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.
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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
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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
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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:
Original
text
Cover-object,
C
F(X,M,K)
Message,file
M
Encrypted
Stego Object, Z
Stego-key, K
Fig 4.1: Steganography combined with encryption
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
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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 coverobject 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.
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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
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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.
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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
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
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
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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, unitintegration 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.
Fig 6.2.1: RAD model
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7 USECASE DIAGRAM
Fig 7.1: Usecase Diagram
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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.
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9 PROJECT SCHEDULE
Fig9.1: Gantt Chart
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10 CONCLUSION
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 wellfunctioning 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.
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REFERENCE

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.
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