Obfuscation techniques in Java

1
Obfuscation techniques in Java

• Therese Berge
• Jonas Ringedal

2
Presentation

• Goal of the project
• Background
• Obfuscation techniques
• Tests
• Evaluation and results

3
Goal of the project

• Gain knowledge about different obfuscation
  techniques
• Find the best technique for us
• Testing existing programs
• Evaluating the techniques

4
Background

• Java increased the threat of reverse engineering
• High-level bytecode
• Platform independent
• Portable
• Anyone can have access to the bytecode
• Reverse engineering
• Analyse system to create higher level
  representation
• Recreate Java source code

5
Obfuscation techniques

• Layout Obfuscation
• Data Obfuscation
• Control Obfuscation
• Preventative Transformations

6
Layout Obfuscation

• Changing variables
• Removing comments
• Both methods
• Free of cost
• One way functions

7
Data Obfuscation

• Encoding
• for(int i 0 i lt 100 i )
• f(i) 2i5
• for(int i 5 i lt 205 i i2)
• Split array
• Change ordering
• Variable declaration spread out

8
Control Obfuscation

• Hide information flow
• Dead code
• Parallelize Code

9
Preventative Transformations

• Crash deobfuscators
• Use known weaknesses

Stealth

• Hide obfuscation

10
Tests

• Obfuscator JShrink
• Decompiler JAD
• Test code Password.java

Test results

• JShrink
• JAD from .class
• JAD from obfuscated code

11
Evaluation and results

• Obfuscators major tools for protecting Java
  programs from reverse engineering
• Hard to find free programs
• Layout Obfuscation not enough
• Best Combination of manually changed code,
  stealth and obfuscators.
• Goal achieved