Re: Implementing software licensing in FreeBSD

2005-10-12 Thread Andrew P. 
On 10/12/05, Jonathon McKitrick [EMAIL PROTECTED] wrote:

 Setting aside opinions on copy protection and licensing, suppose I wanted to
 implement such a scheme.

 The key itself might be a network license, or an encrypted file containing
 license info and system-specific info.  But the real issue is how to protect
 the code that accesses the key.  I know that 'wrappers' don't have much of an
 application in Unix, and are actually impractical.  But what techniques could
 be implemented within a library or archive that would make it difficult for
 someone to trace the algorithm and/or make changes to the code to remove the
 protection checks?

 jm
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No matter what the platform is, one of the most
effective tricks is to check different checksums
(CRC, MD5, SHA256...) of different parts of
different binaries at different (random) points by
inline functions. Failure to verify a binary
integrity should lead to immediate program
termination.

I don't see a single reason for this question
being asked here.
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Re: Implementing software licensing in FreeBSD

2005-10-12 Thread Kirk Strauser 
On Wednesday 12 October 2005 05:42 am, Jonathon McKitrick wrote:

 But what techniques could be implemented within a library or archive that
 would make it difficult for someone to trace the algorithm and/or make
 changes to the code to remove the protection checks?  

There is none.  The closest possibility is obfuscating the code that verifies 
the license keys and calling that code pervasively throughout your program.  
Of course, this will make your program much more complex, fragile, and 
resource-intensive, and some guy who's been cracking protected software for 
20 years will snip out your patch and release a faster, more robust version 
of your program.

Forget the licensing issues.  Copy protection will never do as it's intended.  
Please, seriously, dig back into its history of failure and see why nothing 
good can come of this.
-- 
Kirk Strauser


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