On Wed, 27 Dec 2000, Theodore Y. Ts'o wrote:
> From: Bram Cohen <[EMAIL PROTECTED]>
>
> The problem is that if someone performs MITM on you, you get a warning
> saying 'I don't know who this is warning warning warning blah blah blah,
> would you like to give up connecting or just hope it isn't really a
> problem?' Of course, most people choose to hope the problem goes away -
> I've done this several times myself, sysadmins often forget to copy ssh
> keys between machines.
>
> In the first place, it only happens the first time you contact a
> particular host.
It gets shown every time the host machine changes it's key, which has
happened several times to me, on several unrelated machines, often without
advance warning. In no cases was it actually a MITM attack.
> In the second, the message is a tad bit stronger than that.
Maybe it should mention that if you ignore that message you could wind up
having the same fate as Wil E. Coyote.
> In the third place, if you're using RSA authentication (which is
> far more convenient since you don't have to keep typing your password),
> the effects of a MITM attack are much reduced.
Hardly anyone ever does that. Whether they *should* is irrelevant, they
*don't*.
> Do note that SRP is patented technology. A claim has been made that it
> is has been freely licensed by Stanford. However, I haven't seen the
> letter myself, and it's not clear what the terms of the patent license
> are.
I think the patent either hasn't been granted or has just recently been
granted. My impression speaking to Tom Wu is that he is mainly interested
in making the technology freely available, but it's probably best he
comments on that.
> The fact that the SRP home page doesn't disclose that the fact
> that it is patented, and the author has in the past tried very hard to
> get people to use it without disclosing the patent status has always
> left a bad taste in my mouth, but your mileage and personal ethical
> standards (and some might say pet peeves, I grant that) may vary.
I'm inclined to assume he's tried to promulgate it mostly because it's
better technology.
> My personal recommendation to any such Linux distributors would be to
> get any kind of patent license agreement in signed, ink-on-paper
> first....
I think that would be an exceedingly overly cautious, one might even say
wimpy, approach, especially if all that's included is the password file
format and not the tools which use it.
> Failing that, it *really* isn't that hard to use shell scripts to rdist
> /etc/ssh/ssh_known_hosts files between all of your local machines.
Anything involving shell scripts is just plain unacceptably hard to use
for 99% of all computer users, and not worth the effort for most of the
remaining myself included.
-Bram Cohen
"Markets can remain irrational longer than you can remain solvent"
-- John Maynard Keynes
