[A83] Re: Making Commercial apps using the freeware key

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[A83] Re: Making Commercial apps using the freeware key


> The unfortunate thing is that commercial apps can be resigned with the
> freeware key. Oops.

Ehmm, the apps I described would be signed with the freeware key.

You enter your calc ID on som online site,
probably afer some payment agreement.

Then the server-side program would encrypt the calculator id and put it at the 
end of the unsigned application (HEX format).

The server-side program would then sign the application with the freeware key,
and send the signed app to the requester, who then has a custom application 
with his own calculator id embedded inside.

If he runs it, some code inside the app, decrypts the embedded calc id,
and compares it to the actual calc id, after which it decides to continue,
or not. (actually, it could do much different things if the id doesn't match,
think of memory or archive resets :-)

If one would remove the signing from the app, resulting in the pure hex code,
the calculator ID would still be inside, and since it is encrypted,
he would have a very hard time changing it, so it's not a simple re-signing
to check the calc id. (Disassembling isn't very productive, if you code it sneaky, [i suspect])

(same process could be used in normal programs)

Only problem is, how do you retrieve the calc ID of the calc that's
currently running it. (It shouldn't be too hard to retrieve, if I remember 
correctly, there is even a romcall for).







> 
> -----Original Message-----
> From: assembly-83-bounce@lists.ticalc.org
> [mailto:assembly-83-bounce@lists.ticalc.org]On Behalf Of Hyperbyte
> Sent: Tuesday, June 26, 2001 10:38 AM
> To: assembly-83@lists.ticalc.org
> Subject: [A83] Making Commercial apps using the freeware key
> 
> 
> 
> I just got the following idea about making commercial apps with the
> free key. (It's just hypothetical)
> 
> If you could check the calculator ID from within a program,
> (1st assumption)
> 
> then you could make some online program add the calculator ID to the end of
> the program, sign the program, and give it away.
> 
> in the app, you could then compare the (possibly encrypted) calculator ID at
> the end of the program to the calculator id of the running calc.
> 
> --Peter Martijn
> 
> 
>
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