A Plagiarism Detection Technique for Java Program Using Bytecode Analysis

1. A Plagiarism Detection Technique for Java Program Using Bytecode Analysis Presenter : Shu-Ya Li Authors : Jeong-HoonJi, Gyun Woo, and Hwan-Gue Cho ICCIT, 2008

2. Outline • Motivation • Objective • System overview • Methodology • Experiments and Results • Conclusion • Comments

3. Motivation • Plagiarism can be a big problem in universities and companies. • In MIT, about 30% of students were punished due to plagiarism. • Most plagiarism detection systems evaluate the similarity of source codes. • the source code security can be a significant problem.

4. Objectives Plagiarism detection g9623702.java g9623702.class g9623701.class g9623703.class Compiler Interpreter 0011010011101001… Class File (Bytecode) Source code • A new plagiarism detection technique for Java programs • Using bytecodes without referring their source codes.

5. System overview • (a) Generating token sequences • (b) Evaluating the similarity Class File (ByteCodes) Similarity Matrix Constant Pool Analysis Adaptive Local Alignment Similarity Measure Similarity Constant Pool Analysis Adaptive Local Alignment Similarity Measure Class Collection Class Collection Token Sequences ByteCode Grouping ByteCode Grouping ByteCode Linearization ByteCode Linearization Static Method Analysis Static Method Analysis Token Sequences

6. Bytecode Linearization ByteCode Grouping Pa Pb The results of linearization for two programs Pa and Pb ByteCode Grouping

7. Bytecode Linearization main() → sum() → min() sum() → main() Static Method Analysis

8. Adaptive Local Alignment & Similarity Measure bc_pushbc_store bc_pushbc_store bc_store - Local alignment algorithm -2 point +1 point Adaptive local alignment 根據keywords出現頻率 +1 point

9. Experiments

10. Conclusion we presented an automatic Java byte code comparison system PINTBfor detecting plagiarism in Java bytecodes.

11. Comments • Advantage • A new plagiarism detection method • Drawback • Application • Source code analysis