[cabfpub] Ballot 108: Clarifying the scope of the baseline requirements
Jeremy Rowley
jeremy.rowley at digicert.com
Fri Aug 2 11:19:05 UTC 2013
There is a potential conflict that I think needs more data and discussion:
1) If intermediates and EE certs lacking an EKU are exempt from the BRs, a
compromise event similar to DigiNotar is probable. The BRs raise the bar
for all certs that can either create or act as an SSL certificate. Exempting
some certs for purely policy reasons creates a failure in this intended
purpose.
2) If intermediates and EE certs lacking an EKU are included within the BRs,
qualified certs will be impacted. At least two CAs will need to modify
operations and change their certificates in a way that may affect
non-browser clients and doesn't necessarily conform to non-SSL cert
profiles.
Moudrick and Rijt - To move forward, we need to know which clients are
effected and the extent of this issue. Can you issue a test qualified cert
with an EKU other than the ones listed in ballot 108 and report on which (if
any) clients will fail? This would be very useful to know and help shape
further discussion.
If no clients fail, I propose we move forward with this ballot, recognizing
that CAs issuing qualified certs will need to change their operations. I
will not opine on whether existing non-compliant certs should be revoked,
but all certs issued after the effective date of the ballot must either
include an EKU excluding them from the BRs or comply with the BRs. This may
require re-signing intermediates.
If clients fail, then we'll need to discuss how to tailor either the cert
contents or the BR scope in a manner that mitigates the risks presented by a
compromised or mis-issued cert.
Thoughts?
Jeremy
-----Original Message-----
From: Ryan Sleevi [mailto:sleevi at google.com]
Sent: Thursday, August 01, 2013 6:47 PM
To: Moudrick M. Dadashov
Cc: jeremy rowley; CABFPub
Subject: Re: [cabfpub] Ballot 108: Clarifying the scope of the baseline
requirements
Moudrick,
The importance of clarifying that the intermediates are in scope is that
such intermediates are capable of issuing any kind of certificate (including
server certificates), so it's important to consider them in scope.
The comment about permitting EKUs in intermediate certificates - and their
value - has been discussed in the context of Ballot 105. The short answer is
that several client libraries *further* restrict the acceptable EKUs based
on the transitive EKUs of the certificate chain it appears in.
That is, if a subordinate CA certificate *has* an EKU extension, and it
lacks the aforementioned EKUs, then any certificates issued by that CA will
*not* be accepted for server auth - regardless of what EKUs the leaf says.
That is, treating EKUs in intermediates as "eku constraints", for lack of a
better term.
While this may be seen as controversial to "PKIX purists", it's been
deployed for over a decade, and offers a reasonable path for scoping
subordinate CAs. Note that RFC 5280 does not *prevent* this extension from
appearing in the intermediates, so such behaviour SHOULD be acceptable to
other software that does not implement this check (eg:
non-browser users of root stores)
Hopefully that clears things up.
Cheers,
Ryan
On Thu, Aug 1, 2013 at 3:56 PM, Moudrick M. Dadashov <md at ssc.lt> wrote:
> Jeremy, my comment was about Key Usage not EKU, sorry for the confuse..
>
> If the proposed change requires EKU for non EE certificates, then
> there is one more issue:
>
> RFC 5280:
> 4.2.1.12. Extended Key Usage
>
> This extension indicates one or more purposes for which the certified
> public key may be used, in addition to or in place of the basic
> purposes indicated in the key usage extension. In general, this
> extension will appear only in end entity certificates.
>
>
> Thanks,
> M.D.
>
>
> On 8/1/2013 11:52 PM, Jeremy Rowley wrote:
>
> Thanks Moudrick.
>
>
>
> None of those documents require a certificate to include the anyEKU or
> no EKU. Is there any software that actually requires the anyEKU or no
> EKU or is this just something that has happened over time with CAs?
> If there isn't an actual reason to put this in Qualified certs (other
> than CAs have included it in the past) then there isn't a conflict,
> and we can move forward with the ballot. Issuers of qualified certs
> will just need to start inserting the correct EKUs. The problem (and
> related danger) is real enough that certs with anyEKU or no EKU should be
covered by the BRs.
