On Wed, Dec 05, 2007 at 09:09:41AM -0800, John H. Robinson, IV wrote:
Todd Walton wrote:
Anybody know anything about two factor authentication?
What if I gave a token to the neighbor kid and told him to take it to
my Aunt Millie across town. An hour later Aunt Millie calls me on our
ultra-secure encrypted point to point telephone line to say that she
has it. So I open my control panel and synchronize the server with
her token, and then set her a PIN.
Was having the token out of my control for that hour a security consideration?
Depends. Let's assume that there was no *physical* attack on the fob.
Instead, the kid merely wrote down all the numbers on the fob during
that hour.
It could be possible to reconstruct the state of the PRNG inside the fob.
I don't think that it is very likely, so if you trust the courier to
neither lose it nor break into it, you should be fine.
The fob manufacturers give both physical protection, and difficulty of
recovering the PRNG state as the selling point, so it probably wouldn't be
high on the list of possibilities.
I think a rubber-hose attack is much more likely here.
Also, as long as you can authenticate Aunt Millie by voice, security of the
phone line isn't nearly as important. A more likely attack is that she is
calling in under duress to synchronize so she can connect on behalf of her
captor.
Dave
--
[email protected]
http://www.kernel-panic.org/cgi-bin/mailman/listinfo/kplug-list
