[cabfpub] Definition of an SSL certificate

Fri Jan 3 21:58:28 UTC 2014

On 03/01/14 21:09, Moudrick M. Dadashov wrote:
> On 1/3/2014 9:32 PM, Jeremy Rowley wrote:
>>
>> Sorry – I got the discussion a bit off-track. The issue is not whether
>> domain names are vetted, but the fact that the BRs do not clearly
>> define what certs are covered. There is a significant gray area on
>> when certificates are exempt from the BRs.
>>
>> If requiring the BR/EV OID is not a possibility, I’d define the scope
>> as any certificate that either (i) specifies a domain name in the CN
>> field or subjectAltName extension and includes the anyEKU or
>> serverAuth or omits an EKU or (ii) is intended to enable SSL/TLS, as
>> evidenced by inclusion of the serverAuth EKU.
>>
> Once again, relying on BR/EV OID would be really good solution.
>
> Jeremy, to my understanding RFC 5280 accepts anyEKU only in combination
> with any other EKU but not as the only EKU:
>
> “Certificates using applications MAY require that the extended key usage
> extension be present and that a particular purpose be indicated in order
> for the certificate to be acceptable to that application.

But RFC5280 also says:
   "Applications that require the presence of a
    particular purpose MAY reject certificates that include the
    anyExtendedKeyUsage OID but not the particular OID expected for the
    application.

That's MAY, not MUST.

