On the Limits of Software Watermarking



Christian Collberg, Clark Thomborson

Department of Computer Sciences
The University of Auckland
Private Bag 92019
Auckland, New Zealand.
{collberg,cthombor}@cs.auckland.ac.nz


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.

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.

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.


This report is superseded by the article Software Watermarking: Models and Dynamic Embeddings.

See also the articles Manufacturing Cheap, Resilient, and Stealthy Opaque Constructs and Breaking Abstractions and Unstructuring Data Structures.



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