Re: Serial number verification / obfuscation (was: Re: Hiding
Re: Serial number verification / obfuscation (was: Re: Hiding
- Subject: Re: Serial number verification / obfuscation (was: Re: Hiding
- From: Andrew Merenbach <email@hidden>
- Date: Sun, 28 Jul 2002 10:46:41 -0700
The checksum could be obtained the first time the program is run, and
would be stored in preferences.
Though I suppose we run into the same old brick wall now--anybody can
edit a preferences file. So we can encode it as we write it--but then
we're back to square one again, as the proficient hacker can intercept
our encoding signals.
I guess there's no easy answer. As for my own programs, I'm just going
the old route of putting in a "guilt" window that opens every startup
until the user clicks "I Paid."
Take care,
Andrew Merenbach
On Sunday, July 28, 2002, at 09:54 AM, Charles Srstka wrote:
On Sunday, July 28, 2002, at 11:25 AM, Andrew Merenbach wrote:
On Sunday, July 28, 2002, at 04:34 AM, cocoa-dev-
email@hidden wrote:
There is actually yet another way to prevent an application from being
patched that is available in at least one big commercial application
today. Unfortunately I'm not allowed to talk about it - but it would
be
interesting if someone else could think of it and bring it to this
discussion. There's a challenge for you! :)
Hmm. The only thing that springs to mind is a checksum on the
program. Does that sound right?
One can, for example, tell the program to retrieve its own file size,
in bytes. That can be a very simple checksum, as few programs have
the same number of bytes. If a hacker/cracker patched the code, the
number of bytes might change, and then the program could render itself
unusable.
Considering that preferences are not stored within an application, and
thus that the contents of an application are only likely to change if
it is tampered with, this could be a very secure method of preventing
tampering.
Um, how would you know what the application's checksum is going to be?
When you hard-code the checksum into your app, the checksum will
change...
And if you keep the checksum in a separate file, well, that would be
extremely trivial to crack - just make a new file with the checksum of
the hacked app...
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