 Open Access
 Total Downloads : 261
 Authors : Mrs. Madhavi Verma
 Paper ID : IJERTV3IS20743
 Volume & Issue : Volume 03, Issue 02 (February 2014)
 Published (First Online): 26022014
 ISSN (Online) : 22780181
 Publisher Name : IJERT
 License: This work is licensed under a Creative Commons Attribution 4.0 International License
Modern Image Security Mechanism using Hill and Vernam Cipher
Mrs. Madhavi Verma
Student M. Tech Information Security DIMAT Raipur
Abstract Image is most important multimedia digital content transfers over internet in todays modern communication network. It contains the confidential information, which protection is achieved by encryption. In this methodology, authors achieved image security by applying Hill Cipher and Vernam Cipher together on image. In this paper, I have done the literature review on existing work for image encryption with detail study of SDAIES and proposed my work to enhance existing method.

INTRODUCTION
In todays modern communication network, digital images and documents travel widely and rapidly, in multiple manifestations, through email and across internet. With increase use of internet in 21st century digital images are exchanged over various types of networks. These digital images contain confidential information. Controlling and protecting sensitive and confidential information in images has become an important aspect of today information security system. So image security is an important issue in communication and storage of images, and Encryption is a common technique to uphold image security.
Encryption
Original Image Cipher Image
Figure 1. Image Encryption
Image encryption techniques try to convert original image to another image that is hard to understand; to keep image confidential between users. It means whenever we want to send image to someone that should be encrypted in such a way that no one can decrypt without knowing the key of the decryption process.

DIFFERENCE BETWEEN TEXT AND IMAGE ENCRYPTION
To better understand the image encryption there is need to first analyze the differences between implementations for image data and text data encryption. Basically, there are some differences between image and text data encryption.

When Cipher text in produced, it must be decrypted to the original plaintext in a full lossless manner.
However, the cipher image can be decrypted to the original plain image in some lossy manner.

Text data are sequence of words. They can be encrypted directly by using block and stream ciphers. However, digital image are usually represented as twodimensional (2D) arrays. For protecting the stored 2D arrays of data with text processing algorithms, they must be converted to 1D arrays before using various traditional encryption techniques.

Because the storage space of a picture is very large, it is sometimes inefficient to encrypt or decrypt images directly. One of the best method is to encrypt/decrypt information that is used by image compression only for reducing both its storage space and transmission time.



BASIC CRYPTOGRAPHY TECHNIQUES
Encryption is the process of encoding message/images such that its meaning becomes not obvious; decryption is the reverse process: transforming an encrypted text/sound/data/image back into its normal form. A system of encryption and decryption is called a cryptosystem.
The art and science of keeping a message/image secure is cryptography, and it is practiced by cryptographers. Cryptography deals with the design and analysis of systems that provide secure communications or resist cryptanalysis.
Cryptanalysts are practitioners of cryptanalysis; the art and science of breaking Cipher text/image; that is, seeing through disguise. The branch of mathematics encompassing both cryptography and cryptanalysis is cryptology and its practitioners are cryptologists
A cryptographic algorithm, also called a cipher, is the mathematical function used for encryption and decryption. If the security of an algorithm is based on keeping the way that algorithm works a secret, it is a restricted algorithm.
The security of the modern cryptography is based on the key. The range of the possible values of the key is called the key space.
Cipher systems can be classified according to key into two types: secret key systems and public key systems.

Symmetric Key Cryptography

Asymmetric Key Cryptography
for all types of images improves the encryption security
* Overcome the problem of textured zones existing in other known
encryption algorithms
Image Encrypti on Using Self Invertible Key Matrix of Hill Cipher Algori thm
Matrix Based and Encrypt Gray Scale
component, then encrypt, then concatenate encrypted component
* Computational complexity can be reduced matrix
Overcom e the drawbac k of using a random key matrix
* Not applic able in image with backgr ound of same gray level or same color
* Suffered from known plain text attack
A New Image Encrypti on Appro ach using Combin ational Permut ation Techni ques
Symmet ric key crypto system using combin ed cryptogra phic algorithm s – Generaliz
ed
Clubbed both bit level and byte level generalized modified vernam cipher method with feedback
encryption
* Decryp tion proced ure need exact initial random matrix
* Time taking for large
text

