What email encryption is actually in use?

Bill Stewart bill.stewart at pobox.com
Wed Oct 2 03:22:07 EDT 2002

At 09:05 AM 10/01/2002 -0700, Major Variola (ret) wrote:
>So yes Alice at ABC.COM sends mail to Bob at XYZ.COM and
>the SMTP link is encrypted, so the bored upstream-ISP netops
>can't learn anything besides traffic analysis.
>But once inside XYZ.COM, many unauthorized folks could
>intercept Bob's email.  Access Control is sorely lacking folks.

I'm running Win2000 in "You're Not The Administrator" mode.
Since somebody else is root and I'm not, the fact that
my network admins could eavesdrop on my link traffic
isn't a big deal, especially when they set up my PC's software.
And if I do pretend to trust my machine against some insiders,
I can use SSH, SSL, and PGP to reduce risks from others...
Also, STARTTLS can reduce eavesdropping at Alice's ABC.COM.

If your organization is an ISP, the risks are letting them
handle your email at all (especially with currently proposed
mandatory eavesdropping laws), and STARTTLS provides a
mechanism for direct delivery that isn't as likely to be blocked
by anti-spamming restrictions on port 25.
Now to get some email *clients* using it.

On the other hand, if your recipient is at a big corporation,
they're highly likely to be using a big shared MS Exchange server,
or some standards-based equivalent, so the game's over on that end
before you even start.  Take the STARTTLS and run with it...

>Link encryption is a good idea, but rarely sufficient.

Defense in depth is important for real security.
STARTTLS can be a link-encryption solution,
but it can also be part of a layered solution,
and if you don't bother with end-to-end,
it's a really good start, and isolates your risks.
It also offers you some possibility of doing certificate management
to reduce the risk of man-in-the-middle attacks from
outside your organization, and does reduce some traffic analysis.

> >at Tuesday, October 01, 2002 3:08 AM, Peter Gutmann
> ><pgut001 at cs.auckland.ac.nz> was seen to say:
> >> For encryption, STARTTLS, which protects more mail than all other
> >> email encryption technology combined.

If your goal is to encrypt 20% of the net by Christmas,
STARTTLS will get a lot closer to that than a perfect system.
Similarly, IPSEC using the shared key "open secret"
would have been a much-faster-deployed form of opportunistic
encryption than the FreeSWAN project's more complex form
that wants some control over DNS that most users don't have.

In the absence of a real Public Key Infrastructure,
neither is totally man-in-the-middle-proof,
so if the Feds are targeting *you* it's clearly not enough,
but reducing mass-quantity fishing expeditions increases
our security and reduces the Echelon potential -
especially if 90% of the encrypted material is
routine corporate email, mailing lists, Usenet drivel, etc.

At 01:20 PM 10/1/02 +0100, David Howe wrote:
> >I would dispute that - not that it isn't used and useful, but unless you
> >are handing off directly to the "home" machine of the end user (or his
> >direct spool) odds are good that the packet will be sent unencrypted
> >somewhere along its journey. with TLS you are basically protecting a
> >single link of a transmission chain, with no control over the rest of
> >the chain.

You can protect most of the path if your firewalls don't interfere,
and more if your recipients' don't.

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