Busi Penchala Narasaiah* et al. ISSN: 2250-3676 [IJESAT ...€¦ · Other various encryption...

Busi Penchala Narasaiah* et al. ISSN: 2250-3676

[IJESAT] [International Journal of Engineering Science & Advanced Technology] Volume-4, Issue-5, 400-409

Busi Penchala Narasaiah,

PG Scholar,

Department of CSE,

SITAMS, Chittoor - 517127

[email protected]

Naresh Babu M M Assistant Professor,

Department of CSE,

SITAMS, Chittoor - 517127.

[email protected]

IJESAT | Sep-Oct 2014 400 Available online @ http://www.ijesat.org

Abstract—In the current digital era, the hasty booms in digital multimedia and network have paved ways for

people to utilize multimedia information. Since, the multimedia is used to develop an individual or a firm so it can

also be used to hinder the equivalent. This type of multimedia always experience threat regarding secure

communication. Hence, the multimedia security has become a major concern needs to be addressed in an expedient

manner. It is essential to encrypt multimedia before transferring it from one place to another due to complexity of

network.

The encryption methods have got high impact now days. But, it has been observed that various RGB[1]

image pixels are far related to adjoining pixel which is also called as correlation of pixel and this correlation of the

pixel enables an unauthorized user to predict about the value of nearby pixels. If somehow this correlation

concerning pixels can reduce then there will be an ease for encrypting image but it could not mean that reducing

correlation is adequate for encryption. Moreover correlation plays an imperative part to guess for original image.

In this paper we propose a new technique to reduce the correlation between the pixels and further, encryption

using a novel median statistics framework which will be helpful for sender and receiver for secure transmission of

multimedia. The proposed encryption scheme shows a good encryption results, is lossless and also has higher PSNR

ratio.

Index Terms—Encryption, Median statistics, Exploding, secured communication. (Key words)

I. INTRODUCTION

During some decades the use of internet has increased exponentially in various fields like, medical science, research,

commerce, education community and many more and the information security becomes the top priority. This crucial

information cannot be in a simple or bare format. Consider a case of secure transmission of image between the two

parties and suddenly an intruder get into the channel and uses that image for the something unethical i.e. deforming

it, or changing something which will lead to some serious trouble for either of the party. So, whenever there is

chance for interception or exposure by an individual and who does not have a need to know the encryption is used.

Encryption Decryption

Figure1.1: Symmetric Encryption Process

Encryption is the science of using mathematics based transformation to encrypt or decrypt data.Encryption

is used to prevent data from the unauthorized access which reduces the probability of unauthorized access several




times and only the authorized personnel‟s having the key is allowed to access it. But it cannot stop an insider

(employee, physician, vendor, business partner, etc.) from abusing privileges to access confidential information.

Other various encryption algorithm namely RSA[2], DES[3] etc. are very well for encrypting textual data

but as far as the image encryption is concerned it uses more memory as well as take more time because of bulk

image data. It should be noted that these encryption and decryption operations are guided by specific keys, where

the keys may be same or one can be easily derived from the knowledge of the other. Such cryptographic techniques

are grouped under private key cryptography [4], [5]. Alternately, encryption and decryption keys may be different or

computationally it may not be feasible to derive one key even though the knowledge of other key is available, and

such cryptographic methods are known as public key cryptography [3].

The good encryption scheme is the scheme which is provides both privacy and security and is losses. In

addition to this it should be tough enough to have minimum impact of the hacker. But now a days the hackers are

really smart and they usually find the correlation (if encryption not done properly) and easily get the access to the

information. Hence correlation plays an important role in image encryption. Correlation between the surrounding

pixel values in the image makes the image decryption process or guessing of plain image form a cipher image a bit

easy. So it is important to reduce the correlation between the image surrounding pixels and increase the degree of

randomness of the image.

In order to decrease the high correlation among the pixels and increase the entropy value of the image, we

propose a process based on the shifted rows and columns of the image using the (1:2:3 rule) technique. The shifting

process will be used to divide the original image into a number of blocks (n pixels by n pixels) that are then shifted

through the rows and columns wiling the image and then to feed into a next level of encryption which is global and

local encryption using novel median approach.

