Re: [pkix] Amendment to CABF Baseline Requirements

Rob Stradling <rob.stradling@comodo.com> Fri, 07 April 2017 12:54 UTC

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To: Russ Housley <housley@vigilsec.com>, Ben Wilson <ben.wilson@digicert.com>
References: <906f1c1dde4f44789646197d887da312@EX2.corp.digicert.com> <a24a24b9-542c-a619-3445-47e812f9c46b@nthpermutation.com> <27e9bc684735472bbd6d7f82b5e2823b@EX2.corp.digicert.com> <662C0D5C-EF34-4BD1-B3BC-B7B9A84B4990@vigilsec.com>
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From: Rob Stradling <rob.stradling@comodo.com>
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Date: Fri, 7 Apr 2017 13:54:20 +0100
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Subject: Re: [pkix] Amendment to CABF Baseline Requirements
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Russ, RFC5280 includes all of the following:

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

The *-name upper bounds apply to X.500 DNs, whereas IINM the 
*-name-length upper bounds apply to the x400Address GeneralName type.

On 06/04/17 20:24, Russ Housley wrote:
> 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

-- 
Rob Stradling
Senior Research & Development Scientist
COMODO - Creating Trust Online