methods for putting labels into your software?

[mlevin at jade.tufts.edu]

   I'd like to hear suggestions, or any tricks that the pros out there
know about, for putting some kind of text label or code into your
executable (compiled and linked from C code) so that if anyone were to
copy a part of the code, you could know it was a copy by somehow
seeking out that label. For example, I guess you could probably define
a static string in your C program which contained a code word, and
then you could know if a given program was copied from yours by
doing "strings a.out | grep keyword" or something.  I am looking for
ideas that are less obvious to detect - a method such that someone
copying the code wasn't likely to notice and edit out (with a patch or
something). Any ideas would be appreciated.

Mike Levin