Gmail and SSL

Jimmy Hess mysidia at gmail.com
Mon Dec 31 01:25:04 UTC 2012


On 12/30/12, Keith Medcalf <kmedcalf at dessus.com> wrote:
> Your assertion that using "bought" certificates provides any security
> benefit whatsoever assumes facts not in evidence.

I would say those claiming certificates from a public CA provide no
assurance of authentication of server identity greater than that of a
self-signed one would have the burden of proof to show that it is no
less likely for an attempted forger to be able to obtain a false
"bought" certificate from a public trusted CA that has audited
certification practices statement,  a certificate improperly issued
contrary to their CPS,  than to have created a self-issued false
self-signed certificate.

It is certainly contrary to some basis on which web browser
implementations of HTTPS and TLS in practice rely upon.


While there have been failure in that area, regarding some particular
CAs, and some particular certificates,   the reported occurrences of
this were sufficiently rare,  that one doubts   "obtaining an
improperly issued certificate from a widely trusted CA"  is an  easy
feat for the most likely attackers to accomplish.


So  I would be very interested in any data you had to show that a CA
signature provides no additional assurance;   Especially,  when
combined with a policy of requiring manual human verification of the
certificate fingerprint,   and manual human agreement that the CA's
CPS  is strict enough for this certificate usage,  after  all the
automatic checks that it was properly signed by a well-known CA  with
an audited CPS statement,
with the usage of the certificate key  matching an allowed usage
declared by the Type/EKU/CA attributes of the subject and issuer
certs.

--
-JH



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