This document discusses reverse engineering, which involves determining how a product works by analyzing it without prior knowledge of its design or requirements. It covers the definition of reverse engineering, why it is needed such as for software maintenance, and its scope and tasks. Different approaches to reverse engineering are presented, such as restructuring and design recovery. Finally, examples of reverse engineering tools for Java like decompilers are provided.

1. Reverse Engineering
Computer Science

2. Introduction
To
Reverse Engineering

3. CONTENTS
● What is Reverse Engineering (RE)?
● Why do we need Reverse Engineering?
● Scope and Tasks of Reverse Engineering
● Different Approaches
● RE tools
● Conclusions

4. WHAT WILL HAPPEN ?
●You have an unexpected case:
●You finished one course project using Java
●Your program runs OK
●But, by accident, you delete the java file

5. WHAT WILL HAPPEN ?
●You have an unexpected case:
●You finished one course project using Java
●Your program runs OK
●But, by accident, you delete the java file
●Solution is “Reverse Engineering”

6. WHAT IS REVERSE ENGINEERING?
●RE encompasses any activity that is done to
determine how a product works, to learn the
ideas and technology that were used in
developing that product.
●RE can be done at many levels
●RE generally belongs to Software Maintenance

7. FORWARD ENGINEERING
AND
REVERSE ENGINEERING
By, Puja kumari

8. WHAT IS FORWARD ENGINEERING ?
Waterfall Model of
software
development
Requirement
Analysis
Design
Implementation
Testing and
Maintenance

9. FORWARD ENGINEERING
Forward
Engineering
Requirements
Design
Source Code
Testing &
Maintenance

10. FORWARD ENGINEERING VS
REVERSE ENGINEERING ?
Forward Engineering Reverse Engineering
Requirements
Design
Source Code
Testing &
Maintenance

11. CONCEPT OF ABSTRACTION SYSTEM
Abstraction
System
Old system New System
Forward Engineering
Re-Implementation
Reverse Engineering
Abstraction

12. WHY DO WE NEED RE ?
●Recovery of lost information
●providing proper system documentation
●Assisting with maintenance
●identification of side effects and anomalies
●Migration to another hw/sw platform
●Facilitating software reuse

13. Benefits, Difficulties
& Scope of
Reverse Engineering

14. THE EARLY DAYS OF RE
●Law of Software Revolution (Lehman, 1980)
●Fundamental strategies for program
comprehension (Brooks, 1983)
●Taxonomy of Reverse Engineering (Chikofsky
&Cross, 1990)
●WCRE (Working Conference on R.E., 1990)

15. BENEFITS OF REVERSE ENGINEERING
●Benefits
●maintenance cost savings
●quality improvements
●competitive advantages
●software reuse facilitation

16. DIFFICULTIES OF REVERSE ENGINEERING
●Gap between problem
/solution domain
●Gap between concrete
and abstract
●Gap between coherency/disintegration
●Gap between hierarchical/associational

17. SCOPE AND TASK OF REVERSE
ENGINEERING
●program understanding
Problem/Applica
tion
domain
Program/Implem
en.
domain
Mapping

18. SCOPE AND TASK OF REVERSE
ENGINEERING
●Redocumentation and/or document
generation
●Recovery of design approach and design
details at any level of abstraction
●Identifying reusable components and
components that need restructuring
●Recovering business rules
●Understanding high-level system
description.

19. Discovery of Abstraction &
Different Approaches
of Reverse Engineering
By, Sweta Sangam

20. DISCOVERY OF ABSTRACTION
●Discovery of abstraction in large system
●Maintenance purpose
●Evolution purpose
●Re-Engineering purpose

21. LEVELS OF ABSTRACTIONS
●Application
●Application concepts, business rule, policies
●Function
●Logical and functional specification, non-functional
requirement
●Structure
●Data and control flow, dependency graphs
●Structure and subsystem charts
●Architectures
●Implementation
●Symbol tables, source text

22. DIFFERENT APPROACHES
●Restructuring
●Transformation from one representation to another
at the same level,
Requirements
Design
Source code
Behavior

23. DIFFERENT APPROACHES
●Reverse Engineering
●Design Recovery
●reproduce all the info for understanding the system
●Re-documentation
●provide different views of the system
●Re-Engineering
●first phase --understanding the system
●second phase--forward engineering

24. DIFFERENT APPROACHES
Abstraction
System
Old system New System
Forward Engineering
Re-Implementation
Reverse Engineering
Abstraction

25. Practical Implementation
& Tools of
Reverse Engineering
By, Debdeep Kundu

26. REVERSE ENGINEERING TOOLS
●Analysis Tools
●Browsers
●Object Server
●Task Oriented Tools

27. EXAMPLE--JAVA DECOMPILER
●How to recover bytecode from .class file
under Unix/Win with JDK?
% javap -c <filename>
% javap -help (to see the options)
●Java Decompilers
●”ClassCracker” http://www.pcug.org.au/~mayon/
●“DeCafe Pro" from DeCafe, France at
http://decafe.hypermart.net/index.htm
●“SourceAgain" from Ahpah corp at http://www.ahpah.com

28. EXAMPLE--JAVA DECOMPILER
●ClassCracker 2 Interface

29. EXAMPLE--JAVA DECOMPILER
●Components of ClassCracker 2
● Java decompiler
●retrieves Java source code from Java class files
● Java disassembler
●produces Java Assembly Code
●A Java class file viewer
●displays Java class file structures.

30. EXAMPLE--JAVA DECOMPILER
●Features of ClassCracker 2
●User visual interface.
●Can decompile class files within zip or jar files.
●Conversion mode (JAVA, JASM or JDUMP) is
selectable
● A Batch Mode allows multiple class files to be
decompiled simultaneously
●more…...

31. EXAMPLE--JAVA DECOMPILER
●ClassCracker 2 System Requirements
●All platform (Window/ Linus /Unix)
●JDK /JRE
●Do not believe it?
●From myClass_origin.class ==>myClass.java
●% javac myClass.java (==>myClass.class)
●% diff myClass.class myClass_origin.class

32. EXAMPLE--JAVA DECOMPILER
●ClassCracker 2.0--want to try it?
●Free download at
http://www.pcug.org.au/~mayon/classcracker/cc
getdemo.html
●Only first three methods are decoded.
●Bridge 1.0---Free
●http://www.geocities.com/SiliconValley/Bridge
/8617/jad.html

33. CONCLUSIONS
●Reverse Engineering is a new research area
among software maintenance
●RE includes activities of understanding the
system and recovery info from system
●Program understanding is the most important
subset of Reverse Engineering
●Discovery of abstraction is key issue

34. REFERENCES
●http://www.wiley.com/WileyCDA/WileyTitle/
productCd-0764574817.html
●http://www.google.com
●- http://jode.sourceforge.net

35. THANK YOU

36. QUESTIONS ?