@TECHREPORT{CollbergThomborson98e,
   AUTHOR    = "Christian Collberg and Clark Thomborson",
   TITLE     = "On the Limits of Software Watermarking",
   MONTH     = aug,
   YEAR      = 1998,
   NUMBER    = 164,
   NOTE      = "http://www.cs.auckland.ac.nz/$\sim$collberg/Research/Publications/CollbergThomborson98e/index.html",
   URL       = {<a href="http://www.cs.auckland.ac.nz/collberg/Research/Publications/CollbergThomborson98e/index.html">CollbergThomborson98e  </a>},
   ABSTRACT  = "
Watermarking embeds a secret message into a cover message. 
In media watermarking the secret 
is usually a copyright notice and the cover a digital 
image. Watermarking an object discourages intellectual 
property theft, or when such theft has occurred, allows 
us to prove ownership. 
\par
The Software Watermarking problem can be described
as follows. Embed a structure W into
a program P such that: W can be reliably located and 
extracted from P even after P has been subjected to 
semantics preserving transformations such as code 
optimization and obfuscation; W is stealthy; W has 
a high data rate; embedding W into P does not 
adversely affect the performance of P; 
and W has a mathematical property that allows us to 
argue that its presence in P is the result of deliberate 
actions.
\par
In the first part of the paper we construct an
informal taxonomy of software watermarking 
techniques. In the second part we formalize these 
results. Finally, we propose a new software watermarking
technique in which a dynamic graphic watermark is stored 
in the execution state of a program. "
      }