recognizing the essence

[cort]

Eric and Co. were discussing the "hiding" (obfuscating?) of source code.
I am interested in identifying source code (similarities).

I would like to review literature and available programs for recognizing
plagiarism (of computer source code).  (There is potential for a law
suit in this case.)

I have heard of computer science professors using such programs to 
thwart would-be cheaters on class programming assignments.  From what
I remember these were probabilistic.  n% likeness give m% probability
of cheating, etc.

Does anyone have pointers for me?

Cort.