Re: IETF mail server and SSLv3

[Phillip Hallam-Baker <[e-mail]>]

On Thu, Mar 3, 2016 at 6:03 AM, Stephen Farrell
<[e-mail]> wrote:
>
>
> On 03/03/16 07:11, Viktor Dukhovni wrote:
>
>> The way I see it for opportunistic TLS in general, and Postfix specifically,
>> is that the sensible approach is to prune the deadwood once it is no longer
>> useful for interoperability except with a theoretical, but in practice negligible
>> to non-existent minority of peers.  That is, once removing obsolete
>> and week crypto has no practical negative consequences, we should just do it.
>
> This was something we debated during the processing of
> RFC7435. I do think the OS approach is a fine thing, but
> I'd be much more for ditching weak crypto than you.
>
> DROWN, LOGJAM and other attacks demonstrate that keeping
> weak crypto code around does have negative consequences,
> and with DROWN those are pretty impressively negative.

This is also an argument for multi-layer security.

Transport Layer Security isn't a panacea, it has limitations. Back in
1995 we had to choose the one place we applied encryption because
machines were slow. Today we can and should have multi-level security.

We need message layer security in addition to transport. And we need
an infrastructure for deploying client side key material.