The distortion scores of pixels are determined by the occurrence frequencies of n X n patters in exploded

image. The novel encryption strategy allow different images(binary images, gray scale images, and medical images,

three component color images) to be encrypted and difficult to be decoded. This allows encrypted objects to be

protected with high level of security.

Hence in this paper we introduce the pixel rearrangement scheme which reduces the correlation and

increases the degree of randomness between the surrounding pixels. The proposed work uses the displacement of the

various horizontal and vertical strips by using (1:2:3) rule for reducing correlation and increasing entropy. The inter

pixel shifting of values change the entire image so that it contains the minimum clues of guessing the original plain

image. After deducting correlation a novel encryption technique was applied namely Median Statistics. Median

statistics has found many applications in engineering and mathematics. Thus by implementing the median statistics

and encryption keys a high level of security can be achieved which will make it too difficult for the hacker to

recognize the encryption technique.

This paper has the following structure: section II is about related works, section III is on the methodology

employed for the encryption and the decryption process of the digital images, section IV presents the mathematical

algorithms employed to come out with a ciphered image for the encryption process. Section V Results and analysis

of the ciphered mages obtained from the implementation of the algorithm used in the encryption process, and section

VI concluded the paper.

II. BACKGROUND

Ms. Ankita P. Baheti has given a literature review on various Image encryption standards according to her a

efficient encryption is very tough job. As per her survey Blowfish has better encryption scheme than other

algorithm. Moreover 3DES has the least performance among all the algorithms among Secret-key cryptosystem,

Public-key cryptosystem, digital signature schemes, Key-agreement algorithms, cryptographic has functions,

Authentication codes, symmetric key algorithms, data encryption standards,triple DES, Advance Encryption

standards, Modified AES, Image Encryption using block based transformation Algorithm ,Permutation based

encryption scheme etc.[6]

NehaKandekde, ShrikantTiwari introduced a technique which is combination of 3 different algorithms

which is based on the division of string, operation using magic square matrices, rotation operation on matrix and

also base conversion using key derived from the string.[7]

Ahemed Bashir Abugharsa had given a way to highly disturb the correlation between the image

pixels.They basically created different diffusion model by shifting table using a hash function and then used the

shifted table result from the first step for encryption for more efficient result.[8]




A.Mitra, Y, V, SubbaRaoand R.M.Prasanna together given a random approach which reduces correlation

among the bits, pixel and block using certain permutation techniques. And justified that the permutation of bits is

more effective and permutation of blocks and pixel are good for different level of security. And also explained that

the combined method is good relative to the individual permutation techniques.[9]

UmashankarPandey and Manish Manoria proposed an algorithm based on block based transformation using

shuffle operation followed by a new encryption algorithm and compared the result obtained with various algorithm

like RC6, AES and BFS on the basis of entropy and correlation.The result shows that the correlation between the

images decreased significantly.[10]

Researchers G.A.Sathishkumar and Dr. K,BhoopatiBagan proposed a algorithm which is a combination of

block permutation,pixel permutation and value transformation.[11]

Pooja Mishra and BijuThankachantogether given the review on the various encryption and Key selection

technique and hence concluded that there are so many techniques to make image secure So same techniques can be

used for encryption of selective part of image and some other technique can encrypt the remaining part or whole

image.In addition to this researchers also accept that each technique has its own suitable area.[12]

Quist_AphetsiKester introduced an encryption scheme for medical images which are closely related based

on pixel shuffling and a secret key generation.[13]

Mintu Philip utilized chaos- based encryption scheme using logistic map. This is done by utilizing discreet

wavelet transform for compression first and further chaos based algorithm encrypts image pixel by pixel by taking

the value of previously encrypted image. Researcher appreciates the fast and secured characteristics of the algorithm

and hence advised it to be used in real time application which have bandwidth and power constraints and also to

videos.[14]

