A plan for PKIX, LDAPv3, and ;binary

[wpolk@nist.gov (by way of "Kurt D. Zeilenga" <Kurt@OpenLDAP.org>)]

[resent to hit both lists -Kdz]

Folks,

Three of the four Chairs (Tim Polk, Bob Morgan, Kurt Zeilenga) of the LDAPbis 
and PKIX WGs and one of the document authors (Steven Legg) met  in Atlanta to 
discuss LDAPv3 ­ PKIX issues, and we have a way forward regarding X.509 
certificate schema and ;binary transfer option.

The PKIX WG will draft a new technical specification describing the 
Certificate, Certificate List and Certificate Pair syntaxes, the value 
preservation requirements for attributes of these syntaxes, and the ;binary 
transfer option used in requesting and transferring attributes of these 
syntaxes.  (Attributes of these syntaxes include userCerificate, cACertificate, 
certificateRevocationList, authorityRevocationList, and crossCertificatePair.)  
The LDAPbis WG will provide any support the PKIX WG requires/requests.

(1) Upon review of the PKIX-LDAP ?survey? we see a critical mass of PKI clients 
and LDAP servers that achieve interoperability using LDAPv3 with the ;binary 
option.  As these clients appear to be in the majority, we believe the best 
approach is to maintain this option for the transfer of X.509 certificates and 
CRLs.  Since this is the behavior documented in RFCs 2251, 2252, and 2256 (as 
well as the overarching 3377) this will require the least changes to the LDAPv3 
specifications as well.

(2) Per previous LDAPBIS discussions, the ;binary option need not be maintained 
as a general-purpose LDAP feature.  There is no need to hold up PKIX syntax and 
schema for LDAPBIS to define the general behavior of that feature.  This option 
will be defined in the PKIX syntax and schema document.

(3) The ;binary option as originally defined did not fully meet PKIX 
requirements anyway.  The real requirements are that these attribute values (a) 
be stored on the server in the same form that it was received in; and (b) are 
returned to the requester in the same form as received.  The PKIX syntax and 
schema for LDAPv3 will impose these new value preservation requirements on LDAP 
servers; this is consistent with the current LDAPBIS ?Directory Information 
Models? draft.

(4) The lack of a defined LDAP-specific encoding for Certificate, Certificate 
List and Certificate Pair syntaxes is a problem, as a small percentage of 
implementations transfer these attributes without the ;binary option.  Rather 
than be silent, we suggest that the PKIX syntax and schema document state the 
LDAP-specific encoding used in transfer without the ;binary option but 
deprecate its use.  This LDAP-specific encoding has the same transfer 
representation as when the attribute is transferred with the ;binary option.

We believe this represents a straightforward path forward that meets the PKIX 
interoperability requirements while being most compatible with current PKI 
behavior, current LDAPv3 standards, and upcoming LDAPBIS documents.

Thank you,

Tim Polk, RL "Bob" Morgan, Kurt Zeilenga, and Steven Legg