Re: Protection/Time Limiting my software

From: Ben Measures (saint_abroadremove_at_removehotmail.com)
Date: 03/06/04 

Date: Sat, 06 Mar 2004 00:20:21 +0000

RoWsRaIrTiEo wrote:
> 05 Mar 2004, "Andrew Kennedy" <andrewkennedy2@LOGev1.net> wrote:
>
>>RoWsRaIrTiEo <non@esist.eeee> wrote:
>>
>>>If the distribution is with cd-rom, and if your program is 300MB?
>>>(someone would have slow Internet connection)
>>>I think that if I want to protect a program
>>>Use the demo like you say + a file.key.cpr with a key + a file.cpr
>>>cryptographed that has the whole program.
>>>
>>>Demo program write in the file.key.cpr information on his system too.
>>>
>>>If someone want that program, pay, email his key and I send
>>>new_key(file.key.cpr) [tuned for his system es: I have hear that the
>>>cpus have a unique id. number] for decrypt his file.cpr and
>>>to tune the program in the way that only one pc can run that program.
>>>(is it possible to build a program that decrypts its .data on the fly
>>> and jmp to it?) (yes for *.com)
>
>
>>That is an idea I hadn't thought of. By sending them the key upon payment,
>>I avoid having to send the whole fully functional program.
>
>
> But we have to consider the chance that someone finds the way to break
> the crypto system (Es. someone find the way of factoring numbers =>
> rsa ko)
>

You only have to crack the weakest *** in the armour. The weakness
here is the "tuning for the system".

The only way to eliminate that weakness is to encrypt each and every
"full function upgrade" with a different key.

This means they will all be unique and means that the cost of mass
producing CDs would be astronomical. Then again, if it is for a small
run of <100 copies, it might be feasible to do.

Still, a perfect copy protection method hasn't really been found (except
maybe for online services, like Sierra's Steam). 

-- 
Ben M.
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