Manjunath Prasad and K.L.Sudha proposed an encryption algorithm based on pixel scrambling where in

the randomness of the chaos is made utilized to scramble the position of data, The poisons of data is scrambled in

the order of randomness of the elements obtained from the charioted map and vice versa for decryption

process.They proposed a new algorithm which utilizes the single map against the four map used in Nien, H.H work

for Hybrid image encryption using multi chaos system.[15]

HiralalRathod, Mahendra Singh Sisodia, Sanjay Kumar Sharma introduced a Hyper Image Encryption

algorithm (HIEA). Here the image is first exploded into no of blocks of 10X10 sizes and further the proposed

encryption algorithm is applied.[16]

Abhshek Mishra, Ashutosh Gupta and DamodarRaicombinedly presented an algorithm use the chaotic

system properties like loss of information and are sensitive to initial condition.[17] Considering the prime weakness in the above mentioned methods, we propose a new technique to this

problem in which instead of considering the whole image as one to work upon, we slice the image[18] we are

dividing image in various horizontal and vertical slices and shifting them which will further reduce correlation and

hence increase encryption index.

III. PROPOSED ALGORITHM

This presented work includes some basic statistical methods. The mean of can be defined as the average pixel value

of an image in consideration mathematically the image mean „α‟ can be given by the formula

𝛼 =1

𝑛 ∗ 𝑚 𝑖𝑚(𝑥, 𝑦)

𝑚

𝑦=1

𝑛

𝑥=1

Where „α‟ is the image mean and „im‟ is the digital image in consideration of sizem*n‟.Further this statistical

function is used for the condition that the pixel could be merged or not.

In this section, we introduce a novel encryption algorithm based on horizontal vertical shift (exploding) and median

statistics for global and local environments has been utilized. The encryption completes in four steps. The general




structure of the encryption process is presented in the figure. The basic components of the proposed encryption

framework are proposed as follows

A. Inputs

Input Image. The input image may be of any image format using the 8-bit, power of two‟s representation.

B. Horizontal Shift(exploding)

The horizontal column of specified size gets shifted using rule 1:2:3i.e the first block is moved to second

place, second block is shifted to the third place and the third block is shifted to sixth position and so on.

C. Vertical Shift(exploding)

The vertical column of specified size gets shifted using rule 1:2:3i.e the first block is moved to second

place, second block is shifted to the third place and the third block is shifted to sixth position and so on.

D. Encrypt local

The image is exploded in the block of size (n by n) and then by choosing the center pixel of the block

(median pixel) the block is encrypted based on some condition.

E. Encrypt global:

The center pixel of whole of the image is chosen and all the remaining pixels are encrypted based on

condition.

The encryption algorithm is as follows:

Level 1: In first level of encryption the image is exploded into various horizontal blocks of specified size

using rule 1:2:3.That means the first block is moved to second place, second block is shifted to the third

place and the third block is shifted to sixth position and so on.

Level 2: Horizontally same as first level

Level 3 In third level of encryption median based approach is applied globally

1) Initially the key pixel of the image is computed based on the median based approach. In the

above stated matrix we have chosen the center pixel as the key pixel for encryption.

2) Then a difference of each pixel with the key pixel is computed.

3) Further based on a condition the value of each of the surrounding pixel is modified by adding or

subtracting 256 from the surrounding pixel.

4) These modified changes are then reflected to the original image or part of image.

Level 4:

In the fourth level of encryption the globally modified image is further modified by the median

method but this time the scheme is implemented locally on the separate 3X3, 5X5,6X6, …… ,(n-

1) x (n-1) block size.

1) In second level of encryption the first leveled encrypted image is divided into 3X3, 5X5,6X6,

(n-1) x (n-1) block size.

2) Then further this time key pixel of the image is calculated for each block using median based

approach.

3) Then a difference of each pixel with the key pixel is computed block by block.

4) Further based on a condition the value of each of the surrounding pixel is modified by adding or

subtracting 256 from the surrounding pixel.

5) These modified changes are then reflected to the original image or part of image.




