserted whitespace is not part of the DN string
|
|||
|
and is to be removed before use in LDAP. For example, the following
|
|||
|
DN string is long:
|
|||
|
|
|||
|
|
|||
|
|
|||
|
|
|||
|
Zeilenga Standards Track [Page 12]
|
|||
|
|
|||
|
RFC 4514 LDAP: Distinguished Names June 2006
|
|||
|
|
|||
|
|
|||
|
CN=Kurt D. Zeilenga,OU=Engineering,L=Redwood Shores,
|
|||
|
O=OpenLDAP Foundation,ST=California,C=US
|
|||
|
|
|||
|
So it has been line-wrapped for readability. The extra whitespace is
|
|||
|
to be removed before the DN string is used in LDAP.
|
|||
|
|
|||
|
Inserting whitespace is not advised because it may not be obvious to
|
|||
|
the user which whitespace is part of the DN string and which
|
|||
|
whitespace was added for readability.
|
|||
|
|
|||
|
Another alternative is to use the LDAP Data Interchange Format (LDIF)
|
|||
|
[RFC2849]. For example:
|
|||
|
|
|||
|
# This entry has a long DN...
|
|||
|
dn: CN=Kurt D. Zeilenga,OU=Engineering,L=Redwood Shores,
|
|||
|
O=OpenLDAP Foundation,ST=California,C=US
|
|||
|
CN: Kurt D. Zeilenga
|
|||
|
SN: Zeilenga
|
|||
|
objectClass: person
|
|||
|
|
|||
|
Appendix B. Changes Made since RFC 2253
|
|||
|
|
|||
|
This appendix is provided for informational purposes only, it is not
|
|||
|
a normative part of this specification.
|
|||
|
|
|||
|
The following substantive changes were made to RFC 2253:
|
|||
|
|
|||
|
- Removed IESG Note. The IESG Note has been addressed.
|
|||
|
- Replaced all references to ISO 10646-1 with [Unicode].
|
|||
|
- Clarified (in Section 1) that this document does not define a
|
|||
|
canonical string representation.
|
|||
|
- Clarified that Section 2 describes the RECOMMENDED encoding
|
|||
|
algorithm and that alternative algorithms are allowed. Some
|
|||
|
encoding options described in RFC 2253 are now treated as
|
|||
|
alternative algorithms in this specification.
|
|||
|
- Revised specification (in Section 2) to allow short names of any
|
|||
|
registered attribute type to appear in string representations of
|
|||
|
DNs instead of being restricted to a "published table". Removed
|
|||
|
"as an example" language. Added statement (in Section 3)
|
|||
|
allowing recognition of additional names but require recognition
|
|||
|
of those names in the published table. The table now appears in
|
|||
|
Section 3.
|
|||
|
- Removed specification of additional requirements for LDAPv2
|
|||
|
implementations which also support LDAPv3 (RFC 2253, Section 4)
|
|||
|
as LDAPv2 is now Historic.
|
|||
|
- Allowed recognition of alternative string representations.
|
|||
|
- Updated Section 2.4 to allow hex pair escaping of all characters
|
|||
|
and clarified escaping for when multiple octet UTF-8 encodings
|
|||
|
|
|||
|
|
|||
|
|
|||
|
Zeilenga Standards Track [Page 13]
|
|||
|
|
|||
|
RFC 4514 LDAP: Distinguished Names June 2006
|
|||
|
|
|||
|
|
|||
|
are present. Indicated that null (U+0000) character is to be
|
|||
|
escaped. Indicated that equals sign ('=' U+003D) character may
|
|||
|
be escaped as '\='.
|
|||
|
- Rewrote Section 3 to use ABNF as defined in RFC 4234.