>
>
>
> Jeremy
>
>
>
> From: Moudrick M. Dadashov [mailto:md at ssc.lt]
> Sent: Thursday, August 01, 2013 11:39 AM
> To: jeremy.rowley at digicert.com
> Cc: 'Ryan Hurst'; 'CABFPub'
> Subject: Re: [cabfpub] Ballot 108: Clarifying the scope of the
> baseline requirements
>
>
>
> Jeremy,
>
> 1. ETSI TS 101 862 V1.3.3 (2006-01) Qualified Certificate profile 2.
> ETSI EN 319 412-5 V1.1.1 (2013-01) Electronic Signatures and
> Infrastructures (ESI); Profiles for Trust Service Providers issuing
> certificates; Part 5: Extension for Qualified Certificate profile
>
> also have a look:
>
> ETSI TS 119 412-2 V1.1.1 (2012-04) Electronic Signatures and
> Infrastructures (ESI); Profiles for Trust Service Providers issuing
certificates; Part 2:
> Certificate Profile for certificates issued to natural persons.
>
> Search and download here:
>
> http://pda.etsi.org/pda/queryform.asp
>
> need to register, its free.
>
> Thanks.
> M.D.
>
> On 8/1/2013 7:18 PM, Jeremy Rowley wrote:
>
> Do you have a link for the profile? None of the qualified cert profile
> recommendations or requirements I am aware of require the anyEKU or
> omission of the EKU. They all say EKUS MUST be set in accordance with
5280.
>
>
>
> Jeremy
>
>
>
> From: public-bounces at cabforum.org [mailto:public-bounces at cabforum.org]
> On Behalf Of Moudrick M. Dadashov
> Sent: Thursday, August 01, 2013 9:25 AM
> To: Ryan Hurst
> Cc: 'CABFPub'
> Subject: Re: [cabfpub] Ballot 108: Clarifying the scope of the
> baseline requirements
>
>
>
> I see potential problem for ETSI Qualified SSL certificates, if key
> usage requirements remain mandatory as it is now with the Qualified
> el. signature certs.
>
> Thanks,
> M.D.
>
> On 8/1/2013 5:28 PM, Ryan Hurst wrote:
>
> There is nothing in the RFC that requires applications to treat the
> presence of the EKU as mandatory:
>
>
>
> Certificate 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.
>
>
>
> In fact the processing semantics defined in the RFC result in the
> behavior you see in all browsers today. That is if extended key usage
> is present the certificate is good for all usages, that if any key
> usage is present the certificate is only good for the specified usages.
>
>
>
> If the extension is present, then the certificate MUST only be used
>
> for one of the purposes indicated. If multiple purposes are
>
> indicated the application need not recognize all purposes
> indicated,
>
> as long as the intended purpose is present.
>
>
>
> While this behavior does require CAs to be mindful of what
> applications require to understand the implications of their
> certificate profiles it is both standards compliant and the way things
> have been since the introduction of this extension.
>
>
>
> As for key usage; most libraries (certainly CryptoAPI) don't pay
> attention to the key usage extension; that is with the exception of
keyCertSign.
> Additionally its perfectly legitimate for an application to ignore the
> Key Usage field:
>
>
>
> This extension indicates one or more purposes for which the
> certified
>
> public key may be used, in addition to or in place of the basic
>
> purposes indicated in the key usage extension.
>
>
>
> And the specification of the EKU of server authentication includes a
> set of specific KUs that are consistent with the extension:
>
> id-kp-serverAuth OBJECT IDENTIFIER ::= { id-kp 1 }
>
> -- TLS WWW server authentication
>
> -- Key usage bits that may be consistent: digitalSignature,
>
> -- keyEncipherment or keyAgreement
>
>
>
> Given these facts I do not think it makes sense to include KU as part
> of the definition of scope.
>
>
>
> Ryan
>
> From: public-bounces at cabforum.org [mailto:public-bounces at cabforum.org]
> On Behalf Of Rijt, R.A. van de (Robert) - Logius
> Sent: Thursday, August 01, 2013 5:09 PM
> To: jeremy.rowley at digicert.com; 'Steve Roylance'
> Cc: 'CABFPub'
> Subject: Re: [cabfpub] Ballot 108: Clarifying the scope of the
> baseline requirements
>
>
>
> Ideally, only certificates that explicitly contain an EKU with
> serverauth would be considered SSL certs. All other certs should be
> dismissed. That would be in line with the RFC, but I realize this
> proposal might even be more impractical.