Level 1 Encryption

1

2

3

4

5

6

Image Horizontal and Vertical Shift Using (1:2:3) rule

Calculate Size and No of pixel of the image and Horizontal and

vertical pixel of block

Selection of key pixel by Median Based Approach

If diff<0 Set new value

Divide the Image into ‘n’ pixel block based on ‘size’ Size2

11111111

Selection of key pixel by Median Based Approach for each block

if diff<0

Image with local and global encryption with

median method

Level 2 Encryption

End

Y N

2

3

4

5

6

Input Image Chrysanthemum.jpg

Flower.jpg

Image Data

Calculate Size and No of pixel of the image and Horizontal

and vertical pixel of block

Divide the Image into ‘n’ pixel block based on ‘size’

Size1

11111111 H

1

H

2

H

3

H

4

H

5

H

6

H

7

Start

Set new value

Set new value

Set new value




IV. COMPUTER SIMULATION

In this section, the simulations results of proposed system are presented and analyzed. Computer simulations were

simulated using MATLAB software package was done using 50 color images varying in size classes of image

features. The images which uncompressed TIFF are converted into color or gray images that are further used for

encryption. The simulation process on the test imagesout in different phases. We present simulation results for six

different classes of colorimages.

Figure 4.1 Simulation of 6 Images for proposed methodology




Figure 4.2(a) Original Image (b) Histogram for R-layer(c)Histogram for G-layer (d)Histogram for B-layer

Figure 4.3(a) Vertical Shift using Rule 1:2:3 (b) Histogram for R-layer(c)Histogram for G-layer (d)Histogram for B-layer

Figure 4.4(a) Horizontal Shift using Rule 1:2:3 (b) Histogram for R-layer (c)Histogram for G-layer (d)Histogram for B-layer

Figure 4.5(a) Global Median Encryption (b) Histogram for R-layer(c)Histogram for G-layer (d)Histogram for B-layer

Figure 4.6(a) Local Median Encryption (b) Histogram for R-layer(c)Histogram for G-layer (d)Histogram for B-layer

In Figure 4.2 the histogram of for three layers are shown. The vertical and horizontal shift i.e. Figure 4.3 and Figure

4.4 clearly specifies that there is no alteration in the pixel value in the histogram since it is only about shifting the

pixel using (1:2:3)rule to reduce correlation. Further the proposed novel median approach is applied and the




histogram changes observed which almost the mirror image of the original one. Furthermore the operation is applied

locally and the proposed method based on median statistics offers a similar first order statistics (histogram) .for all

the three layers(R, G, B) as illustrated in Figure 4.6. In order to test the invulnerability of the system we verified it

by performing trials shown in Table 4.1 to 4.6.

