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Reverse Engineering

Computer Science

D.I.A.T.M.

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Introduction �To�Reverse Engineering

By, Sonal Pravin

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Contents

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

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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

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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”

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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

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Forward Engineering �And�Reverse Engineering

By, Puja kumari

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What is Forward Engineering ?

Waterfall Model of software development

Requirement

Analysis

Design

Implementation

Testing and

Maintenance

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Forward Engineering

Requirements

Design

Source Code

Testing & Maintenance

In this slide ,we are dealing with different phases of forward engineering.

Software Requirement Analysis is also known as feasibility study. In this requirement analysis phase, the development team visits the customer and studies their system requirement. The next phase that is Design phase, the overall software structure and its outlay are defined.

Moving on to the next phase Code Generation phase, in code generation phase the design must be decoded into a machine-readable form so that the complier can easily compile the code, and hence the software product is ready for Testing and Maintenance phase. In testing phase, different testing methods are available to detect the bugs that were committed during the previous phases. Now moving on to the next slide you can understand difference between forward engineering and reverse engineering.

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Forward Engineering Vs� Reverse Engineering ?

Forward Engineering

Reverse Engineering

Requirements

Design

Source Code

Testing & Maintenance

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Concept of Abstraction System

Abstraction System

Old system

New System

Forward Engineering

Re-Implementation

Reverse Engineering

Abstraction

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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

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Benefits, Difficulties & Scope of�Reverse Engineering

By, Ayan Pradhan

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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)

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Benefits of Reverse Engineering

Benefits

maintenance cost savings
quality improvements
competitive advantages
software reuse facilitation

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Difficulties of Reverse Engineering

Gap between problem

/solution domain

Gap between concrete

and abstract

Gap between coherency/disintegration
Gap between hierarchical/associational

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Scope and Task of Reverse Engineering

program understanding

Problem/Application

domain

Program/Implemen.

domain

Mapping

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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.

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Discovery of Abstraction & Different Approaches� of Reverse Engineering

By, Sweta Sangam

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Discovery of Abstraction

Discovery of abstraction in large system

Maintenance purpose
Evolution purpose
Re-Engineering purpose

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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

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Different Approaches

Restructuring

Transformation from one representation to another at the same level,

Requirements

Design

Source code

Behavior

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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

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Different Approaches

Abstraction System

Old system

New System

Forward Engineering

Re-Implementation

Reverse Engineering

Abstraction

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Practical Implementation�& Tools of �Reverse Engineering

By, Debdeep Kundu

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Reverse Engineering Tools

Analysis Tools
Browsers
Object Server
Task Oriented Tools

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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

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Example--Java Decompiler

ClassCracker 2 Interface

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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.

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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…...

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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

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Example--Java Decompiler

ClassCracker 2.0--want to try it?

Free download at http://www.pcug.org.au/~mayon/classcracker/ccgetdemo.html
Only first three methods are decoded.

Bridge 1.0---Free

http://www.geocities.com/SiliconValley/Bridge/8617/jad.html

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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

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References

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

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THANK YOU

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Questions ?