Re: [saag] Fwd: New Version Notification for draft-belyavskiy-certificate-limitation-policy-04.txt

[Dmitry Belyavsky via dev-security-policy]

Hello,

I've just uploaded the new version of my draft.

The main difference from the previous one is more or less described syntax
of
specific limitations mentioned in text.

The answers on the question raised by Nikos are below.

=
A new version of I-D, draft-belyavskiy-certificate-limitation-policy-05.txt
has been successfully submitted by Dmitry Belyavskiy and posted to the
IETF repository.

Name:   draft-belyavskiy-certificate-limitation-policy
Revision:   05
Title:  Certificate Limitation Policy
Document date:  2017-11-25
Group:  Individual Submission
Pages:  9
URL:https://www.ietf.org/internet-drafts/draft-belyavskiy-
certificate-limitation-policy-05.txt
Status: https://datatracker.ietf.org/doc/draft-belyavskiy-
certificate-limitation-policy/
Htmlized:   https://tools.ietf.org/html/draft-belyavskiy-certificate-
limitation-policy-05
Htmlized:   https://datatracker.ietf.org/doc/html/draft-belyavskiy-
certificate-limitation-policy-05
Diff:   https://www.ietf.org/rfcdiff?url2=draft-belyavskiy-
certificate-limitation-policy-05

Abstract:
   The document provides a specification of the application-level trust
   model.  Being provided at the application level, the limitations of
   trust can be distributed separately using cryptographically protected
   format instead of hardcoding the checks into the application itself.
==

On Thu, Oct 12, 2017 at 3:03 PM, Nikos Mavrogiannopoulos via
dev-security-policy  wrote:

> On Sat, Oct 7, 2017 at 8:37 PM, Dmitry Belyavsky 
> wrote:
> > Dear Nicos,
> >
> > Sorry for the delay with my response.
> >
> > On Fri, Sep 22, 2017 at 11:06 AM, Nikos Mavrogiannopoulos <
> n...@gnutls.org>
> > wrote:
> >>
> >> On Wed, Sep 20, 2017 at 3:21 PM, Dmitry Belyavsky 
> >> wrote:
> >>
> >
> > Well, the specification I suggest should allow applying CLPs issued by
> major
> > vendors (Mozilla etc).
> > For this purposes the CLPs should be validable => signed.
>
> Hi,
>  If mozilla or any other organization is willing to deploy such PKI,
> that would be great. However for the majority of software, I'd expect
> that such files are distributed using the same channel as software,
> and thus using the same authentication mechanism for it rather than a
> new PKI. For a software distributor to use that optional signing could
> work.
>

I got your point. I'll think about allowing local CLPs to be unsigned.


>
> >> One problem with that is the fact that the existing CRL extensions are
> >> about extending attributes of the CRL, rather than adding/removing
> >> attributes to the certificate in question.
> > For this purposes I implied that the limitations are provided not by
> > extensions,
> > but as SEQUENCE of limitations related to the certificates.
> >
> > Was I wrong in the ASN1 scheme in the current version of my draft?
>
> I do not think that the presented ASN.1 description is valid.
> The "limitations  SEQUENCE," doesn't define anything in ASN.1
> (i..e, it is a sequence of what?).
>

I (hopefully) clarified the ASN.1 description in the new version.


>
> >>
> >> To bring the stapled extensions to your proposal, you'd need the
> >> Extensions and Extension fields from RFC5280, and
> >> add into limitedCertificates structure (I'll split it on the example
> >> below for clarity) the following field.
> >>
> >> LimitedCertificates  ::=   SEQUENCE OF LimitedCertificate
> >>
> >> LimitedCertificate ::= SEQUENCE {
> >> userCertificate CertificateSerialNumber,
> >> certificateIssuer   Name,
> >> limitationDate  Time,
> >> limitationPropagation   Enum,
> >> fingerprint SEQUENCE {
> >> fingerprintAlgorithm AlgorithmIdentifier,
> >> fingerprintValue OCTET STRING
> >>  } OPTIONAL,
> >> limitations  SEQUENCE,
> >>} OPTIONAL,
> >>  };
> >>
> >>
> >> stapledExtensions Extensions; <- NEW
> >> }
> >
> >
> > Sorry, I do not get the difference between the purposes of the field
> > 'limitations'
> > and 'stapledExtensions'.
>
> I cannot answer this as I cannot see the syntax of the limitations
> field. I thought it was a field intended to spark discussion rather
> than anything specific.
>

Now, when the syntax is provided, I hope it's specific enough to continue
the discussion.

-- 
SY, Dmitry Belyavsky
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Re: New Version Notification for draft-belyavskiy-certificate-limitation-policy-04.txt

[Peter Bowen via dev-security-policy]

On Tue, Sep 12, 2017 at 5:59 AM, Dmitry Belyavsky via
dev-security-policy  wrote:
> Here is the new version of the draft updated according to the discussion on
> mozilla-dev-security list.

Given that RFC 5914 already defines a TrustAnchorList and
TrustAnchorInfo object and that the Trust Anchor List object is
explicitly contemplated as being included in a signed CMS message,
would it not make more sense to start from 5914 and define new
extensions encode constraints not currently defined?

