Subject: [Anima] CRLs in iDevID manufacturer signing certs?

From: Eliot Lear <[email-masked]>
Date: Thu, 9 Mar 2017 15:31:09 +0100

Hi,

What is the thinking on including CRL pointer in the manufacturer
signing cert?  This question came up in industry discussions.

Eliot

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From: Kent Watsen <[email-masked]>
Date: Thu, 9 Mar 2017 18:25:17 +0000

Hi Elliot,

> signing cert?  This question came up in industry discussions.

802.1AR says that the IDevID secrets must be stored confidentially and be not available outside the module.  In practice, a crypto processor with tamper-resistant NVRAM is used (e.g., TPM).  As such, the likelihood of the credentials being stolen/discovered are near zero, but it is not zero, as a determined adversary with sufficient resources can still have their way with it.  Still, vendors will likely conclude that protecting against that level of attack isn't necessary.  That said, vendors face a more likely scenario, of issues occurring by contract manufacturers, whether it be accidental or intentional.  And as unlikely this scenario may seem, things happen and the vendor would be without recourse if unable to issue revocations.  To this extent, setting up the infrastructure to support revocations can be compared to insurance - hopefully you never need it, but when you do, you're glad you have it.

Kent

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From: Eliot Lear <[email-masked]>
Date: Thu, 9 Mar 2017 19:29:00 +0100

Thanks, Kent.  Then it seems to me that we have a MAY floating around
for CRL checking on the part of the registrar for BRSKI.  Right?

Eliot

On 3/9/17 7:25 PM, Kent Watsen wrote:
> _______________________________________________
> Anima mailing list
> [email-masked]
> https://www.ietf.org/mailman/listinfo/anima
>

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From: Kent Watsen <[email-masked]>
Date: Thu, 9 Mar 2017 19:16:45 +0000

My view is that, if the IDevID has a CRL/OCSP URL listed, then the
validator SHOULD do the checking.  If the vendor didn't actually
want revocation checking done, then the vendor should've excluded
such information from their IDevID certs.

FWIW, 802.1AR takes a much neutral stance in Section 6.5.3 (Validation of DevIDs):

  The DevID is an X.509 credential and can be validated using the
  RFC 5280 defined mechanisms. IDevIDs are intended to have very
  long validity periods even exceeding what would normally be
  cryptographically acceptable. The manufacturer is not required
  to provide a Certificate Revocation List (CRL) although the
  validator may do CRL checking if the manufacturer provides CRLs.
  The validator may verify CRLs for LDevIDs as necessary.

Kent

-----ORIGINAL MESSAGE-----

Eliot

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From: "Beck, Stefan" <[email-masked]>
Date: Fri, 10 Mar 2017 16:47:29 +0000

Kent Watsen wrote:
> validator SHOULD do the checking.
> If the vendor didn't actually want revocation checking done, then the
> vendor should've excluded such information from their IDevID certs.
I agree, it should say SHOULD.

> the likelihood of the credentials being stolen/discovered are near zero,
> but it is not zero, as a determined adversary with sufficient resources
> can still have their way with it.
Also, if some general or implementation vulnerabilities are discovered in
the used crypto processors/ Tamper-resistant NVRAM, the likelihood may
become significantly higher than "near zero".

> vendors face a more likely scenario, of issues occurring by contract
> manufacturers, whether it be accidental or intentional.
I agree. As there may be more & diverse such scenarios one can also
think of mapping those issues to well-defined revocation reasons
(keyCompromise, cACompromise, affiliationChanged, superseded,
cessationOfOperation, certificateHold, privilegeWithdrawn, and
aACompromise).
This would allow for more detailed decisions during enrollment
(or re-enrollment after factory reset) in the local domain.

Stevie

-----Original Message-----
From: Anima [mailto:[email-masked]] On Behalf Of Kent Watsen
Sent: Thursday, March 09, 2017 8:17 PM
To: Eliot Lear <[email-masked]>; Anima WG <[email-masked]>
Subject: Re: [Anima] CRLs in iDevID manufacturer signing certs?

My view is that, if the IDevID has a CRL/OCSP URL listed, then the validator
SHOULD do the checking.  If the vendor didn't actually want revocation
checking done, then the vendor should've excluded such information from
their IDevID certs.

FWIW, 802.1AR takes a much neutral stance in Section 6.5.3 (Validation of
DevIDs):

Kent

-----ORIGINAL MESSAGE-----

Thanks, Kent.  Then it seems to me that we have a MAY floating around for
CRL checking on the part of the registrar for BRSKI.  Right?

Eliot

On 3/9/17 7:25 PM, Kent Watsen wrote:
> 802.1AR says that the IDevID secrets must be stored confidentially and be
not available outside the module.  In practice, a crypto processor with
tamper-resistant NVRAM is used (e.g., TPM).  As such, the likelihood of the
credentials being stolen/discovered are near zero, but it is not zero, as a
determined adversary with sufficient resources can still have their way with
it.  Still, vendors will likely conclude that protecting against that level
of attack isn't necessary.  That said, vendors face a more likely scenario,
of issues occurring by contract manufacturers, whether it be accidental or
intentional.  And as unlikely this scenario may seem, things happen and the
vendor would be without recourse if unable to issue revocations.  To this
extent, setting up the infrastructure to support revocations can be compared
to insurance - hopefully you never need it, but when you do, you're glad you
have it.

---

From: Michael Richardson <[email-masked]>
Date: Sat, 11 Mar 2017 15:58:54 -0500

Kent Watsen <[email-masked]> wrote:
    > 802.1AR says that the IDevID secrets must be stored confidentially and
    > be not available outside the module.  In practice, a crypto processor
    > with tamper-resistant NVRAM is used (e.g., TPM).  As such, the
    > likelihood of the credentials being stolen/discovered are near zero,

While 802.1AR would like this, I think that the BRSKI mechanism we are
describing (and re-interpreting for constrained environments in 6tisch) are
very unlikely to have serious tamper-resistant mechanisms for the IDevID
that are seperate from the system in general.

Revoking the IDevID would be useful, but it might be that the MASA can
effect the same thing by refusing to issue an ownership voucher.
This only works if ownership vouchers are to be issued online, or
they can be revoked.   This doesn't solve the same problem, but it may have
the same result.

I am also concerned about how many bytes a CRL pointer requires.  I'm
guessing it's on the order of 50 bytes for the URL and container.

--
Michael Richardson <[email-masked]>, Sandelman Software Works
 -= IPv6 IoT consulting =-