[Cryptography] Facebook on the state of STARTTLS

[Viktor Dukhovni]

On Tue, May 20, 2014 at 11:36:45AM -0400, Eric Mill wrote:

> > My point is not that the CA certs are expensive in this case, they
> > could well have been priced quite reasonably, rather the issue
> > is that even at $0.01 they are entirely futile for SMTP.  So whether
> > you spend $0.01 or $1,000.00 you still get nothing.
> >
> 
> Could you explain why CA certs are futile for SMTP? It's not immediately
> obvious to me. (I'm new to STARTTLS, have never configured it.)

Fortunately, I have the analysis written down:

    http://tools.ietf.org/html/draft-ietf-dane-smtp-with-dane#section-1.3
    http://tools.ietf.org/html/draft-ietf-dane-smtp-with-dane#section-1.3.1
    http://tools.ietf.org/html/draft-ietf-dane-smtp-with-dane#section-1.3.2
    http://tools.ietf.org/html/draft-ietf-dane-smtp-with-dane#section-1.3.3
    http://tools.ietf.org/html/draft-ietf-dane-smtp-with-dane#section-1.3.4

start at the top of 1.3 and read through the end of 1.3.4 (which
ends with Goedel's CA PKI theorem, any set of PKIX CAs is either
incomplete or inconsistent).

-- 
	Viktor.