Subject: [Trans] draft-ietf-trans-rfc6962-bis-28: "no security implications"

From: Andrew Ayer <[email-masked]>
Date: Tue, 20 Mar 2018 15:12:49 -0700

draft-ietf-trans-rfc6962-bis-28 added the following text to
section 4.2:

"While there are no security implications to a log accepting
a submission that does not chain to one of its accepted trust
anchors..."

This isn't true.  The certificate chain enables the logged certificate
to be attributed to a known trust anchor.  This is security-sensitive,
as without the chain, monitors and trust store operators can't respond
to a misissued certificate because they don't know which trust anchor
should be sanctioned/distrusted for misissuing the certificate.[1]

Therefore, this text should be removed.

It might also be a good idea, to avoid any future confusion about this
requirement, to add "to ensure that logged certificates are attributable
to a known trust anchor" to the sentence at the beginning of 4.2 that
explains why the requirement exists.

Regards,
Andrew

[1] In the general case, a monitor could probably construct the chain
using its own store of intermediate certificates.  But this fails if
the intermediate isn't known, which might happen in the adversarial
case where an intermediate certificate is issued for the sole purpose
of evading responsibility for a misissued certificate.