International Journal of Engineering Trends and Technology (IJETT) – Volume 4 Issue 8- August 2013
Enhanced Cipher Image Generation Using Nibbles and Zigzag Patterns
1
M.srinivasarao, 2D.srinivasulu
M.tech student, st.ann'scollege of engineering&technology
2
assoc professor, st.ann'scollege of engineering&technology
1
Abstract: Today data protection is very
converting the known data format into
essential and main concern issue. As the
unknown data format. Nowadays, image
communication in now a days has been
encryption schemes have been increasingly
increasing rapidly through mobile phones,
developed to meet the requirements for
televisions and web there is need of providing
secure transmission over the communication
security to the data to be transmitted.
channels. However there are several image
Information exchange
encryption methods, each of them having
is must
in any
communication field like military, defense
their
applications. As the data to be transmitted
Classification
must be highly secured and confidential we
methods in to three major types: position
need to protect the data from the hackers. The
permutation, value transformation and visual
technique employed to provide the data
transformation. In this paper we do the
security is encryption. Here we employ an
encryption partially on the image which saves
effective fractional encryption method based
time of execution and complexity. We have
on SCAN patterns and selecting a pixel value
presented
of rearranged mapping image based on the
performs both lossless compression and
mapping function.
encryption of binary and gray-scale images.
Keywords: Encryption, Decryption, SCAN
The compression and encryption schemes are
language, DCT, Image processing
based on SCAN patterns generated by the
Introduction: In the digital world today, the
SCAN methodology. The SCAN is a formal
protection of digital images becomes more
language-based
and
the
accessing methodology which can efficiently
communications of digital products over
specify and generate a wide range of
networks occur more and more recurrently.
scanning paths or space filling curves.
Let us consider transferring of an image
Principles of encryption: In a simplest form,
through the network which needs more
encryption is to convert the data in some
attention while delivering the data. We make
unreadable form. This helps in protecting the
sure that every thing is secured in the
privacy while sending the data from sender to
transmission. Encryption is the process of
receiver. Cryptography has become one of
more
significant,
ISSN: 2231-5381
since
own
a
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strength
of
the
new
and
weakness.
image
encryption
methodology
two-dimensional
which
spatial
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International Journal of Engineering Trends and Technology (IJETT) – Volume 4 Issue 8- August 2013
the main tools for privacy, trust, access
for encryption and decryption. AES is a
control,
symmetric key algorithm which uses same
electronic
payments,
corporate
security, and countless other fields. Strong
key for both encryption and decryption.
encryption is the kind of encryption that can
Block diagram
decryption:
be used to protect information of real value
against organized criminals, multinational
corporations, and major governments. In
Original
data
of
encryption
and
Key
encryption terminology, the message is called
clear text. Coding the contents of the message
in such a way that hides its contents from
outsiders is called encryption. The encrypted
message
is
called
the
cipher
Encrypted
data
Key
text.
Cryptography is the art or science of keeping
Original
data
messages secret. Cryptanalysis is the art of
breaking ciphers, i.e. retrieving the plaintext
without knowing the proper key. There are
The above block diagram shows the basic
two
encryption
building blocks of encryption and decryption
asymmetric
which converts the user understandable data
algorithms. The symmetric key algorithms
into unknown format and vice versa with the
uses same key for both encryption and
help of encryption and decryption algorithms.
classes
algorithms,
of
key-based
symmetric
and
decryption where asymmetric algorithms uses
different keys at encryption and decryption.
Advantages of encryption:
Strong cryptographic algorithms are designed
Individuality Theft avoidance.
to be executed by computers or specialized
Secure
hardware devices. In most applications,
cryptography is done in computer software.
Decommissioning
of
Computer.
Unauthorized entrée Protection.
Here we discuss about different algorithms in
Designing of system: The SCAN is an
encryption. Data Encryption Standard this is
official language-based two dimensional
a cipher that operates on 64-bit blocks of
spatial accessing methodology which can
data, using a 56-bit key. The algorithm is best
symbolize and produce a large number of
suited to implementation in hardware. A 'hash
wide varieties of scanning paths. This
algorithm' is used for computing a condensed
method converts a 2D image into a 1D list,
representation of a fixed length message/file.
and employs a SCAN language to describe
RSA is the algorithm that uses different keys
the converted result. In this language, there
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International Journal of Engineering Trends and Technology (IJETT) – Volume 4 Issue 8- August 2013
are several SCAN letters. Each SCAN
approaches.
Furthermore,
many
image
letter represents one kind of scan array.
encryption
algorithms
have
been
Different kinds of combinations of SCAN
implemented in software, due to the resulting
letters may produce different kinds of
