Re: Securing Internet mail at the MTA level

[Elliot Lee <sopwith@redhat.com>]

On Tue, 20 Aug 1996, C Matthew Curtin wrote:

> Recently, I've been looking into securing email at the MTA level, and

> Two types of approaches are possible:
>     1. Adding to the SMTP protocol itself, allowing for MTAs to
>        identify crypto-capable peers, and then performing
>        authentication and session encryption where possible.
>     2. Waiting for a cryptographic transport layer network protocol
>        (such as what is being proposed in draft-ietf-tls-ssh-00),
>        allowing SMTP to remain untouched, and only requiring MTAs to
>        add support for the new network protocol.
> 
> I like the second approach better, because it allows more problems to
> be solved with one move, and it would be easier to add crypto

> I mentioned my interest in an SSH-capable MTA to Tatu Ylonen

> My questions are:
>     1. Which of the two approaches seems to make the most sense to
>        you?

I think something like the first one would be a little bit better. In my
mind I see something similar to the "ESMTP" message appearing on
connection to the mail daemon - "SSLESMTP" if you will. Then client could
issue a "ENCD SSL" command (or whatever) and it would go crypto. I already
have used telnet and FTP clients that does something similar to this, and
they work almost transparently....

>     2. Is there another approach that could work better?
>     3. Is there interest in adding SSH functionality to sendmail in
>        the near future (either by the draft spec, or once the RFC has
>        been published)?

Have you looked at SSL? It allows different algorithms to be used, etc.
etc. (although the certificate & key distribution method uses x509, which
may be a pain...?). The SSLeay library is a freely available
implementation of SSLv2.

Just MHO,

 --==== Elliot Lee = <sopwith@redhat.com> == Red Hat Software ====--
"Usenet is like a herd of performing elephants with diarrhea; massive,
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