At 01:18 AM 10/17/97 -0700, Bill Stewart wrote: At 08:40 AM 10/16/1997 +0000, Attila T. Hun wrote:
I have not seen any further discussion on my suggestion to create a sendmail type daemon which implements DH between mail clients. this, of course, is on the presumption that DH is a wrapper for an already encrypted packet,
DH between mail clients and servers is a really fine idea if you're starting from scratch, but sendmail is such a wretched hive of crime, corruption, and villainy that nobody in their right mind really wants to mess with it. You could implement it as a sendmail extension using the EHLO stuff, but you'd have to go get people to adopt it widely once you'd done it; I suppose if you could talk Netscape and Eudora into adding DH exchange to their client code and get it into a few popular servers, you'd have a large fraction of the Internet's email encrypted, which would be a Good Thing. It'd still have some major traffic analysis issues, and if you want to deal with the Man In The Middle problem, you need a key distribution infrastructure, which is much harder. An alternative approach is to encrypt everything using IPSEC, and you don't have to mess with Sendmail, but there are performance issues, and there's a lot of work getting it deployed also. There's another solution too -- make your mail servers talk with TLS (Transport Level Security, a.k.a. SSL). This solves some problems and not others. If your SMTP path includes any hops, then the message is in plaintext on that machine. Complicating it further, you cannot reliably enforce what the hops will be. This is one of the reasons that email keys are sometimes considered comm keys and sometimes storage keys. Jon ----- Jon Callas jon@pgp.com Chief Scientist 555 Twin Dolphin Drive Pretty Good Privacy, Inc. Suite 570 (415) 596-1960 Redwood Shores, CA 94065 Fingerprints: D1EC 3C51 FCB1 67F8 4345 4A04 7DF9 C2E6 F129 27A9 (DSS) 665B 797F 37D1 C240 53AC 6D87 3A60 4628 (RSA)