> If a CA includes extended key usages to satisfy such applications, but
> does not wish to restrict usages of the key, the CA can include the
> special KeyPurposeId anyExtendedKeyUsage ***in addition to the
> particular key purposes required by the applications***.
>
> So based on this:
> SSL server: = SAN + serverAuth + [anyEKU+EKU]
> SSL client:= [SAN] +clientAuth + [anyEKU+EKU]
>
> Thanks,
> M.D.
>
>> Although the definition needs word smithing, it captures the
>> certificates of primary concern (those containing domain names)
>> without excluding internal server name certs. Thoughts?
>>
>> Jeremy
>>
>> *From:*Brown, Wendy (10421) [mailto:wendy.brown at protiviti.com]
>> *Sent:* Friday, January 03, 2014 12:08 PM
>> *To:* Jeremy Rowley; 'Mads Egil Henriksveen'; 'Moudrick M. Dadashov';
>> public at cabforum.org
>> *Subject:* RE: [cabfpub] Definition of an SSL certificate
>>
>> The requirement to verify is in the CP – the details of How goes in
>> the CPS.
>>
>> *From:*Jeremy Rowley [mailto:jeremy.rowley at digicert.com]
>> *Sent:* Friday, January 03, 2014 2:03 PM
>> *To:* Brown, Wendy (10421); 'Mads Egil Henriksveen'; 'Moudrick M.
>> Dadashov'; public at cabforum.org <mailto:public at cabforum.org>
>> *Subject:* RE: [cabfpub] Definition of an SSL certificate
>>
>> Thanks Wendy for the clarification.  However, I didn’t see anything
>> specifying how the CA is supposed to verify the domain.
>>
>> *From:*Brown, Wendy (10421) [mailto:wendy.brown at protiviti.com]
>> *Sent:* Friday, January 03, 2014 11:55 AM
>> *To:* Jeremy Rowley; 'Mads Egil Henriksveen'; 'Moudrick M. Dadashov';
>> public at cabforum.org <mailto:public at cabforum.org>
>> *Subject:* RE: [cabfpub] Definition of an SSL certificate
>>
>> The FBCA and Common Policy CPs actually require all information
>> included in a certificate to be verified – so that would include any
>> domain names, see 3.2.4.
>>
>> Thanks,
>>
>> Wendy
>>
>> Wendy Brown
>>
>> FPKIMA Technical Liaison
>>
>> Protiviti Government Services
>>
>> 703-299-4705 (office)    703-965-2990 (cell)
>>
>> wendy.brown at fpki.gov <mailto:wendy.brown at fpki.gov>
>>
>> wendy.brown at protiviti.com <mailto:wendy.brown at protiviti.com>
>>
>> *From:*public-bounces at cabforum.org
>> <mailto:public-bounces at cabforum.org>
>> [mailto:public-bounces at cabforum.org] *On Behalf Of *Jeremy Rowley
>> *Sent:* Friday, January 03, 2014 11:19 AM
>> *To:* 'Mads Egil Henriksveen'; 'Moudrick M. Dadashov';
>> public at cabforum.org <mailto:public at cabforum.org>
>> *Subject:* Re: [cabfpub] Definition of an SSL certificate
>>
>> Many of the trusted QC issuers (and other community issuers) are not
>> involved in the CAB Forum.  Although you are aware of the
>> requirements, I don’t think this knowledge is global. For example, I
>> don’t think the NIST CP or FBCA CP ever mentions domain validation. A
>> CA following either CP for client certs wouldn’t necessarily validate
>> an included domain.
>>
>> Jeremy
>>
>> *From:*public-bounces at cabforum.org
>> <mailto:public-bounces at cabforum.org>
>> [mailto:public-bounces at cabforum.org] *On Behalf Of *Mads Egil Henriksveen
>> *Sent:* Friday, January 03, 2014 4:52 AM
>> *To:* Moudrick M. Dadashov; Jeremy Rowley; public at cabforum.org
>> <mailto:public at cabforum.org>
>> *Subject:* Re: [cabfpub] Definition of an SSL certificate
>>
>> Hi Moudrick
>>
>> There might not be a real use case for including a domain name in a
>> QC, but as a trusted CA we take the responsibility for the accuracy of
>> information in all certs we issue. And that was my point and why I am
>> not very concerned about the described attack scenario.
>>
>> Regards
>>
>> Mads
>>
>> *From:*public-bounces at cabforum.org
>> <mailto:public-bounces at cabforum.org>
>> [mailto:public-bounces at cabforum.org] *On Behalf Of *Moudrick M. Dadashov
>> *Sent:* 3. januar 2014 11:51
>> *To:* Mads Egil Henriksveen; Jeremy Rowley; public at cabforum.org
>> <mailto:public at cabforum.org>
>> *Subject:* Re: [cabfpub] Definition of an SSL certificate
>>
>> Mads,
>>
>> On 1/3/2014 11:49 AM, Mads Egil Henriksveen wrote:
>>
>>     The attack scenario assumes that the QC can be chained to a root
>>     cert in a trusted CA root store. This means that the CA should
>>     know the root store requirements and should be aware of the risk
>>     issuing any cert that could be used as an SSL certificate.
>>
>>     Buypass do issue both QC and SSL certificates and with the
>>     DigiNotar attack back in 2011 we realized that the browsers do
>>     accept a lot of certificates as SSL certificates. Since then we
>>     have had strict controls to ensure that no certificate is issued
>>     with an unverified domain name. I guess most of the trusted QC
>>     issuers who also issue SSL certificates are aware of this, I would
>>     not be very concerned about this attack scenario.
>>
>> What is the use case when in a QC we'd need a [any/unverified] domain
>> name? (aren't CAs responsible for the accuracy of information in the
>> QCs they issue?).
>>
>> However, I do support the idea of a technical definition of an SSL
>> certificate and I like the proposal from Ryan Hurst requiring the
>> BR/EV OIDs.
>>
>> Under ETSI framework compliance assumes two things: compliance with
>> the corresponding requirements plus certificate profile compliance.
>> These two categories exist as separate documents (under their own ETSI
>> IDs).
>> Ryan's proposal is definitely a  good step forward, I'd vote with my
>> both hands if we go even further, and like ETSI, have separate BR/EV
>> profile specifications.
>>
>> Thanks,
>> M.D.
>>
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