flexibility and the algorithm complexity. This
furtive images. The SCAN is a family of
means that most of these algorithms are good
formal languages such as Simple SCAN,
for non real- time image encryption but not
Extended SCAN, and Generalized SCAN,
for compressed video encryption. Very few
each of which can represent and generate a
extensively used image encryption algorithms
specific set of scanning paths. After
have been implemented in hardware, and
determining the combination of SCAN
generally
letters, the scheme then generates a SCAN
compression. On the other hand, many block
string. This string defines the scan order of
cipher, which are used for encrypting text
the original image. Scanning of a two
data, have been used to encrypt images. In
dimensional array is an order in which each
reality, SCAN is a class of formal languages,
element of the array is accessed exactly
which can be applied to compression,
once. Following by basic scan patterns and
encryption, data hiding, or combinations
partition patterns to produce concept, we
thereof. The SCAN family of general
use a random code generating produce the
languages includes several versions such as
SCAN word and to define encryption key.
Simple
The SCAN word contain scan and partition
Generalized SCAN, each of which can
patterns.
represent and produce a specific set of
Various algorithms have been proposed to
scanning paths. Each SCAN language is
encrypt images. Most image encryption
defined by a grammar and each language has
algorithms
position
a set of basic scan patterns, a set of
permutations with or without confusion
transformations, and a set of rules to create
functions in which the pixel values are
simple scan patterns, which in turn are used
jumbled to different positions on the 2D
to obtain complex scan patterns. A scanning
array. The other algorithms are based on
of a two dimensional array is an order in
confusion transformations where disordered
which each part of the array is accessed
binary sequences are generated for the
exactly once. The SCAN is a formal
reorganization of the image pixels, on tree
language-based
structures
accessing methodology which can represent
are
where
based
the
on
pixel
values
are
converted by using certain functions, or on
in
SCAN,
conjunction
Extended
two
with
image
SCAN,
dimensional
and
spatial
and produce wide variants of scanning paths.
other methods like the quantization based
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International Journal of Engineering Trends and Technology (IJETT) – Volume 4 Issue 8- August 2013
DCT:
DCTs
many
intermediate values of the computation we
applications in science and engineering, from
should allow two or more parties to interact.
lossy compression of audio and images (e.g.
However, since we would keep the DCT as
JPEG) to spectral methods for the numerical
simple as possible, it is preferable to avoid
solution of partial differential equations. A
the use of interactive protocols. A final
discrete cosine transform (DCT) expresses a
setback
finite sequence of data points in terms of a
separately increases the size of the encrypted
sum of cosine functions oscillating at
image and affects the complexity.
different frequencies. In particular, a DCT is
Image compression: Digital images are very
a Fourier-related transform analogous to the
large in size and occupy more bandwidth
discrete Fourier transform (DFT), except
while uploading to the web, to combat this
using only real numbers. The most common
problem user has to reduce the size of the
variant of discrete cosine transform is the
digital image with out degrading its quality.
type-II DCT, which is often called simply
Image compression plays a key role in image
"the DCT", its inverse, the type-III DCT, is
processing where the channel capacity is the
correspondingly often called simply "the
main concern. Image compression is the
inverse DCT" or "the IDCT". The DCT, is
novel method to reduce the size occupied by
widely used in signal and image processing,
the image when we are transmitting through
especially
compression,
the band limited channel. The main motto of
because it has a strong "energy compaction"
the image compression is to reduce the
property.
redundancy and irrelevant data in the
The DCT can be computed on the encrypted
transmitted image.
pixel
the
Image compression can be done in two ways
homomorphism properties and the fact that
lossy and lossless. In lossy compression
the DCT coefficients are public. However,
technique user should compromise in the data
this needs several issues to be satisfied. The
quality and we may loss some useful
foremost thing is that we should represent the
information, lossy methods are especially
pixel values, the DCT coefficients, and the
suitable
transformed values in the domain of the
photographs in applications where minor
cryptosystem, i.e., as integers on a finite
(sometimes imperceptible) loss of fidelity is
field/ring.
acceptable.
for
values
are
significant
lossy
by
data
relying
to
on
One more difficulty is that
is
that
for
encrypting
natural
In
images
case
the
such
as
lossless
compression
truncated by relying on homomorphism
information with out any compromises in the
computations only. In general, for scaling the
quality of the data. With the implementations
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get
of
pixel
encrypted values can not be scaled or
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we
the
each
maximum
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International Journal of Engineering Trends and Technology (IJETT) – Volume 4 Issue 8- August 2013
of compression algorithms we can send more

