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Re: re: Expiring Passwords
On Thu, 8 Jan 1998 12:06:25 -0500 (EST) Rob Earhart <rob@xxxxxxxxxxxxxx>
> > (3) Encrypting the whole session is not the right option, because it
> > either can't be exported or is worthless for protecting a passphrase. If
> > you encrypt *just* the old & new passphrase then it should be exportable
> > even with real encryption.
> I find this argument specious, unless you've got a statement from the US
> government that such a scheme would be exportable (which wouldn't make any
> sense, but that hasn't exactly stopped the government before).
> I fail to see the distinction between encrypting just the passphrase,
> and encrypting the entire session, when the connection only provides the
> ability to change one's passphrase.
If you are encrypting the entire session, then you are free to pass whatever
data you would like over the connection with no way for big brother to verify
that it at least pretends to be protocol X. The entire protocol will have
variable, non-verifiable data lengths that could very easily hold relatively
large encoded messages containing the floorplan of the Pentagon.
While you could decide to use 1000 character passwords, any encrypted item of
this size in a password change protocol that exposed all but the passwords
would be suspect. In other words, it is possible to pass data rather than
legitimate passwords, it is much easier to detect that someone is doing so and
much harder to mask.
This has always been the jist of the "authentication OK, channel protection
BAD" argument used by the US Government spooks. It is reasonable -- hardly.
It is what it is though.