>
>
>
> I would suggest though to add to the current definition that only
> certificates that contain a KeyUsage with the digitalsignature and
> keyEncipherment and / or keyAgreement bits set, would be considered
> SSL certificates. It just does not make sense to mandate that a
> personal certificate on a SSCD with KeyUsage non-repudation and no EKU
> would be considered an SSL certificate. That is not how I have interpreted
RFC 5280.
>
>
>
> If the proposed definition is accepted all certificates with noEKU or
> anyEKU bits set will be governed by the BR. That means that all client
> certificates with those bits set, SSL or otherwise, will be governed
> by the rules of the BR. This in turn means that a client certificate
> must contain a FQDN, which it obviously cannot. In my view, adopting
> the proposed definition would lead to a situation where no client
> certificates can be issued under the roots present in the root
> programs, unless the burden of change is placed on those CAs issuing
> client certificates, forcing them to add keyusage bits to their
> certificates that are not compulsory through the RFCs. Furthermore, in
many cases the anyEKU is relied on by software using client certificates.
>
>
>
> Regards,
>
> Robert
>
>
>
>
>
> Van: Jeremy Rowley [mailto:jeremy.rowley at digicert.com]
> Verzonden: donderdag 1 augustus 2013 14:06
> Aan: 'Steve Roylance'; Rijt, R.A. van de (Robert) - Logius
> CC: 'CABFPub'
> Onderwerp: RE: [cabfpub] Ballot 108: Clarifying the scope of the
> baseline requirements
>
>
>
> That is likely the way forward. Mozilla can enable roots for "Web,
> code, or client" . I assume the other browsers probably have a similar
designation.
> If the root is disabled for "web" then the cert could not perform SSL
> and would not be considered enabled in the browser's trust store (for
SSL/TLS).
> The tweak to the proposed language would be nominal.
>
>
>
> From: public-bounces at cabforum.org [mailto:public-bounces at cabforum.org]
> On Behalf Of Steve Roylance
> Sent: Thursday, August 01, 2013 5:25 AM
> To: Rijt, R.A. van de (Robert) - Logius
> Cc: CABFPub
> Subject: Re: [cabfpub] Ballot 108: Clarifying the scope of the
> baseline requirements
>
>
>
> Hi Robert.
>
>
>
> Root program's have the ability to mark specific roots for specific
> uses therefore you can still offer public trust but for a specific
> need. Maybe that's a way forward? As with Name Constraints it makes
> roots (or Subordinate CAs) less attractive as targets as their value
> to an attacker is decreased.
>
>
>
> Regards Steve
>
>
> Sent from my iPhone
>
>
> On 1 Aug 2013, at 12:04, "Rijt, R.A. van de (Robert) - Logius"
> <robert.vande.rijt at logius.nl> wrote:
>
> For qualified certificates under ETSI that need to be publicly
> trusted, a private root would not be an option. Moreover, developing a
> private, not-publicly trusted root and rolling out end-entity
> certificates takes time. I am talking about a year at least.
>
>
>
> I wonder if everyone else is realizing the impact on "non-SSL"
certificates.
> Especially the CA's not participating in the CABforum because they do
> not issue SSL certs (or thought they did not), but do have a publicly
> trusted root.
>
>
>
> Robert
>
>
>
> Van: Jeremy Rowley [mailto:jeremy.rowley at digicert.com]
> Verzonden: donderdag 1 augustus 2013 12:56
> Aan: Rijt, R.A. van de (Robert) - Logius; 'Ryan Hurst'
> CC: 'CABFPub'
> Onderwerp: RE: [cabfpub] Ballot 108: Clarifying the scope of the
> baseline requirements
>
>
>
> Which is why you will now have to issue these off a root not trusted
> by a participating browser. The safetynet is the problem since makes
> them an SSL cert. I don't think you can both have a safetynet like
> this and issue the cert from a trusted root.
>
>
>
> Jeremy
>
>
>
> From: Rijt, R.A. van de (Robert) - Logius
> [mailto:robert.vande.rijt at logius.nl]
> Sent: Thursday, August 01, 2013 4:53 AM
> To: Ryan Hurst; jeremy.rowley at digicert.com
> Cc: CABFPub
> Subject: RE: [cabfpub] Ballot 108: Clarifying the scope of the
> baseline requirements
>
>
>
>
>
> Thanks for your reply, Jeremy. I conclude that with this new definition:
>
>
>
> 1. We are forcing everyone with public certificates to use the EKU;
>
> 2. We are forcing everyone with public certificates not to use the
> anyExtendedKeyUsage unless it is a SSL certificate;
>
> 3. thereby forcing everyone to spell out all the applicable EKUs
one-by-one.
