1 INTRODUCTION

Steganography is derived from Greek words: steganos meaning covered/secret

and graphy meaning writing. So, it is defined as the art and science of hiding

information by embedding messages within seemingly harmless messages. It also

refers to the “Invisible” communication. The power of Steganography is in hiding

the secret message by obscurity, hiding its existence in a non-secret file.

Steganography works by replacing bits of useless or unused data in regular

computer files. It leaves behind detectable traces in the stego objects and modifies

the statistical properties. This hidden information can be plaintext or ciphertext

and even images.

In an image Steganography, it uses some reliable Steganography algorithms or

secret keys to transform or encrypt secret images into ciphered images. Only the

authorized users can decrypt secret images from the ciphered images. The

ciphered images are meaningless and non-recognizable for any unauthorized users

who grab them without knowing the decryption algorithms.

In our project, we aim to develop an application for police department or secret

service like organizations where the communication needs to be confidential in

order to prevent information leaks about their ongoing investigation on cases, task

assignment, working strategy etc. It provides a user friendly environment for the

secret service personnel to type their message, encrypt the written text and save

the encrypted text in a .txt file which can then be used to hide inside an image file

using steganographic technique. On the other hand the receiver can use the

application to retrieve the .txt file hidden inside the image and hence decrypt the

actual message from the retrieved file containing encrypted message. It allows the

use of webcam for taking snapshots of the criminals. For encryption of the

original message, AES (Advanced Encryption Standard) is used and for hiding the

txt file inside the image SDSA (Spatially Desynchronized Steganography

Algorithm) is chosen.

1

2 OBJECTIVES

The chief objectives of the project are:

i) To encrypt the message to be transmitted

ii) To use image steganography in police department

iii) To keep confidential details hidden during information exchange

iv) To securely communicate important messages

v) To practically implement image processing knowledge

2

3 FEATURES

The major features of the project are listed below:

i) Encryption and Decryption of text files

ii) Web-cam function for image capture

iii) Hide encrypted confidential details within the image

iv) Use of Spatially Desynchronized Steganography Algorithm(SDSA) and

Advanced Encryption Standard(AES)

v) Secure information exchange for police and security service like sector

3

Cover-object, C

Message, M

Stego-key, K

F(X,M,K)

Stego Object, Z

4 LITERATUREREVIEW

Invisible ink, a form of steganography, has been used for centuries. George Washington used it to spy against the British during the American Revolution and it was extensively used during World War II. It continues to be used today not only by spies but for commercial purposes, e.g. marking dice, chips and gaming equipment to protect against counterfeiting. The organizations that work in crime and security sectors such as police, army, secret services, FBI, CIA etc. have been following various techniques to communicate like emails, telephone which are more prone to attacks by the eavesdroppers and call tappers. Sometimes, the message to be transferred is even encrypted so that even if the outsiders succeed to receive the message they become unable to read the original content. Still, the fact is not hidden that the ciphertext contains some confidential information. Now, they have been driving their attention towards steganography whereby they can easily hide secret informations inside other cover objects which can be anything in today’s digital world such as image, audio, video etc. Keeping this in mind, we have been doing this project in order to hide confidential messages forwarded from one place to another encrypted and hidden inside image file so that no information leaks occurs. Despite the fact that cryptography and steganography are basically not the same, we apply the combination of both these techniques in order to achieve better results for security.

Basically, the model for steganography for encrypted file can be represented as:

Fig 4.1: Steganography combined with encryption

4

Encrypted file

Original text

Original text is the data that the sender wishes to remain it confidential. It can be

encrypted using any encryption techniques, particularly we follow Advanced

Encryption Stantard (AES) to convert to ciphertext that can be embedded in a bit

stream. Password is known as stego-key, which ensures that only recipient who

know the corresponding decoding key will be able to extract the message from a

cover-object which is an image file in case of image steganography. The cover-

object with the secretly embedded message is then called the Stego-object. Image

Steganography has been done using various algorithms such as least significant bit

(LSB) modification, masking and filtering etc. But our project will follow

Spatially Desynchronized Steganography Algorithm (SDSA) and so far it has not

been used in police department to hide any police details.

