Implementing software licensing in FreeBSD

Andrew P. infofarmer at
Wed Oct 12 03:58:14 PDT 2005

On 10/12/05, Jonathon McKitrick <jcm at> 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

I don't see a single reason for this question
being asked here.

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