On Wed, 8 May 1996, Thomas Coonan wrote:
[...]
> I don't know if this is what real dongles do, there is a real
> good book out there, something like "Practical Encryption..."...

Maybe you mean, _Applied Cryptography_ by Bruce Schneier.
I've got the first edition (ISBN 0-471-59756-2),
but I've heard that there is a more recent edition.

You can contact Bruce at schneier@chinet.com, or
voice: +1 708 524 9461, or FAX: +1 708 524 8070.

(I have no personal affiliation with Bruce, nor
 with Counterpane Systems, other than having
 contributed slightly to debugging his book...
 and debugging the book's errata list!)

Rick Miller