data through the same channel at different
time instants without any disturbance among
image.

the data packets. We can employ region of
interest coding method to encode and
Decrease color nuances within the
Decrease the color resolution with
respect to the prevailing light intensity

compress any particular part of the image
Remove small, invisible parts of the
picture
effectively. As we send more data packets
through the channel it increases the bit rate of
the channel. Bit rate tells how many are
transmitted through the channel in the given
time period. It is the ration of bits per second
Basically there are two standards in image
compression JPEG and MPEG. JPEG deals
with the still images while MPEG is
associated to the video sequences. Generally
use
DCT
method
followed
by
quantization to reduce the size of the image.
Compression ratio varies from technique to
technique. In the ordinary JPEG algorithm
the image is divided into 8×8 blocks, these
blocks are converted from the spatial to the
frequency domain by the Discrete Cosine
Transform
(DCT).
Then,
each
DCT
coefficient is divided by its equivalent
constant in a standard quantization table and
rounded down to the nearest integer. After
this step, the DCT quantized coefficients are
scanned in a predefined zigzag order to be
used
in
We can upload the images very speedily
into the web.
They use less space in web hosting.
They take very less time to host.
(bits/sec).
we
Advantages:
the
final
compression.
Image data reduction:
step,
the
lossless
Sharing
of
files
can
be
easy with
compression.
Image compression does not decrease the
physical size of an image but compresses the
data that makes up the image into a smaller
size.
DCT process on image:
Take the input image and resize it.
Segment the image into 8x8 blocks.
Reduce the higher intensity values from the
image.
Consider a quantized matrix with quantized
values.
Divide the image with the quantized matrix.
Procedure of encryption:
We perform the partial encryption of the
image as follows.
Step 1: select an input image to be
transmitted and take a combine value.
Combined value defines the level of
encryption.
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International Journal of Engineering Trends and Technology (IJETT) – Volume 4 Issue 8- August 2013
Step 2: select a mapping image and rotate it
by some angle.
Step 3: perform encoding of an image which
consists the following steps.
Segment the image with DCT and reduce
the higher values in the image.
Generate the nibbles and zigzag pattern
from the image.
Combine all these to get the transformed
form of the image.
Step 4: to retrieve the image we do the
reverse operations such as IDCT and inverse
zigzag operations. Finally the resultant image
Transmit the
image
is stored as restored image.
The following diagram shows the procedure
to generate a secret image by using DCT and
SCAN
patterns.
We
generate
partially
encrypted image through this process.
Flow diagram:
Results:
Select the input
image
Select mapping
image & rotate
with an angle
Reduce the
higher values
from the image
Apply DCT
with quantized
matrix
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Generate
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International Journal of Engineering Trends and Technology (IJETT) – Volume 4 Issue 8- August 2013
data. We can employ the encryption methods
in
cellular
broadcasting,
technology,
military
applications.
We
can
television
and
defense
employ
encryption methods where the
these
channel
capacity is limited.
Conclusion: In this communication, new
ways of image encryption scheme have been
proposed which utilizes SCAN patterns. This
paper has presented a concept of combination
of nibble value of a pixel is used as a
mapping function. This Encryption uses only
integer arithmetic and it can be easily
implemented in the hardware. we conclude
with the remark that the method is expected
to be useful for real time image encryption
and transmission applications.
References:
[1] Data Privacy and Security: Encryption
and Information Hiding By David Salomon.
[2]Computer security and the data encryption
standard ... Volume 500, Issues 1-6 By
Advantages:

We can keep our data more securely from
United States. National Bureau of Standards.
the unauthorized persons.

The system which we employ is easy to
[3]Multimedia
Content
Encryption:
Techniques and Applications By Shiguo
use.

United States Civil Service Commission,
Generation of key (patterns) is easy as we
are generating from image it self.
The partial encryption saves the time and
Lian.
[4]Multimedia Encryption and Authentication
Techniques
and
Applications By
Borko
Furht, Darko Kirovski.
complexity of the process.
Applications: As the technology is growing
rapidly we must provide the security for the
[5]Applied Cryptography for Cyber Security
and Defense: Information Encryption by Li
yang.
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International Journal of Engineering Trends and Technology (IJETT) – Volume 4 Issue 8- August 2013
[6]Computational Intelligence in Information
Assurance and Security edited by Nadia
Nedjah, Ajith Abraham, Luiza De Macedo
Mourelle.
[7]http://www.computer.org/csdl/proceedings
/iv/2004/2177/00/21770217-abs.html.
[8]http://www.docstoc.http://www.researchm
anuscripts.com/isociety2012/46.pdf
[9]http://www.docstoc.com/docs/50227726/S
electiveImageEncryptionUsing-DCT-withStream-Cipher.
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