ietf-openpgp
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Re: Applicability of signed messages as proof of sending

2005-08-12 09:23:11

On Fri, 2005-08-12 at 10:39 +0100, Ian G wrote:
Len Sassaman wrote:
On Thu, 11 Aug 2005, Ian G wrote:
 
Right. I'm one of those people. This does, however, leave one open to MITM
attacks -- which are probably not that large of a threat in the general
case, but when dealing with centralized, proprietary IM systems, could
very well be a realistic problem. (This is why Trillian's SecureIM
solution fails my sniff test.)

Right.  That's an interesting point.  So GAIM
uses AIM which is a proprietary IM system.  Now,
if that was all it was, *and* one assumed that
MITM in AIM was a real threat, then this would
be plausible logically, but still weak in terms
of validation.

Gaim (please not GAIM) supports a variety of protocols besides AIM, so
that does change the threat model a bit. It'd be significantly easier to
do a MITM attack on more documented and decentralized protocols.

I'll admit that MITM attacks are rare and sophisticated, but if you're
not guarding against them, the only take you prevent is casual snooping
on the wire. If you're only going to worry about casual snooping, you
could just as well use rot13 as your "encryption". (Granted, I'm
exaggerating a little, but why bother with something as complex and
secure as OpenPGP to prevent casual snooping.) Your points about
keyloggers, etc. are very valid.

Richard Laager