> My experience is that a lot of software cannot handle this, so the
> certificate cannot be used for the function intended. That is why the
> anyExtendedKeyUsage is often used as a safetynet.
>
>
>
> Robert
>
>
>
>
>
> Van: Ryan Hurst [mailto:ryan.hurst at globalsign.com]
> Verzonden: donderdag 1 augustus 2013 12:45
> Aan: jeremy.rowley at digicert.com
> CC: Rijt, R.A. van de (Robert) - Logius; CABFPub
> Onderwerp: Re: [cabfpub] Ballot 108: Clarifying the scope of the
> baseline requirements
>
>
>
> I concur with Jeremy's analysis.
>
> Ryan Hurst
>
> Chief Technology Officer
>
> GMO Globalsign
>
>
>
> twitter: @rmhrisk
>
> email: ryan.hurst at globalsign.com
>
> phone: 206-650-7926
>
>
>
> Sent from my phone, please forgive the brevity.
>
>
> On Aug 1, 2013, at 1:12 PM, "Jeremy Rowley"
> <jeremy.rowley at digicert.com>
> wrote:
>
> HI Rijt,
>
>
>
> I think the certificates you mentioned will (and should) qualify under
> the BRs if are issued from a root that is included in one of the
> adopting browser's trust stores.
>
>
>
> Here's my logic:
>
> 1) Certs that don't have an EKU or that include the anyEKU can be
used
> as SSL certs, regardless of their intended purposes and should
> (arguably) be under the BRs.
>
> 2) However, as you mentioned, many certificates assert the anyEKU,
have
> noEKU, or even contain the server authentication EKU that are never
> intended to be used on a server.
>
> 3) I believe the certificates referenced typically lack an FQDN.
> Including these certificates under the BR umbrella is problematic
> because the certificates can't function in the intended manner and
> comply with the BRs. The CN is an identifier for the equipment, which
> violates Section
> 9.2.2 of the BRs.
>
> 4) Requiring an FQDN for inclusion in the BRs is not a way forward
> since that would make the sections on internal server names out of
> scope of the BRs. In fact, the identifier in these certificates is
> indistinguishable from and qualifies as an internal name, meaning the
certificate presents all
> of the concerns previously expressed by PayPal. Continuing to trust
these
> certificates would be the same as not deprecating internal server name
> certificates
>
> 5) Therefore, these certificates must either be included in the BRs,
> and include an FQDN, or need to be issued off of a non-publicly
> trusted root certificate.
>
>
>
> The position you expressed is why I wanted to raise the issue and why
> I think we need to resolve what the BRs actually cover.
>
>
>
> Jeremy
>
>
>
> From: public-bounces at cabforum.org [mailto:public-bounces at cabforum.org]
> On Behalf Of Rijt, R.A. van de (Robert) - Logius
> Sent: Thursday, August 01, 2013 3:05 AM
> To: 'CABFPub'
> Subject: Re: [cabfpub] Ballot 108: Clarifying the scope of the
> baseline requirements
>
>
>
> Although I understand the need for tightening the definition and I can
> follow the reasoning below to a certain point I feel that, instead of
> tightening it, the new definition seems to have broadened the scope.
> The vast majority of certificates issued under the Logius PKIoverheid
> root are not intended for the identification of SSL servers. However,
> roughly 90% of these certificates will now fall under this new
> definition. In the present version, the scope made clear that the BR
> only addressed certificates meant for servers.
>
>
>
> What about personal certificates on a SSCD that have no EKU or have an
> anyExtendedKeyUsage as a safetynet? Would these certificates suddenly
> by seen as SSL certificates although they are obviously not intended
> for servers? What about certificates issued to autonomous devices such
> as onboard computers in taxicabs or domestic gas meters, to name but
> two? Would these be considered SSL certificates if they have no EKU or
> the clientauth EKU in combination with anyExtendedKeyUsage?
