An Advance Approach of Image Encryption using AES, Genetic Algorithm and RSA Algorithm

International Journal of Engineering and Applied Computer Science (IJEACS)
Volume: 02, Issue: 08, ISBN: 978-0-9957075-9-7, August 2017
DOI:10.24032/ijeacs/0208/01 www.ijeacs.com 245
An Advance Approach of Image Encryption using
AES, Genetic Algorithm and RSA Algorithm
Avinash Ray
Department of Electrical &
Electronics Engineering
NITTTR, Bhopal, India
Anjali Potnis
Prashant Dwivedy
Shahbaz Soofi
Abstract— In current scenario the entire world is moving towards
digital communication for fast and better communication. But in
this a problem rises with security i.e. when we have to store
information (either data or image) at any casual location or
transmit information through internet. As internet is an open
transmission medium, security of data becomes very important.
To defend our information from piracy or from hacking we use a
technique and i.e. known as Encryption Technique. In this paper,
we use image as information and use an advance approach of
well-known encryption techniques like AES, Genetic Algorithm,
and RSA algorithm to encrypt it and keep our information safe
from hackers or intruders making it highly difficult and time
consuming to decipher the image without using the key.
Keywords-AES, Communication, Decrptyion, Encryption,
Genetic, Information, Open Transmission Medium, RSA, Security.
I. INTRODUCTION
In recent scenario information or data transmission is done
through electronic means or we can say with the help of
internet. Internet is an open transmission medium, so there is
chance of data hacking or data piracy while it is being
transmitted. Another problem arises with the data storage. That
is sometimes we save some crucial messages in such devices
which are operated by many people. So, at that time there is
chance of Piracy of data. To stop these all piracy and hacking a
technique is used to protect our information and is known as
Encryption Technique. Encryption is a technique which uses
finite set of instructions called an algorithm [1] to convert
original message known as plain text, into encrypted form (or
coded form) known as cipher text. Cryptographic algorithm
normally requires a set of characters called as „key‟ to encrypt
or decrypt data. With the help of key and algorithm we can
encrypt or decrypt plain text into cipher text and then cipher
text to plain text.
Encryption is of two types. One is Asymmetric Algorithm
which is also called Asymmetric cryptography. It is usually
implemented by the use of one-way functions. In mathematical
terms, these are functions that are easy to compute in one
direction but very difficult to compute in reverse manner. This
is what allows you to publish your public key, which is derived
from your private key. A common one-way function used
today is factoring large prime numbers. It is easy to multiply
two prime numbers together and get a product. However, to
find out the factors there are numerous possibilities, and it is
one of the great mathematical difficulties e.g. RSA Algorithm
And second one is Symmetric Algorithm which is also
called as called symmetric cryptography or shared secret
encryption [2]. This form of encryption uses a secret key,
called the shared secret, to mix up the data into impenetrable
twaddle. The person on the receiver end needs the shared secret
(key) to unlock the message. It is called symmetric
cryptography because the same key is used on both ends (i.e. at
the sender end and at receiver end) for both encryption and
decryption e.g. Genetic Algorithm.
In this paper, we take an image as input and perform
different encryption technique over it. Here we encrypt a single
image with three different encryption techniques [3] one by one
in which some techniques are of symmetric algorithm and
some are of asymmetric algorithm (like Genetic, AES, and
RSA). Here all encryption techniques are used one by one that
is output of one encryption technique is converted in input, of
another encryption technique, or it is better to say all
encryption technique is used in cascade manner. After
execution of all encryption technique over input image, we get
a highly encrypted image which is very difficult to decrypt
without the authorization of its generator because of its dual
nature i.e. symmetric and asymmetric encryption technique.
Here to decrypt the image users need „key‟, because of secret
key algorithm, and the key must be provided by generator only.
II. METHODOLOGY
Here a list of the several encryption techniques are given
which are used in this hybrid model of image encryption
technique.
A. AES Algorithm
It is also known as Rijndael [2]. The AES algorithm [7]
was developed by Vincent Rijmen and Joan Daemen. In
October 2000 NIST acknowledged that AES algorithm is one
of best algorithm in security, performance, efficiency, ability

