Re: [pkix] Amendment to CABF Baseline Requirements

Russ Housley <housley@vigilsec.com> Thu, 06 April 2017 19:24 UTC

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From: Russ Housley <housley@vigilsec.com>
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Date: Thu, 6 Apr 2017 15:24:34 -0400
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To: Ben Wilson <ben.wilson@digicert.com>
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Subject: Re: [pkix] Amendment to CABF Baseline Requirements
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The comment in the UpperBounds ASN.1 module (the 8th edition) says:

-- EXPORTS All 
-- The types and values defined in this module are exported for use in the other ASN.1
-- modules contained within these Directory Specifications, and for the use of other
-- applications which will use them to access Directory services. Other applications
-- may use them for their own purposes, but this will not constrain extensions and
-- modifications needed to maintain or improve the Directory service.

X.509 is part of the Directory Specifications, so they are not advisory.

It looks like ITU-T increased the length of the organizational unit name in the most recent edition.

RFC 5280 says:

ub-organization-name-length INTEGER ::= 64
ub-organizational-unit-name-length INTEGER ::= 32

The UpperBounds ASN.1 module (the 8th edition) says:

ub-organization-name                       INTEGER ::= 64
ub-organizational-unit-name                INTEGER ::= 64

So, we may already be in a place where implementations conforming to X.509 will produce a certificate that cannot be decoded by an implementation that conforms to RFC 5280.

I wish we gad gotten a heads-up …

Russ



> On Apr 6, 2017, at 2:55 PM, Ben Wilson <ben.wilson@digicert.com> wrote:
> 
> Thanks, Michael.    Is it relevant that Annex C to X.520 (2012) states,
> "(This annex does not form an integral part of this Recommendation |
> International Standard.)" whereas before (1988) it stated,  "This Annex is
> part of the Recommendation."?
> 
> From: pkix [mailto:pkix-bounces@ietf.org] On Behalf Of Michael StJohns
> Sent: Thursday, April 6, 2017 10:55 AM
> To: pkix@ietf.org
> Subject: Re: [pkix] Amendment to CABF Baseline Requirements
> 
> Hi Ben - 
> 
> IETF 5280 et al are profiles of the X.509 documents.  The upper length
> bounds for orgnaizationName and commonName fields in 5280 is no different
> than the upper bounds specified in X.509 (at least as of the 2014
> document).  I would suggest that you will pretty much break any and all
> implementations of X.509 clients that rely or enforce this limit as well as
> any code that generates certificate requests.
> 
> I will note that overloading text fields with structured data is generally
> not a good idea - as you've found.  
> 
> Mike
> 
> 
> 
> On 4/6/2017 12:24 PM, Ben Wilson wrote:
> Does anyone want to comment on my draft amendment to the CA/Browser Forum’s
> Baseline Requirements for SSL/TLS Certificates which would remove the
> 64-character limit on the commonName and organizationName,  as an exception
> to RFC 5280?  The text of the relevant Baseline Requirement provision is
> found below with the proposed additional language in ALL CAPS.  The reason
> for the first change (commonName) is there are FQDNs (in Subject Alternative
> Names) that are longer than 64 characters.  The reason for the second change
> (organizationName) is that there are organizations with names longer than 64
> characters.
>  
> 7.1.4.2.2.             Subject Distinguished Name Fields
> a.            Certificate Field: subject:commonName (OID 2.5.4.3)  
> Required/Optional: Deprecated (Discouraged, but not prohibited)
> Contents: If present, this field MUST contain a single IP address or
> Fully-Qualified Domain Name that is one of the values contained in the
> Certificate’s subjectAltName extension (see Section 7.1.4.2.1).
> MAXIMUM LENGTH:  NO STIPULATION.  (THIS IS AN EXCEPTION TO RFC 5280 WHICH
> SPECIFIES AN UPPER BOUND OF 64 CHARACTERS.)
> b.            Certificate Field: subject:organizationName (OID 2.5.4.10)
> Optional.  
> Contents: If present, the subject:organizationName field MUST contain either
> the Subject’s name or DBA as verified under Section 3.2.2.2. The CA may
> include information in this field that differs slightly from the verified
> name, such as common variations or abbreviations, provided that the CA
> documents the difference and any abbreviations used are locally accepted
> abbreviations; e.g., if the official record shows “Company Name
> Incorporated”, the CA MAY use “Company Name Inc.” or “Company Name”. 
> Because Subject name attributes for individuals (e.g. givenName (2.5.4.42)
> and surname (2.5.4.4)) are not broadly supported by application software,
> the CA MAY use the subject:organizationName field to convey a natural person
> Subject’s name or DBA.
> MAXIMUM LENGTH:  256 CHARACTERS (THIS IS AN EXCEPTION TO RFC 5280 WHICH
> SPECIFIES AN UPPER BOUND OF 64 CHARACTERS.)
>  
> Thanks,
> Ben Wilson
> 
> 
> 
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