For gray scale image encryption use modulus of 256

For Color image first decompose the color into RGB

Encrypt gray scale as well as color images

High Speed

High Throughput

Combin ation of different permutation techniques

Higher Entropy and Correlation between image elements decreased

Reduces the correlation between the pixel, bit or block of image

Higher entropy decreased

Permu tation process is too complex

Time taking

Chance of mistake is high

Bit level encryption

Byte level

Resistant to differential attack or known plain text attack

Effective for encrypting short message, password, confidential key

Brute force attack is not applicable

Symmetric Key cryptography
These algorithms encrypt and decrypt messages with a key in such a way that it is difficult to decrypt without the key. Because the encryption and decryption keys in a secretkey cryptosystem are the same, such systems are often called symmetric in the literature.
Most secretkey cryptosystems operate on messages one block at a time; a block may be 64 bits long, and the keys are usually short, say, 56 bits long. Ideally, an attacker's only approach is trial and error. Secretkey cryptosystems provide confidentiality and key management to parties who have previously agreed on a secret key.

Asymmetric key Cryptography

These algorithms encrypt and decrypt messages with two different keys in such a way that it is difficult to decrypt without the decryption key. The encryption key can be published without compromising security. And is called the public key for this reason; the decryption key is called the private key. Because the encryption and decryption keys in a publickey cryptosystem differ, such systems are often called asymmetric in the literature. The idea comes from Diffie and Hellman.
Publickey cryptosystems provide confidentiality and key management. They an be as secure as or more secure than secretkey cryptosystems, but they are generally slower. Their main advantage is that, since the encryption key can be published, parties need not first agree on a secret key. They are often combined with secretkey cryptosystems to gain the benefits of both: speed without prior secrets.


RELATED WORKS
In order to protect digital images from unauthorized users doing illegal reproduction and modifications, a variety of image encryption schemes have been proposed. Most of the algorithms specifically designed to encrypt digital images were proposed in the mid1990s.
One of the bestknown techniques has been credited to Moni Naor and Adi Shamir, who developed it in 1994. They demonstrated a Visual Secret Sharing Scheme where an image was broken up into n shares so that only someone with all n shares could decrypt the image, while any n 1 shares revealed no information about the original image. Each share was printed on a separate transparency, and decryption was performed by overlaying the shares. When all n shares were overlaid, the original image would appear.
Table 1. Comparison Table
Work
Methodology
Advantage
Disadvan tage
A
modified AES
based algorithm for image encrypt tion

A5/1 key stream generator

W7 key stream generator

W7 key stream generator improves the security of the AES algorithm

Better performance

The use of key stream generator

Time taking

Risky
modified Vernam Cipher method, MSA
method and NJJSAA
method: TTJSA
algorithm
* Exit
message
SDEI: A
Cryptogr aphic Techniqu e To Encrypt Images
Algorithm
ment
SDAEI:
An Advan ced Encryp tion Techniq ue For Images
Algorithm
randomiz ation
* Randomization process make it more secure
* Small range of rotation of bit
An Image Encrypti on Method: SD
Advance d Image Encrypti on Standard: SDAIES
Algorithm
iv. Modified MSA randomizatio
n
ranges

Rotation and reversal

Extended Hill Cipher using Involutory Matrix

Encrypt any image

Also able to encrypt stenographic image

Time taking

Bit and byte manipula tion need further enhance

Bit Rotation and reversal

Extended Hill Cipher using Involutory Matrix

Modified MSA

Upgraded version on SD EI

Take optimal amount of time to encrypt

Modified Bit Rotation and reversal technique using Nr

Extended Hill Cipher using Involutory Matrix

Generalized modified Vernam Cipher

Upgraded version of SD AEI

Inclusion of Vernam cipher make it more strong

Byte level encryption

Using effective number in Bit rotation and reversal process make more effective rotation

Bit rotation still has 06

Need more secure randomiz ation process

Time taking
4) Modified MSA Randomization for File Encryption

PROBLEM IDENTIFICATION IN EXISTING
METHODOLOGY
I analyze the all algorithm of the existing methodology and find some problem that are

In the first stage of the problem a code is generated from the given password which is of two digits. Therefore whatever password entered by the user will generate only two digit code which range from 10 to 99.

In bit rotation and randomization technique effective number generated by password is operated by modulus 7 i.e.
NR =N mod 7
Where, 7 is the number of iterations required to reverse entire input byte and N = [n1 + n2 + n3 + n4 +nj]. So there is only 7 type of randomization pattern in existing method.

In hill cipher we have to choose only self involutory matrix. While reading other image encryption technique came to know that most of image encryption algorithm is suffered from some of common problem e.g., time taking encryption process, pixel correlation not reduced much more, risky etc.