Avinash Ray et al. International Journal of Engineering and Applied Computer Science (IJEACS)
of implementation, and also flexibility. The AES is a
symmetric key algorithm, in this both sender and receiver
uses identical key to encrypt data into cipher and then to
decrypt cipher into original data. In this algorithm, it has a
fixed block length of 128 bits, while the length of key size
can be of 128, 192, or 256 bits. It [3] is an iterative algorithm.
It is composed of 4 basic operational blocks. For complete
encryption iteration is performed up to N times. The total
number of iteration i.e. N can be 10, 12, and 14 based on key
length i.e. 128, 192, and 256 respectively.
1) Encryption: In the key expansion round keys are
derived from the cipher key using Rijndael's key schedule.
AES requires a separate 128-bit round key block for each
round plus one more.
a) Initial Round: Add Round Key, each byte of the
state is combined with a block of the round key using
bitwise XOR.
b) Iterative Round’s: In the iterative round four
operations are performed which include sub bytes operation
which is a non-linear substitution step where each byte is
replaced with another according to a lookup table. Shift
rows is a transposition step where the last three rows of the
state are shifted cyclically a certain number of steps. Mix
columns is a mixing operation which operates on the
columns of the state, combining the four bytes in each
column. Finally, addition of round key is performed.
c) Final Round: In the final round all the above
operations are repeated except in the final round mix
columns is not performed.
2) Decryption: Inverse sub bytes, inverse shift rows
and inverse mix columns are used in reverse order instead of
sub bytes, shift rows, and mix columns. The key expansion
remains the same.
B. Genetic Algorithm
Genetic Algorithm (GA) is a penetrating technique used
in computer science to find out approximate solution to
optimization problems. Genetic Algorithm [8] (GA) is first
proposed by John Holland and his contemporaries at the
University of Michigan in 1975. Genetic Algorithm is a
particular class of evolutionary algorithm that used
techniques inspired from human evolution or evolutionary
biology like inheritance, mutation, natural selection and
recombination (also called crossover).
B. 1) Encryption: Take an image as input. Calculate its
Height (H) and Width (W) of the input image [9]. Find (H
mod 8) and (W mod 8), if they are equal to zero then go to
next step
H = H + (8 - (H mod 8)) (3)
W = W + (8 - (W mod 8)) (4)
Divide input image in two blocks, each block size is of
(8x8). Perform crossover operation. Perform mutation
operation get an encrypted block. Repeat last two steps for
each block to get an encrypted image.
2) Decryption: Take encrypted image as input. Go to
encrypted block. Perform mutation operation followed by
crossover operation to get decrypted block [10]. Repeat last
two steps for each block to get decrypted image.
C. RSA Algorithm
RSA is an algorithm developed in 1977 by Ron Rivest,
Adi Shamir, and Leonard Adleman [4]. In such a
cryptosystem, the encryption key is a public one and the
decryption key which is different from the encryption key is
kept private. As two different keys are being used in
encryption and decryption the RSA algorithm is also called as
an asymmetric cryptographic algorithm [5].
The RSA algorithm consists of three major steps in
encryption and decryption. The steps are as following
1) Key Generation: The RSA involves a public key and
a private key. Of these two keys the public key is used for
encrypting messages and can be known to everyone. The
messages encrypted with the public key are decrypted using
the private key. The process for key generation is as follows.
First choose two distinct prime numbers p and q and then
compute n = p x q where n is the modulus for the public key
and the private keys. Next compute φ (n) = (p − 1)(q − 1).
Choose an integer e such that 1 < e < φ (n) and GCD (e, φ(n))
= 1. The pair (n, e) is the public key. The private key is a
unique integer d obtained by solving the equation d.e ≡ 1
(mod φ(n)).
2) Encryption: The RSA algorithm [6] is used here for
encrypting an image. So the message text (m) is in the form
of pixels lying in the range 0 to 255. The pixels are stored
and operated upon in an array format. The text is encrypted
using the public key (n, e) from the equation
C=Me
mod (n) (1)
3) Decryption: The text is decrypted using the private
key (n, d) from the
M=Cd
mod (n) (2)
The decrypted pixels are obtained in the array format and
subsequently the decrypted image.
III. SIMULATION
The encryption is performed on two images one Lena.bmp
shown in figure 1 and other Mandrill.bmp shown in figure 2
both of size 512×512

