New Method To Detect and Prove GPL Violations

qwerty writes "A paper to be presented at the upcoming academic conference Automated Software Engineering describes a new method to detect code theft and could be used to detect GPL violations in particular. While the co-called birthmarking method is demonstrated for Java, it is general enough to work for other languages as well. The API Benchmark observes the interaction between an application and (dynamic) libraries that are part of the runtime system. This captures the observable behavior of the program and cannot be easily foiled using code obfuscation techniques, as shown in the paper (PDF). Once such a birthmark is captured, it can be searched for in other programs. By capturing the birthmarks from popular open-source frameworks, GPL-violating applications could be identified."

Comments

Other languages

[Mike McTernan]

I looked through the paper, and it is cool stuff. But I couldn't see where it supposed the system would work well for other languages, and I wonder if it really would be so good.

Java has a very large standard library that is always dynamically linked, and hence can easily be instrumented as the technique requires. C allows static linking which would make such hooking much more difficult. Additionally Java executes in a very standard environment due to the Virtual Machine, where as other languages may have varying ABIs type sizes and other properties that could add significant noise to the birthmark.

That said, system calls are always hookable and reasonably standard, so maybe this technique could be applied successfully there for malware detection or similar?

Re:new use of old trick

[Just Some Guy]

How did you know they were cheating and didn't derive their similar approaches from a common origin (presumably material that was presented in class or else from the textbook)?

Amen to that. This is an old story, but I think it bears repeating. A friend of mine and I got "caught" turning in identical code for an assignment. I mean, identical. Same structures, variables, types, layout - everything. However, we wrote our programs separately and never saw each others' until our teacher asked about it.

It sounds improbable, but consider that:

1. We both directly transcribed variable names from the homework assignment. A sentence like "it is a fatal error condition for the user to specify a negative number of tasks" became "assert(numtasks >= 0);".
2. We used the same editor and the same indenting style.
3. We had done much of our homework together in previous classes because we tended to take the same approach to solving problems.
4. The assignment wasn't terribly complex to begin with, so the resulting code was only a few pages long.

We had a teacher who trusted us and we were both good students with good test grades, so it was dismissed as a humorous coincidence. I'm glad a human was willing to listen to our explanation and not just go along with the findings of an automated tester.