[Full-disclosure] (no subject)

["John Smith" <jsmith1001@xxxxxxxx>]

>Firstly, the user ID isn't used anywhere, although its captured.

  The KPID is used to determine the unique algorithm used for time-delay,
and the static control algorithm used to create the dynamic encryption
for the unit's auth sequence, (the two hashes created using date/time
sequence and dynamic algorithm based off of control algorithm).  I might
not have explained that very well - sorry. One consideration would be the
large amount of different algorithms to keep track of, and whether a
dynamically generated algorithm can be trusted to have invariably similar
characteristics, (ie strength, any collisions).

>Second, this is still subject to a mitm attack.

 Well, I know that the MITM attack would still be possible with the
authenticated session, as the host is compromised, but I thought the
question was how to keep the authentication itself private, as using a
compromised system means everything is available anyway. Perhaps a kind
of keep-alive using the time-delay could help prevent excessively easy
interception of the session...

>Thirdly, any message or session data is not protected as coming from the
same site to/from user, compromised workstation or keypad. Indeed, a
compromised machine may simply 'route' an attacker's data to appear to
originate from the machine that commenced the session.

Now, the session could definitely be stolen, but again, I thought we were
assuming any session was going to be compromised already. Maybe I missed
the point. If we have to protect more then the authentication scheme,
from what little I know, there would have to be NO involvement with the
compromised machine, or users who can decrypt things themselves..hehehe -
decoder ring to check your email... :) Even hardware interrupts could be
intercepted and analysed, I believe though I'm not positive, if you,
say, decided to setup a method of direct communication between the USB
peripheral and the user-interfaces, (which would be cool, anyway).

Well, that was my thought. I'm no engineer, so it was more of a stab in
the dark, but thanks for your reply :) I think the time-delay thing and
the control algorithm dynamically generating unique algorithms during
encryption could really be expanded on. I haven't seen much along those
lines, personally. Perhaps its because of the overhead.

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