@TECHREPORT{CollbergThomborsonLow97a,
   AUTHOR    = "Christian Collberg and Clark Thomborson and Douglas Low",
   TITLE     = "A Taxonomy of Obfuscating Transformations",
   MONTH     = jul,
   YEAR      = 1997,
   NUMBER    = 148,
   NOTE      = "http://www.cs.auckland.ac.nz/$\sim$collberg/Research/Publications/CollbergThomborsonLow97a/index.html",
   URL       = {<a href="http://www.cs.auckland.ac.nz/collberg/Research/Publications/CollbergThomborsonLow97a/index.html"> Collberg97a </a>},
   ABSTRACT  = "
It has become more and more common to distribute software in forms 
that retain most or all of the information present in the 
original source code. An important example is Java bytecode.
Since such codes are easy to decompile, they increase the 
risk of malicious reverse engineering attacks.
\par
In this paper we review several techniques for technical 
protection of software secrets. We will argue that automatic 
{\em code obfuscation} is currently the most viable method 
for preventing reverse engineering. We then describe the 
design of a {\em code obfuscator}, a tool which converts a
program into an equivalent one that is more difficult to 
understand and reverse engineer. 
\par
The obfuscator is based on the application of code transformations,
in many cases similar to those used by compiler optimizers.
We describe a large number of such transformations, classify
them, and evaluate them with respect to their 
{\em potency} (To what degree is a human reader confused?), 
{\em resilience} (How well are automatic {\em deobfuscation} 
attacks resisted?), and 
{\em cost} (How much overhead is added to the application?).
\par
We finally discuss some possible deobfuscation techniques
(such as program {\em slicing}) and possible counter-measures
an obfuscator could employ against them."
      }