Table 4.1 „Chrysanthemum.jpg‟

Table 4.2„Flower.jpg‟

Table 4.3 „Kola.jpg‟

Table 4.4 „Penguins.jpg‟

Table 4.5 „Jellyfish.jpg‟

Block Size RMSE PSNR RMSE after decryption PSNR after decryption

Primary Secondary R G B R G B R G B R G B

2 3 141.51 148.87 152.66 2.55 2.33 2.22 0 0 0 0 0 0

8 3 145.71 146.89 149.71 2.43 2.39 2.31 0 0 0 0 0 0

16 32 138.70 142.20 147.30 2.64 2.53 2.38 0 0 0 0 0 0

32 32 144.56 146.69 149.56 2.46 2.40 2.31 0 0 0 0 0 0

32 16 147.93 146.47 148.62 2.36 2.40 2.34 0 0 0 0 0 0

64 32 141.80 145.53 148.62 2.54 2.43 2.34 0 0 0 0 0 0

32 64 145.17 141.46 149.37 2.44 2.55 2.32 0 0 0 0 0 0



2 3 137.48 137.76 156.78 2.68 2.67 2.11 0 0 0 0 0 0

8 3 151.86 141.59 156.10 2.25 2.55 2.13 0 0 0 0 0 0

16 32 133.20 125.51 143.60 2.82 3.07 2.49 0 0 0 0 0 0

32 32 142.99 129.31 142.04 2.51 2.94 2.54 0 0 0 0 0 0

32 64 129.90 125.89 144.74 2.92 3.06 2.45 0 0 0 0 0 0

64 64 141.80 126.06 145.58 2.54 3.05 2.43 0 0 0 0 0 0

64 128 128.74 123.30 143.77 2.96 3.15 2.48 0 0 0 0 0 0



2 3 132.54 138.59 144.35 2.84 2.64 2.47 0 0 0 0 0 0

8 3 143.12 145.21 147.96 2.50 2.44 2.36 0 0 0 0 0 0

16 32 131.21 133.68 144.63 2.88 2.80 2.46 0 0 0 0 0 0

32 32 149.95 150.35 153.07 2.30 2.29 2.21 0 0 0 0 0 0

32 16 149.69 149.22 151.33 2.31 2.32 2.26 0 0 0 0 0 0

64 32 151.13 149.02 151.16 2.27 2.33 2.27 0 0 0 0 0 0

32 64 125.61 131.33 14.078 3.07 2.88 2.48 0 0 0 0 0 0



2 3 107.90 115.00 115.50 3.73 3.54 3.43 0 0 0 0 0 0

8 3 123.33 124.97 124.65 3.15 3.09 3.10 0 0 0 0 0 0

16 32 107.73 111.07 112.82 3.74 3.60 3.54 0 0 0 0 0 0

32 32 121.98 121.70 122.60 3.20 3.21 3.18 0 0 0 0 0 0

32 16 126.70 125.32 125.90 3.03 3.08 3.06 0 0 0 0 0 0

64 32 122.92 121.45 122.63 3.16 3.22 3.17 0 0 0 0 0 0

32 64 104.12 107.95 110.22 3.89 3.73 3.64 0 0 0 0 0 0





Table 4.6 „Lighthouse.jpg‟

In the above test we have recognized that the proposed system could provide effective encryption in comparison

with the existing algorithm. The table 4.1 to table 4.6 shows data shows pixel change for each layer for some of the

block sizes of “image name”. In addition the block size 4 shows maximum distortion between the cover and cipher

image. Furthermore, the attacker may employ the brute force attack that tries all possible combination to construct

the perfect master image.

V. CONCLUSION

It is evident from this investigation that in the presented work is a high level of encryption is achieved by

interchanging position of various blocks by the complex combination of different algorithms acting at individual

level without involving any complex calculation. On the hand Other various encryption algorithm namely RSA,

DES etc. are very well for encrypting textual data but as far as the image encryption is concerned it uses more

memory as well as take more time because of bulk image data.

Further it has two levels of encryption that could address both pay-per view applications or secured communication

simultaneously.

REFERENCES

[1] Information available on RGB model via www at http://en.wikipedia.org/wiki/RGB_color_model.

[2] RSA Security. http://www.rsasecurity.com/rsalabs/faq/3-2-6.html

[3] DES. http://csrc.nist.gov/publications/fips/fips46-3/fips46-3.pdf. The urlexplains the concept of the Data

Encryption Standard.

[4] W. Stallings, Cryptography and Network Security. Englewood Cliffs,

[5] S. S. Maniccam and N. G. Bourbakis,“Image and video encryption usingscan patterns,” Pattern

Recognition 37, pp. 725-737, 2004.NJ: Prentice Hall, 2003.

[6] Ankita P. Baheti, Lokesh Singh ,AsifUllah Khan; “A Comparative Literature Survey On Various Image

Encryption Standards” International Journal of Engineering Research & Technology (IJERT)Vol. 2 Issue 4,

April – 2013,ISSN: 2278-0181

[7] NehalKandele, ShrikantTiwari; “A New Combined Symmetric Key Cryptography CRDDBT Using –

Relative Displacement (RDC) and Dynamic Base Transformation (DBTC)” International Journal of

Engineering Research & Technology (IJERT),Vol. 2 Issue 10, October – 2013,ISSN: 2278-0181

[8] Ahmed Bashir Abugharsa, AbdSamad Bin HasanBasari and HamidaAlmangush; “A New Image

Encryption Approach using Block-Based on Shifted Algorithm” IJCSNS International Journal of Computer

Science and Network Security, VOL.11 No.12, December 2011,pp 123-130.

