Lightweight Directory Access Protocol (LDAP): The Binary Encoding Option
RFC 4522

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Network Working Group                                            S. Legg
Request for Comments: 4522                                       eB2Bcom
Category: Standards Track                                      June 2006

             Lightweight Directory Access Protocol (LDAP):
                       The Binary Encoding Option

Status of This Memo

   This document specifies an Internet standards track protocol for the
   Internet community, and requests discussion and suggestions for
   improvements.  Please refer to the current edition of the "Internet
   Official Protocol Standards" (STD 1) for the standardization state
   and status of this protocol.  Distribution of this memo is unlimited.

Copyright Notice

   Copyright (C) The Internet Society (2006).

Abstract

   Each attribute stored in a Lightweight Directory Access Protocol
   (LDAP) directory has a defined syntax (i.e., data type).  A syntax
   definition specifies how attribute values conforming to the syntax
   are normally represented when transferred in LDAP operations.  This
   representation is referred to as the LDAP-specific encoding to
   distinguish it from other methods of encoding attribute values.  This
   document defines an attribute option, the binary option, that can be
   used to specify that the associated attribute values are instead
   encoded according to the Basic Encoding Rules (BER) used by X.500
   directories.

Table of Contents

   1. Introduction ....................................................2
   2. Conventions .....................................................2
   3. The Binary Option ...............................................2
   4. Syntaxes Requiring Binary Transfer ..............................3
   5. Attributes Returned in a Search .................................4
   6. All User Attributes .............................................4
   7. Conflicting Requests ............................................5
   8. Security Considerations .........................................5
   9. IANA Considerations .............................................5
   10. References .....................................................5
      10.1. Normative References ......................................5
      10.2. Informative References ....................................6

Legg                        Standards Track                     [Page 1]
RFC 4522            LDAP: The Binary Encoding Option           June 2006

1.  Introduction

   Each attribute stored in a Lightweight Directory Access Protocol
   (LDAP) directory [RFC4510] has a defined syntax (i.e., data type)
   which constrains the structure and format of its values.

   The description of each syntax [RFC4517] specifies how attribute or
   assertion values [RFC4512] conforming to the syntax are normally
   represented when transferred in LDAP operations [RFC4511].  This
   representation is referred to as the LDAP-specific encoding to
   distinguish it from other methods of encoding attribute values.

   This document defines an attribute option, the binary option, which
   can be used in an attribute description [RFC4512] in an LDAP
   operation to specify that the associated attribute values or
   assertion values are, or are requested to be, encoded according to
   the Basic Encoding Rules (BER) [BER] as used by X.500 [X.500]
   directories, instead of the usual LDAP-specific encoding.

   The binary option was originally defined in RFC 2251 [RFC2251].  The
   LDAP technical specification [RFC4510] has obsoleted the previously
   defined LDAP technical specification [RFC3377], which included RFC
   2251.  The binary option was not included in the revised LDAP
   technical specification for a variety of reasons including
   implementation inconsistencies.  No attempt is made here to resolve
   the known inconsistencies.

   This document reintroduces the binary option for use with certain
   attribute syntaxes, such as certificate syntax [RFC4523], that
   specifically require it.  No attempt has been made to address use of
   the binary option with attributes of syntaxes that do not require its
   use.  Unless addressed in a future specification, this use is to be
   avoided.

2.  Conventions

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
   document are to be interpreted as described in BCP 14, RFC 2119
   [BCP14].

3.  The Binary Option

   The binary option is indicated with the attribute option string
   "binary" in an attribute description.  Note that, like all attribute
   options, the string representing the binary option is case
   insensitive.

Legg                        Standards Track                     [Page 2]
RFC 4522            LDAP: The Binary Encoding Option           June 2006

   Where the binary option is present in an attribute description, the
   associated attribute values or assertion values MUST be BER encoded