'How to build a dongle (hardware lock)'
Hello PICers. This is my first pic project (first project at all).
I must build a dongle (hardware lock) attached to LPT. So I have some
1. Is there any standard for fardware locks.
2. Is there design I can follow in my work.
3. How I can power the chip (CENTRONICS doesn't have +5V line)
Any ideas ? I would appreciate any advise. Thanks,
P.S. I have only mailftp access.
Greg Marchokov Mail to: bgtus4.vmei.acad.bggimar
Technical Universety - Sofia
8 Rilska street,
|> 2. Is there design I can follow in my work.
Might look into P/N Sequences.. Individual dongles implement VERY large
P/N counters (huge shift registers, where the XOR taps create a particular
P/N sequence that is 2^N where N is very large. Same idea as Psuedo-random
generators). Software sends a signal to dongle requesting validation,
dongle sends back next value in its sequence. Software (if it has correct
polynomial (e.g. the password/key) and same P/N sequence) must respond with next
element sequence. If it doesn't, I imagine dongle should freeze for 2 seconds..
position in sequence must be stored in NV memory. I don't know if this is what
real dongles do, there is a real good book out there, something like "Practical
> 3. How I can power the chip (CENTRONICS doesn't have +5V line)
>Any ideas ? I would appreciate any advise. Thanks,
Parasitically pull power from one of the data pins?.. Same trick folks
use to self-power RS232 devices from one of the RTS/CTS lines...
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 chinet.com, or schneier
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!)
let me know ! if u got anything
|>let me know ! if u got anything
A friend of mine took a look at building an Autocad dongle. The logic behind
it was (at the time) fairly simple but even a 10MHz processor worked an
order of magnitude slower than the dongle. I suppose if you had access to
gate arrays you might make one run fast enough.
I guess that with the wider availability of 'hard' cryptography the current
generation of dongles will use keys to protect their software. Something like :-
1) PC generates a random number and transmits it to dongle along with a
validation code (software serial number).
2) Dongle masks random code with decryption key for software then encrypts
the result and sends it to the pc.
3) PC decrypts and subtracts it's random code from response. Resulting code
is key to decrypt software modules.
I guess all the encryption and decryption could be carried out in a PIC
without any real problem, it should be quite cost-effective too.
Keith Dowsett "Variables won't; constants aren't."
Snail mail: MRC Clinical Sciences Centre, Cyclotron Unit.
Hammersmith Hospital. London W12 0NN.
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