Re: [Uta] Review of draft-ietf-uta-email-deep-08

[Keith Moore <[e-mail]>]

On 07/25/2017 02:56 AM, Alexey Melnikov wrote:
>> Use of pinned certs isn't forbidden by the draft, but pinned certs don't
>> meet minimum confidentiality requirements.
>>
>> I think it might be possible to adequately address the security concerns
>> associated with the usual implementation of pinned certificates, but
>> working though the details seems beyond the scope of this document.
> Ok, how about inserting "typically" before "lacks a mechanism to revoke
> ...". This way you are making an observation about state of UIs without
> sounding like it is a fact of nature.
I'm thinking more along the lines of "there is currently no protocol 
defined for revocation of a pinned certificate".

TOFU isn't entirely good or evil, though it does provide a vulnerability 
that will certainly be exploited.  (We're creating a similar 
vulnerability by encouraging use of unsigned SRV records to dictate 
account configuration parameters, which seems hard to fix at the moment 
given how hard it is to deploy DNSSEC.   Maybe DNS-over-TLS will emerge 
as a way to double-check the validity of those SRV records.)

Keith