|
|||
|
- Updated the Section 3 ABNF. Changes include:
|
|||
|
+ allowed AttributeType short names of length 1 (e.g., 'L'),
|
|||
|
+ used more restrictive <oid> production in AttributeTypes,
|
|||
|
+ did not require escaping of equals sign ('=' U+003D)
|
|||
|
characters,
|
|||
|
+ did not require escaping of non-leading number sign ('#'
|
|||
|
U+0023) characters,
|
|||
|
+ allowed space (' ' U+0020) to be escaped as '\ ',
|
|||
|
+ required hex escaping of null (U+0000) characters, and
|
|||
|
+ removed LDAPv2-only constructs.
|
|||
|
- Updated Section 3 to describe how to parse elements of the
|
|||
|
grammar.
|
|||
|
- Rewrote examples.
|
|||
|
- Added reference to documentations containing general LDAP
|
|||
|
security considerations.
|
|||
|
- Added discussion of presentation issues (Appendix A).
|
|||
|
- Added this appendix.
|
|||
|
|
|||
|
In addition, numerous editorial changes were made.
|
|||
|
|
|||
|
Editor's Address
|
|||
|
|
|||
|
Kurt D. Zeilenga
|
|||
|
OpenLDAP Foundation
|
|||
|
|
|||
|
EMail: Kurt@OpenLDAP.org
|
|||
|
|
|||
|
|
|||
|
|
|||
|
|
|||
|
|
|||
|
|
|||
|
|
|||
|
|
|||
|
|
|||
|
|
|||
|
|
|||
|
|
|||
|
|
|||
|
|
|||
|
|
|||
|
|
|||
|
|
|||
|
|
|||
|
|
|||
|
|
|||
|
|
|||
|
Zeilenga Standards Track [Page 14]
|
|||
|
|
|||
|
RFC 4514 LDAP: Distinguished Names June 2006
|
|||
|
|
|||
|
|
|||
|
Full Copyright Statement
|
|||
|
|
|||
|
Copyright (C) The Internet Society (2006).
|
|||
|
|
|||
|
This document is subject to the rights, licenses and restrictions
|
|||
|
contained in BCP 78, and except as set forth therein, the authors
|
|||
|
retain all their rights.
|
|||
|
|
|||
|
This document and the information contained herein are provided on an
|
|||
|
"AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE REPRESENTS
|
|||
|
OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY AND THE INTERNET
|
|||
|
ENGINEERING TASK FORCE DISCLAIM ALL WARRANTIES, EXPRESS OR IMPLIED,
|
|||
|
INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE
|
|||
|
INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED
|
|||
|
WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.
|
|||
|
|
|||
|
Intellectual Property
|
|||
|
|
|||
|
The IETF takes no position regarding the validity or scope of any
|
|||
|
Intellectual Property Rights or other rights that might be claimed to
|
|||
|
pertain to the implementation or use of the technology described in
|
|||
|
this document or the extent to which any license under such rights
|
|||
|
might or might not be available; nor does it represent that it has
|
|||
|
made any independent effort to identify any such rights. Information
|
|||
|
on the procedures with respect to rights in RFC documents can be
|
|||
|
found in BCP 78 and BCP 79.
|
|||
|
|
|||
|
Copies of IPR disclosures made to the IETF Secretariat and any
|
|||
|
assurances of licenses to be made available, or the result of an
|
|||
|
attempt made to obtain a general license or permission for the use of
|
|||
|
such proprietary rights by implementers or users of this
|
|||
|
specification can be obtained from the IETF on-line IPR repository at
|
|||
|
http://www.ietf.org/ipr.
|
|||
|
|
|||
|
The IETF invites any interested party to bring to its attention any
|
|||
|
copyrights, patents or patent applications, or other proprietary
|
|||
|
rights that may cover technology that may be required to implement
|
|||
|
this standard. Please address the information to the IETF at
|
|||
|
ietf-ipr@ietf.org.
|
|||
|
|
|||
|
Acknowledgement
|
|||
|
|
|||
|
Funding for the RFC Editor function is provided by the IETF
|
|||
|
Administrative Support Activity (IASA).
|
|||
|
|
|||
|
|
|||
|
|
|||
|
|
|||
|
|
|||
|
|
|||
|
|
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Zeilenga Standards Track [Page 15]
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