PROPOSED METHODOLOGY My objective in this project is

Enhancing its Bit rotation and reversal method by applying different key generation method

In previous work password randomization ranges only 1 to 7
i.e. only 7 type of randomization format possible so there is chance to two different password shows same type of randomization process. To overcome this problem I will apply/include some more parameters in randomization process
e.g. change process of random generation

I will try to extend Hill cipher by apply hill cipher twice on same input image.



EXISTING METHODOLOGY
SDAIES method is devised by Somdip Dey and it is itself a successor and upgraded version of SDAEI and SDEI image encryption technique. The four different encryption modules, which make up SDAIES Cryptographic methods, are as follows:

Modified Bits Rotation and Reversal Technique for Image Encryption

Extended Hill Cipher Technique for Image Encryption

Generalized Modified Vernam Cipher for File Encryption
Figure 2. Block Diagram of Methodology

DISCUSSION AND FUTURE SCOPE
In this paper, the author proposes a standard method of image encryption, which first tampers the image and then disrupts the file structure of the image file. This encryption method is very successful to encrypt the image perfectly to maintain its security and authentication. The inclusion of modified bits rotation and reversal technique, and modified Vernam Cipher along with feedback mechanism, made the system even stronger than it used to be before. In future, the security of method can be further enhanced by adding more secure bit and byte manipulation techniques to the system. Cryptanalysis attack can also perform on the this image encryption scheme. Addition of another security strategies makes it more secure than others techniques.
ACKNOWLEDGEMENT
I am very much grateful to Department of CSE, DIMAT to give me opportunity to work on image encryption. I sincerely express my gratitude to Mr. Akash Wanjari of Dept. of MCA, DIMAT for giving constant inspiration to complete this work. I am also thankful to Mrs. Preeti Tuli, Prof. Somesh Dewangan, Dept. of CSE, DIMAT for helping me directly and indirectly during this work. I am really thankful to my all friends for their blessing and support.
REFERENCES

M. Zeghid, M. Machhout, L. khriji, A. Baganne, and R.Tourki, A modified AES based algorithm for image encryption, World Academy of Science, Engineering and Technology 27, 2007, pp. 206211.

S.K. Panigrahy, B. Acharya, D. Jena, Image Encryption using self invertible key matrix of Hill cipher algorithm, 1st International Conference on Advances in Computing, Chikhli, India, 2122 Febururary 2008, pp. 14.

A. Mitra, Y.V. Subba Rao and S.R.M. Prasanna, A New Image Encryption Approach using Combinational Permutation Technique, World Academy of Science, Engineering and Technology, vol14, 2702 2008, pp. 842846.

Bibhudendra Acharya, Saroj Kumar Panigrahy, Sarat Kumar Patra, and Ganapati Panda, Image Encryption Using Advanced Hill Cipher Algorithm, ACEEE International Journal on Signal and Image Processing, Vol 1, No. 1, Jan 2010,pp. 3741.

D. Chatterjee, J. Nath, S. Dasgupta and A. Nath, a new symmetric key cryptography algorithm using extended MSA method: DJSA symmetric key algorithm, 2011 International Conference on Communication Systems and Neteorks Technologies, IEEE Computer Society, 2011, pp. 8994.

Somdip Dey, "SDEI: A Cryptographic Technique To Encrypt Images", Proceedings of The International Conference on Cyber Security, CyberWarfare and Digital Forensic (CyberSec 2012), held at Kuala Lumpur, Malaysia, 2012, pp. 2832.

Somdip Dey, "SDAEI: An advanced encryption technique for images", IEEE Second International Conference on Digital Information Processing and Communications (lCDIPC), 2012, pp. 6974.

Somdip Dey, "An Image Encryption Method: SDAdvanced Image Encryption Standard: SDAIES", International Journal of CyberSecurity and Digital Forensics (IJCSDF) 1(2), 2012, pp. 8288.

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Ankita P. Baheli, Lokesh Singh and Ashif Ullah Khan, A Comparative Literature Survey On Various Image Encryption Standards, International Journal of Engineering Research & Technology (IJERT), Vol. 2 Issue 4, April 2013, pp. 14441450.

Behrouz A. Forouzan, Cryptography and Network Security, Tata McGraw Hill Companies, India, 2007.

A. Uhl and A. Pommer, Image and vedio Encryption, Springer, 2005.

Fathi E. Abd ElSamie, Hossam Eldin H. Ahmed, Ibrahim F. Elashry, Mai H. Shahieen, Osama S. Faragallah, ElSayed M. ElRabaie and Saleh A. Alshebeili, Image Encryption: A communication Perspective, CRS Press, 2013.