Subject: [therightkey] Principle of least privilege...

From: Phillip Hallam-Baker <[email-masked]>
Date: Thu, 2 Apr 2015 13:46:48 -0400

CNNIC is an opportunity to learn from mistakes.

One conclusion I draw is that PKIX and OpenPGP have very different
expectations of trust providers. We could express OpenPGP key signings
as PKIX certificates but this would be a mistake. They are better
understood to be 'endorsements' rather than 'certificates'.

Another conclusion is that there is a lot of infrastructure in the
PKIX world that should not be abandoned or ignored lightly. Mistakes
are not evidence of a flawed system unless there is no adaptation. In
the wake of DigiNotar the Web PKI has changed significantly and we are
also in the process of adding TRANS.

A possible model for future PKI is to think in terms of a victorian
skyscraper. There is a steel structure and a brick exterior. Both are
necessary for the structure to stand up.

I think we need to rethink how the principle of least privilege
applies here and make sure we are doing everything we can to minimize
risk.

As a matter of policy, no cert should ever issue for a private key
that is not under the direct control of a CA unless one of the
following apply to the corresponding cert:

1) The other party has CP, CPS and full audit for operating a CA.
2) There is a name constraint.
3) It is an end entity certificate.

Further no private key should ever be in a network accessible device
unless the following apply:

1) There is a path length constraint that limits issue to EE certs.
2) It is an end entity certificate.

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From: Nico Williams <[email-masked]>
Date: Thu, 2 Apr 2015 14:14:02 -0500

> 3) It is an end entity certificate.

EE is a kind of name constraint.

(1) is a non-starter, or would have been had we had universal deployment
of name constraints.

> 2) It is an end entity certificate.

Well, no, some CAs need to be on-line, but then they should have an
online key and an off-line key signing the online key's cert.

Nico
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