Figure 1. Test Image Lena
Figure 2. Test Image Mandrill
In the hybrid model, the encryption is done by
combining the encryption techniques listed above in the
order shown in figure 3 where the output of each technique is
the input of the next encryption algorithm.
Figure 3. Flowchart for Hybrid Image Encryption
For decryption, the same techniques are applied in the
reverse order shown in figure 4.
Figure 4. Flowchart for Hybrid Image Decryption
Figure 5. Test Image Lena Encryption. a) Original Image b) Genetic
encryption c) AES encryption h) RSA encryption final image.
Figure 6. Test image Lena Decryption. a) RSA decryption b) AES
decryption c) Genetic decryption d) original image.

Figure 7. Test Image Mandrill Encryption. a) Original Image b) Genetic
encryption c) AES encryption d) RSA encryption final image.
Figure 8. Test image Mandrill Decryption. a) RSA decryption b) AES
decryption c) genetic decryption d) original image.
Figure 5 and 6 show the step by step encryption and
decryption of the test image Lena. Figure 7 and 8 show the
step by step encryption and decryption of the test image
Mandrill.
IV. MEASUREMENT PARAMETERS
To be able to tell how suitable the hybrid encryption model
is the following quality measurement parameters are employed
once between original image [10] and encrypted image and
once between original image and decrypted image.
• Mean Square Error (MSE)
• Peak signal to Noise Ratio (PSNR)
• Normalized Absolute Error (NAE)
• Normalized cross correlation (NCC)
• Average difference (AD)
• Structural content (SC)
• Maximum difference (MD)
Table 1 shows the measurement parameters employed
between the test image Lena and the encrypted Image [11]
and between the original image and its decrypted image.
TABLE I. QUALITY MEASURMENT PARAMETERS FOR
TESTIMAGE 1.
Measuremen t
Parameters
Comparison
between Original
Image Lena and
Encrypted Image
Comparison
between
Original Image
Lena and
Decrypted
ImageMSE 253.80 5.5098
AD 108.5366 1.5029
MD 243 5
NAE 0.8749 0.0121
NK 1 1
SC 1.44 1
PSNR 24.08 40.7195
Table 2 shows the measurement parameters employed
between the test image Mandrill and the encrypted Image and
between the original image and its decrypted image.
TABLE II. QUALITY MEASURMENT PARAMETERS FOR
TESTIMAGE 2
Measuremen
t Parameters
Comparison between
Original Image Lena
and Encrypted
Image
Comparison between
Original Image Lena
and Decrypted Image
MSE 245.67
.
5.5150
AD 93.06 1.5023
MD 238 5
NAE 0.8584 0.0139
NK 1 1
SC 1.4266 1.0004
PSNR 24.2271 40.7154
V. CONCLUSION
This paper presents a new image encryption method based
on a hybrid model of encryption using various encryption
techniques. Experimental results show that our model yields
high random cipher image measured by various quality
measurement parameters such as MSE, AD, MD and PSNR
thus making it difficult to recover the original image without
the key.

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© 2017 by the author(s); licensee Empirical Research Press Ltd. United Kingdom. This is an open access article
distributed under the terms and conditions of the Creative Commons by Attribution (CC-BY) license.
(http://creativecommons.org/licenses/by/4.0/).

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