Decompilation is a problem for the software industry, with the global revenue loss due to software piracy estimated to be more than $50 billion in 2008. There are several Java decompilers available but none are 100% effective, and many are obsolete/unmaintained. We found Java Decompiler, JODE and Dava to be good Java decompilers but not perfect. Dava is particularily suited to aribtrary bytecode, while others are suited to javac generated bytecode. Static watermarking techniques can be used to protect a program from being copied by giving the ability to easily identify the owner of such software. However, static watermarking techniques are higher susceptible to semantics-preserving transformations. We show that the majority of the current implementations of watermarking systems are based on static techniques are fail when attacked with obfuscations and optimisations. Further work will involve evaluating dynamic watermarking algorithms in a similar manner, and compare them to their static counterparts. Techniques such as program slicing can be used to attack software watermarks, in subtractive attacks on software.

1. Java Software Attacks & Defences James Hamilton, PhD Student 0 1 0 0 0 0 1 1 0 1 1 0 0 0 1 0 0 1 1 0 1 0 1 0 0 1 0 1 0 1 0 1 1 0 0 1 0 0 0 1 1 1 0 1

3. I tested 10 different decompilers with the latest Java class file format using 10 different test programs, extending a 2003 survey.

4. Assign a value to the decompiled programs depending on the accuracy of decompilation. software company software thief

8. Java Decompiler or JODE for javac bytecode Year 1 – Recap - Results

10. Leading conference in my field.

11. My first published paper 'An Evaluation of Current Java Decompilers'

12. Co-Located with 25 th IEEE International Conference on Software Maintenance

13. http://whoyouknow.co.uk/uni/phd/papers/JavaBytecodeDecompilerSurvey.pdf

15. Home to the huge University of Alberta - 50 city blocks with over 90 buildings

16. & West Edmonton Mall – the world's 5 th largest mall

18. Different decompilers for different problems

20. do we really need to perform type inference if the only condition is that we require re-compilable code?

21. are the problems with the Java decompilers fundamental or just bugs? Paper Conclusion Questions

24. Task 1 completed + decompilation of some other simple programs including for-loops, ifs, exception handling.

25. Cannot decompile all the test programs from my first paper.

26. Slow progress, currently on hold.

27. Extremely useful in understanding the problems of implementing a decompiler.

28. I found that ASM is probably not the best framework to use – the visitor API made some things hard to do.

29. Will probably port to Byte Code Engineering Library (BCEL) [3] [2] G. Nolan, Decompiling Java . APress, 2004. [1] http://asm.ow2.org/ [3] http://jakarta.apache.org/bcel/

30. Software Watermarking

32. But does provide a way to prove ownership of a program

33. Can prove the individual who copied the program (Fingerprint Mark)

34. Obfuscation aims to make a program hard to understand and/or decompile Software Watermarking vs Obfuscation

36. Allatori (Commercial)

38. 588 out of 840 combinations with watermarks embedded correctly

39. Obfuscated the watermarked programs with 36 obfuscations, 1 optimisation and 2 obfuscation combinations.

40. 23,626 correctly obfuscated

41. Attempted to recognise watermarks from all the obfuscated programs

43. http://whoyouknow.co.uk/uni/phd/papers/JavaBytecodeWatermarkingSurvey.pdf

44. International Conference on Software Engineering (ICSE) 2010 More details about my trip at http://whoyouknow.co.uk/uni/phd/icse2010/

46. 3 algorithms implemented in Sandmark.

47. Should be resilient to semantics-preserving transformations.

48. .

50. Range of views: borderline, weak reject, reject.

52. There is two evaluations in one

53. Didn't take into account space/time costs

54. Didn't analyse the interactions between obfuscation/watermark pairs

55. Programs might be too small/too similar (all were jEdit plugins)

57. Add the dynamic algorithms in Sandmark to the evaluation

59. Robustness of recognisers

60. Resilience to semantics preserving transformations

61. Space/Time costs

63. Compare dynamic vs static watermarks

65. Further work will include slicing watermarks (possibly linking with Sebastian's work on slicing)

66. Any questions? Thanks