5

5 SYSTEM REQUIREMENTS

5.1 Hardware Requirements

Personal Computer

Webcam

5.2 Software Requirements

C#, .NET Framework

Database: MsSQL 2008

Microsoft Visual Studio

Microsoft SQL Server

6

6 METHODOLOGY

Our application is basically a desktop application that is specially designed for

police department where the department head has the full authority to all the

services since he is the administrator of the application. After login verification

for admin, he can write some information, encrypt the secret information thus

forming ciphertext and then hiding the ciphertext containing file in the image of

any kind. Other officers working in the same police station if get forwarded the

stego-image, only that particular message can be decrypted by the same officer

and if the image has been forwarded to any other station head, he can not only

unhide and decrypt the file but also reply for the message in the same way hiding

encrypted file in image. The staff in the station can use the webcam to capture

criminals photograph for criminal records and also keep police officers’ records in

database so that the information can be retrieved easily whenever required.

The staff responsible for such data entries can have access only to database stuffs

like adding, editing, deleting records and nothing others such as encryption and

hiding inside image.

6.1 Algorithms

6.1.1 Spatially Desynchronized Steganography Algorithm (SDSA)

Domain separation (or randomization) is a technique which is used for hiding the

embedding domain from the attacker. It is observed that existing domain

randomization techniques cannot provide enough randomization such that they are

easily be detected by recent steganalysis techniques. SDSA algorithm is less

detectable against the calibration based blind as well as targeted steganalytic

attacks than the existing JPEG domain steganographic schemes. The SDSA uses

blocks of 8x8(m x n) to embed the document in the carrier image in specific stego

chunks which are returned back to the image. SDSA is based on spatial block

desynchronization to disturb the successful prediction of cover image statistics

from the stego image.

7

Fig 6.1.1.1: Spatial block desynchronization

6.1.2 Advanced Encryption Standard (AES)

AES is a specification for the encryption of electronic data established by the U.S.

National Institute of Standards and Technology (NIST) in 2001. It is based on the

Rijndael cipher developed by two Belgian cryptographers, Joan Daemen and

Vincent Rijmen. AES is a symmetric block cipher that is intended to replace DES

as the approved standard for a wide range of applications. For AES, NIST selected

three members of the Rijndael family, each with a block size of 128 bits, but three

different key lengths: 128, 192 and 256 bits. The key size used for an AES cipher

specifies the number of repetitions of transformation rounds that convert the input,

called the plaintext, into the final output, called the ciphertext. The number of

cycles of repetition are as follows:

10 cycles of repetition for 128-bit keys.

12 cycles of repetition for 192-bit keys.

14 cycles of repetition for 256-bit keys.

Four different stages are used, one of permutation and three of substitution:

Substitute bytes: Uses an S-box to perform a byte-by-byte substitution of

the block

8

ShiftRows: A simple permutation

MixColumns: A substitution that makes use of arithmetic over GF(28)

AddRoundKey: A simple bitwise XOR of the current block with a portion

of the expanded key

Fig 6.1.2.1: AES algorithm

9

6.2 Software Development Life Cycle (Rapid Application Development- RAD)

Rapid application development (RAD) is a software development methodology that uses minimal planning in favor of rapid prototyping. The "planning" of software developed using RAD is interleaved with writing the software itself. RAD involves iterative development and the construction of prototypes. The four phases of RAD are:

Requirements Planning phase – It combines elements of the system planning and systems analysis phases of the Systems Development Life Cycle (SDLC). It ends when the team agrees on the key issues and obtains management authorization to continue.

User design phase – During this phase, users interact with systems analysts and develop models and prototypes that represent all system processes, inputs, and outputs. User Design allows users to understand, modify, and eventually approve a working model of the system that meets their needs.

Construction phase –In RAD, users continue to participate and can still suggest changes or improvements as actual screens or reports are developed. Its tasks are programming and application development, coding, unit-integration and system testing.

Cutover phase – It resembles the final tasks in the SDLC implementation phase, including data conversion, testing, changeover to the new system and user training.