>
>
>
> Regards,
>
> Robert
>
>
>
>
>
>
>
>
>
> Van: public-bounces at cabforum.org [mailto:public-bounces at cabforum.org]
> Namens Ryan Sleevi
> Verzonden: maandag 29 juli 2013 22:57
> Aan: Kelvin Yiu
> CC: CABFPub
> Onderwerp: Re: [cabfpub] Ballot 108: Clarifying the scope of the
> baseline requirements
>
>
>
> They're still respected (for better or worse) by Apple, NSS, and Android.
>
> Even if that changed tomorrow, the fact that a significant portion of
> the deployed user base for those products may not upgrade immediately
> suggests it would be wise to keep them in scope - especially given
> that even few products implement Microsoft's EKU chaining behaviour for
intermediates.
>
> On Jul 29, 2013 1:52 PM, "Kelvin Yiu" <kelviny at exchange.microsoft.com>
> wrote:
>
> I prefer to drop any mention of the MS or Netscape SGC OIDs. These
> OIDs have been obsolete for over a decade and have ceased to have any
> meaning on MS platforms since Windows 2000.
>
> Kelvin
>
> -----Original Message-----
> From: public-bounces at cabforum.org [mailto:public-bounces at cabforum.org]
> On Behalf Of Ryan Sleevi
> Sent: Friday, July 26, 2013 12:35 PM
> To: jeremy rowley
> Cc: CABFPub
> Subject: Re: [cabfpub] Ballot 108: Clarifying the scope of the
> baseline requirements
>
> Jeremy,
>
> If I might suggest a slight modification to the wording, which still
> leaves things a little ambiguous. "All root and intermediate
> certificates included in a browser's trust store" - AIUI, none of the
> browsers are really accepting intermediates to the trust store at this
point.
>
> This was a sticky point when working on Mozilla's wording on this policy
to.
> Luckily, the terminology for "Root CA" and "Subordinate CA"
> may be sufficient here to help clarify.
>
> "All root certificates included in a browser's trust store, all
> subordinate CA certificates signed by one of these root certificates,
> and all end-entity certificates that either lack any Extended Key
> Usage extension or contain an Extended Key Usage extension that contains
one of the following:
> - Server Authentication (1.3.6.1.5.5.7.3.1)
> - anyExtendedKeyUsage (2.5.29.37.0)
> - Netscape Server Gated Cryptography (2.16.840.1.113730.4.1)
> - Microsoft Server Gated Cryptography (1.3.6.1.4.1.311.10.3.3) are
> expressly covered by these requirements."
>
> Note that Appendix B, 3.F lists other values as SHOULD NOT. However,
> that presumably only applies when a certificate is 'in scope' of the
> BRs, hence the restatement of potential EKUs that are relevant.
>
>
>
> On Fri, Jul 26, 2013 at 12:22 PM, Jeremy Rowley
> <jeremy.rowley at digicert.com>
> wrote:
>> Hi everyone,
>>
>>
>>
>> As mentioned on the phone call last week, CAs have claimed exemption
>> from the BRs because the definition of a publicly-trusted SSL
>> certificate is not
>> clear. I would like to clarify the scope of the BRs to avoid confusion
>> on
>> what particular certificate contents are necessary to require
>> compliance. I am looking for on endorser (Stephen Davidson has
>> already endorsed).
>>
>>
>>
>> The third paragraph of Section 1 of the baseline requirements is:
>>
>> "This version of the Requirements only addresses Certificates
>> intended to be used for authenticating servers accessible through
>> the Internet. Similar requirements for code signing, S/MIME,
>> time-stamping, VoIP, IM, Web services, etc. may be covered in future
>> versions."
>>
>>
>>
>> I'd like to replace the above text with the following:
>>
>> "This version of the Baseline Requirements addresses all root,
>> intermediate, and end entity certificates that can be used in
>> publicly-trusted SSL handshakes. All root and intermediate
>> certificates included in a browser's trust store and all end entity
>> certificates containing an extended key usage extension of Server
>> Authentication (1.3.6.1.5.5.7.3.1) are expressly covered by these
>> requirements. Similar requirements for code signing, S/MIME,
>> time-stamping, VoIP, IM, Web services, etc. may be covered in future
>> versions."
>>
>>
>>
>> I look forward to your comments.
>>
>>
>>
>> Jeremy
>>
>>
>> _______________________________________________
>> Public mailing list
>> Public at cabforum.org
>> https://cabforum.org/mailman/listinfo/public
>>
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