Thanks,
Peter
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Re: [saag] Fwd: New Version Notification for draft-belyavskiy-certificate-limitation-policy-04.txt

[Nikos Mavrogiannopoulos via dev-security-policy]

On Wed, Sep 20, 2017 at 3:21 PM, Dmitry Belyavsky  wrote:
> Dear Nikos
>
> On Wed, Sep 13, 2017 at 9:39 AM, Nikos Mavrogiannopoulos 
> wrote:
>>
>>
>> 4. How do you handle extensions to this format?
>>
>> Overall, why not use X.509 extensions to store such additional
>> constraints? We already (in the p11-kit trust store in Fedora/RHEL
>> systems) use the notion of stapled extensions to limit certificates
>> [0, 1] and seems quite a flexible approach. Have you considered that
>> path?
>>
>> regards,
>> Nikos
>>
>> [0].
>> https://p11-glue.freedesktop.org/doc/storing-trust-policy/storing-trust-model.html
>> [1].
>> http://nmav.gnutls.org/2016/06/restricting-scope-of-ca-certificates.html
> I've looked through the specification. It's OK for me, but I do not get
> whether the attached extensions are crypto-protected.

No, as these values are inserted by the administrator of the system,
or us (the distributor of the software), we didn't feel we needed the
introduction of additional PKI.

How do you see the infrastructure on the
draft-belyavskiy-certificate-limitation-policy? Who do you envision
signing these structures? (I assume that distribution of data will be
done by software distributors?)

>> 4. How do you handle extensions to this format?
>>
> Simillary to CRL. Do you have ideas of the extensions?

One problem with that is the fact that the existing CRL extensions are
about extending attributes of the CRL, rather than adding/removing
attributes to the certificate in question.

To bring the stapled extensions to your proposal, you'd need the
Extensions and Extension fields from RFC5280, and
add into limitedCertificates structure (I'll split it on the example
below for clarity) the following field.

LimitedCertificates  ::=   SEQUENCE OF LimitedCertificate

LimitedCertificate ::= SEQUENCE {
userCertificate CertificateSerialNumber,
certificateIssuer   Name,
limitationDate  Time,
limitationPropagation   Enum,
fingerprint SEQUENCE {
fingerprintAlgorithm AlgorithmIdentifier,
fingerprintValue OCTET STRING
 } OPTIONAL,
limitations  SEQUENCE,
   } OPTIONAL,
 };


stapledExtensions Extensions; <- NEW
}


Another difference between this profile and the p11-kit one, is that
the extensions/revocation here is done on the certificate, while in
p11-kit is done on the public key. Both approaches have pros and cons.

Another question. I also noticed the fingerprint field above. Is that
to distinguish between same CAs with different keys? In that case
using the SubjectPublicKeyIdentifier may be sufficient, and more
natural as this is how certificates with matching DNs/serials are
distinguished.

regards,
Nikos
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Re: [saag] Fwd: New Version Notification for draft-belyavskiy-certificate-limitation-policy-04.txt

[Dmitry Belyavsky via dev-security-policy]

Dear Nikos

On Wed, Sep 13, 2017 at 9:39 AM, Nikos Mavrogiannopoulos 
wrote:

>
> 4. How do you handle extensions to this format?
>
> Overall, why not use X.509 extensions to store such additional
> constraints? We already (in the p11-kit trust store in Fedora/RHEL
> systems) use the notion of stapled extensions to limit certificates
> [0, 1] and seems quite a flexible approach. Have you considered that
> path?
>
> regards,
> Nikos
>
> [0]. https://p11-glue.freedesktop.org/doc/storing-trust-policy/
> storing-trust-model.html
> [1]. http://nmav.gnutls.org/2016/06/restricting-scope-of-ca-
> certificates.html
>

I've looked through the specification. It's OK for me, but I do not get
whether the attached extensions are crypto-protected.
I'm ready to cooperate with you if there is any interest.

-- 
SY, Dmitry Belyavsky
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Re: [saag] Fwd: New Version Notification for draft-belyavskiy-certificate-limitation-policy-04.txt

[Dmitry Belyavsky via dev-security-policy]

Dear Nikos,

On Wed, Sep 13, 2017 at 9:39 AM, Nikos Mavrogiannopoulos 
wrote:

> On Tue, Sep 12, 2017 at 2:59 PM, Dmitry Belyavsky 
> wrote:
> > Hello,
> >
> > Here is the new version of the draft updated according to the discussion
> on
> > mozilla-dev-security list.
>
> Hi,
>  It seems that most of the details of the underlying format are
> missing. As far as I understand it is mostly an intentions document at
> this point right? I have few comments:
>

The format will be CRL-like.

>
> 1. requiredX509extensions: What's the reasoning behind this? If these
> extensions are required and not present why keep the root certificate
> in the trust store?
>

The main intended case is "require Certificate Transparency".
Currently using the CT is not mandatory for all CAs.


>
> 2. What is the difference between issuedNotAfter and trustNotAfter?
> The description text is unclear to me.
>

issuedNotAfter - we do not trust to the certificates issued after the date.
trustNotAfter - we do not trust certificates after the date XXX, if they
have notAfter > XXX


>
> 3. applicationNameConstraints: very useful, however it is unclear from
> the ASN.1 description how are these stored.
>

I'm not so familiar with ASN1 format. I think that syntax from RFC5280 will
fit here.

>
> 4. How do you handle extensions to this format?
>
> Simillary to CRL. Do you have ideas of the extensions?


> Overall, why not use X.509 extensions to store such additional
> constraints? We already (in the p11-kit trust store in Fedora/RHEL
> systems) use the notion of stapled extensions to limit certificates
> [0, 1] and seems quite a flexible approach. Have you considered that
> path?
>
> regards,
> Nikos
>
> [0]. https://p11-glue.freedesktop.org/doc/storing-trust-policy/
> storing-trust-model.html
> [1]. http://nmav.gnutls.org/2016/06/restricting-scope-of-ca-
> certificates.html
>

Thank you very much, I'll look at it.

-- 
SY, Dmitry Belyavsky
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