10

Fig 6.2.1: RAD model

7 USECASE DIAGRAM

Fig 7.1: Usecase Diagram

11

8 DEVELOPMENT STATUS

8 .1 Work Accomplished

At this moment we have completed the basic layout of our project. We have

created entry form for storing the officer and criminal records. Database design

for keeping the records of login details, officer and criminal information, file sent

details etc. has been accomplished. More importantly, encryption of typed text,

writing ciphertext to txt files and decryption of the file contents have been

completed. Since our major task is to encrypt information and then hide the file in

cover image, it adds 35-40% of the work accomplished.

8.2 Work Remaining

About 60% of work is still remaining. The main objective of our project is to use

steganography in order to hide the information i.e to make the secure

communication amongst the department members. We now are working and

researching in this topic. The core part of the project is hence left untouched. Also

we tend to develop a working and complete application for police department

which is still in ongoing development phase.

8.3 Problems Encountered

The main problem encountered is to decide an application area where we can use

image steganography. As the project is being done in C# and .NET programming

language which is new for us, we have to study it well. So, different problems

were encountered during the project development. Making the concept vivid and

deciding how to develop the system was the most time consuming part. Also it

was time consuming to decide which algorithm to use for cryptography and

steganography. Since these topics are quite new for us, we find it difficult how the

chosen algorithm actually works.

12

9 PROJECT SCHEDULE

Fig9.1: Gantt Chart

10 CONCLUSION13

Steganography means hiding message inside a cover message. Steganography and

cryptography are closely related but their goals are different. In cryptography, the

data is encypted and unreadable but the existence of data is not hidden whereas

steganography leaves no evidence of the existence of data. Steganography and

cryptography can be used together to produce better protection. In a digital world,

both Steganography and cryptography are intended to protect information from

unwanted parties.

Basically, digital images are well-known to be used as a cover object to hide a

secret message. The proposed project is the application of image steganography in

police department to hide confidential police details inside image file. Various

techniques are widely used for this purpose but we are attempting to use Spatially

Desynchronized Steganography Algorithm (SDSA). It causes slight loss in cover

message but is not detectable to human eye. What is important is the preservation

of the hidden message. The stego-image is decrypted using stego-key generated

by the same algorithm to separate and securely extract the embedded files. Also

AES algorithm encrypts and decrypts the contents of text files using same key

since the algorithm is symmetric.

Steganography can be used to hide important data inside another file so that only

the authorized person intended to get the message even knows a secret message

exists .It is better technique for information hiding in the digital images with the

encrypted form. To conclude, our application would be user friendly and well-

functioning to produce ciphertext from the actual information and hide besides a

cover image and it would definitely be practically applicable in several sectors

where secret message transfer is required. Also this technique can be applicable

to deliver required confidential matter even through social networking sites where

people will not even think that the image could hold something else.

REFERENCE14

J. J. Eggers, R. Bauml, and B. Girod, “A communications approach to image steganography”, in Proc. SPIE Security and Watermarking of Multimedia Contents IV.

J. Fridrich, M. Goljan, and D. Hogea,“Steganalysis of JPEG Images: Breaking the F5 Algorithm”, in Proc. 5th International Workshop on Information Hiding, Noordwijkerhout, The Netherlands.

J. Fridrich, T. Pevny, and J. Kodovsky, “Statistically Undetectable JPEG Steganography: Dead Ends, Challenges, and Opportunities”, in Proc. ACM Multimedia and Security Workshop, Dallas, TX.

Ã, A. C., Condell, J., Curran, K., & Kevitt, P. M. (2010). Digital image steganography : Survey and analysis of current methods. Signal Processing, 90(3), 727–752. doi:10.1016/j.sigpro.

Westlund, Harold B. (2002). "NIST reports measurable success of Advanced Encryption Standard". Journal of Research of the National Institute of Standards and Technology.

Westlund, Harold B. (2002). "NIST reports measurable success of Advanced Encryption Standard". Journal of Research of the National Institute of Standards and Technology.

15