On 2020-10-30 16:29, Rob Stradling wrote:
Perhaps add: "And also include any other certificates sharing the same
private/public key pairs as certificates already included in the
requirements." (this covers the situation you mentioned where a
self-signed certificate shares the key pair of a certificate that chains
to an included root).
Jakob,
I agree that that would cover that situation, but your proposed language goes
way, way too far.
Any private CA could cross-certify a publicly-trusted root CA. How would the
publicly-trusted CA Operator discover such a cross-certificate? Why would such
a cross-certificate be of interest to Mozilla anyway? Would it really be fair
for non-disclosure of such a cross-certificate to be considered a policy
violation?
How would my wording include that converse situation (a CA not subject
to the Mozilla policy using their own private key to cross sign a CA
subject to the Mozilla policy)?
I do notice though that my wording accidentally included the case where
the private key of an end-entity cert is used in as the key of a private
CA, because I wrote "as certificates" instead of "as CA certificates".
________________________________
From: Jakob Bohm via dev-security-policy <dev-security-policy@lists.mozilla.org>
Sent: 29 October 2020 14:57
To: mozilla-dev-security-pol...@lists.mozilla.org
<mozilla-dev-security-pol...@lists.mozilla.org>
Subject: Re: Policy 2.7.1: MRSP Issue #186: Requirement to Disclose Self-signed
Certificates
On 2020-10-29 01:25, Ben Wilson wrote:
Issue #186 in Github <https://github.com/mozilla/pkipolicy/issues/186&data=04>
deals with the disclosure of CA certificates that directly or transitively
chain up to an already-trusted, Mozilla-included root. A common scenario
for the situation discussed in Issue #186 is when a CA creates a second (or
third or fourth) root certificate with the same key pair as the root that
is already in the Mozilla Root Store. This problem exists at the
intermediate-CA-certificate level, too, where a self-signed
intermediate/subordinate CA certificate is created and not reported.
Public disclosure of such certificates is already required by section 5.3
of the MRSP, which reads, "All certificates that are capable of being used
to issue new certificates, and which directly or transitively chain to a
certificate included in Mozilla’s CA Certificate Program, MUST be operated
in accordance with this policy and MUST either be technically constrained
or be publicly disclosed and audited."
There have been several instances where a CA operator has not disclosed a
CA certificate under the erroneous belief that because it is self-signed it
cannot be trusted in a certificate chain beneath the already-trusted,
Mozilla-included CA. This erroneous assumption is further discussed in Issue
#186 <https://github.com/mozilla/pkipolicy/issues/186&data=04 >.
The third paragraph of MRSP section 5.3 currently reads, " These
requirements include all cross-certificates which chain to a certificate
that is included in Mozilla’s CA Certificate Program."
I recommend that we change that paragraph to read as follows:
"These requirements include all cross-certificates *and self-signed
certificates (e.g. "Issuer" DN is equivalent to "Subject" DN and public key
is signed by the private key) that* chain to a CA certificate that is
included in Mozilla’s CA Certificate Program*, and CAs must disclose such
CA certificates in the CCADB*.
I welcome your recommendations on how we can make this language even more
clear.
Perhaps add: "And also include any other certificates sharing the same
private/public key pairs as certificates already included in the
requirements." (this covers the situation you mentioned where a
self-signed certificate shares the key pair of a certificate that chains
to an included root).
Enjoy
Jakob
--
Jakob Bohm, CIO, Partner, WiseMo A/S. https://www.wisemo.com
Transformervej 29, 2860 Søborg, Denmark. Direct +45 31 13 16 10
This public discussion message is non-binding and may contain errors.
WiseMo - Remote Service Management for PCs, Phones and Embedded
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