[9] A.Mitra, Y. V. SubbaRao and S. R. M. Prasanna; “A New Image Encryption Approach

usingCombinational Permutation Techniques”World Academy of Science, Engineering and Technology 14

2008,pp-919-923

[10] UmashankarPandey, Manish Manoria,Jainendra Jain; “A Novel Approach for Image Encryption by New M

Box Encryption Algorithm using Block based Transformation along with Shuffle Operation” International

Journal of Computer Applications (0975 – 8887) Volume 42– No.1, March 2012, pp-9-15


2 3 147.22 140.47 119.08 2.38 2.58 3.30 0 0 0 0 0 0

8 3 150.15 149.09 136.72 2.30 2.33 3.03 0 0 0 0 0 0

16 32 151.57 126.98 117.08 2.25 3.02 3.38 0 0 0 0 0 0

32 32 151.49 146.94 129.97 2.26 2.39 2.92 0 0 0 0 0 0

32 16 154.11 150.10 130.30 2.18 2.30 2.91 0 0 0 0 0 0

64 32 152.47 147.68 128.99 2.23 2.37 2.95 0 0 0 0 0 0

32 64 152.35 124.79 116.0 2.23 3.10 3.41 0 0 0 0 0 0



2 3 121.51 130.89 142.13 3.21 2.89 2.53 0 0 0 0 0 0

8 3 135.45 139.76 148.93 2.74 2.61 2.33 0 0 0 0 0 0

16 32 120.66 127.93 141.33 3.24 2.99 2.56 0 0 0 0 0 0

32 32 140.25 142.80 152.50 2.59 2.51 2.23 0 0 0 0 0 0

32 16 142.18 142.84 150.96 2.53 2.51 2.27 0 0 0 0 0 0

64 32 140.16 142.17 149.20 2.59 2.53 2.32 0 0 0 0 0 0

32 64 120.94 130.71 139.87 3.23 2.90 2.60 0 0 0 0 0 0




[11] G.A.Sathishkumar and K.BhoopathyBagan; “A Novel Image Encryption Algorithm Using Pixel Shuffling

and BASE 64 Encoding Based Chaotic Block Cipher (IMPSBEC)”WSEAS TRANSACTIONS on

COMPUTERS,ISSN: 1109-2750,Issue 6, Volume 10, June 2011,pp 169-178

[12] Pooja Mishra, BijuThankachan; “A Survey on Various Encryption and Key Selection

Techniques”International Journal of Engineering and Innovative Technology (IJEIT),Volume 2, Issue 7,

January 2013,pp 141-145.

[13] Quist-AphetsiKester; “ A Visual Cryptographic Encryption Technique for Securing Medical

Images”International Journal of Emerging Technology and Advanced Engineering, ISSN 2250-2459,

Volume 3, Issue 6, June (2013),pp 496-500.

[14] Mintu Philip; “An Enhanced Chaotic Image Encryption”,International Journal of Computer Science,

Engineering and Information Technology (IJCSEIT), Vol.1, No.5, December 2011,pp 77-83

[15] Manjunath Prasad and K.L.Sudha, “Chaos Image Encryption using Pixel shuffling ”,D.C. Wyld, al. (Eds):

CCSEA 2011, CS & IT 02, pp. 169–179, 2011

[16] HiralRathod, Mahendra Singh Sisodia, Sanjay Kumar Sharma, “Design and Implementation of Image

Encryption Algorithm by using Block Based Symmetric Transformation Algorithm (Hyper Image

Encryption Algorithm)”,International Journal of Computer Technology and Electronics Engineering

(IJCTEE),Volume 1, Issue 3,pp. 7-13

[17] AbhishekMisra, Ashutosh Gupta, DamodarRai, “Analysing the Parameters of Chaos Based Image

Encryption Schemes” World Applied Programming, Vol (1), No (5), December 2011. 294-299

[18] R. liu, X. tian “New algorithm for color image encryption using chaotic map and spatial bit level

permutation “Journal of Theoretical and Applied Information Technology 15 September 2012. Vol. 43

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