Veena [email protected] Abstract—Information security has become a vital part

Veena Venkitesh

1Department of
Computer Science and Engineering, Adi Shankara Institute of Engineering and
Technology

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Email: [email protected]

 

Divya D

1Department of
Computer Science and Engineering, Adi Shankara Institute of Engineering and
Technology

Email: [email protected]

Abstract—Information security has become a vital part in most
organizations. The main reason for this is that access to information and the
associated resources has become easier because of the developments in
distributed processing, for example the Internet and electronic commerce. The
result is that organizations need to ensure that their information is properly
protected and that they maintain a high level of information security. In many
cases, organizations demand some proof of adequate information security from
business partners before electronic commerce can commence.

In today’s information age,
information sharing and transfer has increased exponentially. The threat of an
intruder accessing secret information has been an ever existing concern for the
data communication experts. Cryptography and steganography are the most widely
used techniques to overcome this threat. This paper discusses a basic approach
to enhance data security.

Keywords-Cryptography; Security;
Encryption;

I. INTRODUCTION

In
the world today, there is a rapid increase in the number of internet users. A
recent statistics shows that there are 3.5 billion people who use internet.
Within a year, there has been a tremendous increase in the internet users to
over a billion. Due to the increase in the internet for commercial and
noncommercial purposes, there is an increased need for security of data that is
transferred or exchanged.

 

Therefore,
it is the necessary application of reliable data security techniques for data
exchange via internet media. Cryptography and Steganography are two of the most
commonly used to secure digital data. Cryptography is a technique for securing
data where the original data is randomized in such a way that it is difficult
to understand. Original data can only be opened by a specific person using predefined
custom keys.

II.VISUAL CRYPTOGRAPHY AND STEGANOGRAPHY

Visual
Cryptography is a special encryption technique to hide information in images in
such a way that it can be decrypted by the human vision if the correct key
image is used. The original information that is to be encrypted is known as
secret. Once the encryption is completed, ciphers are generated which is known
as shares. The part of secret in twisted form is known as share. To share the
secret among group of n participants is the fundamental idea behind visual cryptography.

 

The
secret is divided into n number of pieces, referred as shares, in order to
share the secret. After that, these shares are distributed among n
participants. Each participant provides his own share, to reveal the original
secret. There are many visual cryptographic schemes are available, but the
basic scheme is 2out of 2visual cryptography. In this scheme secret image is
divided in to exactly two shares, if both two shares are superimposed then
secret will be revealed. In (k, n) visual cryptographic scheme secret image is
divided into n shares; if k or more then k shares are superimposed then  secret will be decoded. The (n, n) visual
cryptographic scheme is extended version of (k, n) visual cryptographic scheme.
In (n, n) visual cryptographic scheme all n shares are require to decrypt
secret while revealing the secret. Figure 1 shows 2 out of 2 Visual
Cryptography shares.

                            Figure 1: 2 out of 2 VC scheme

Steganography is the technique of writing secret or
confidential messages in a way such that no one but only the intended receiver
knows of the existence of the information; this is in contradictory to
cryptography, where the existence of the message itself is not disguised, but
the content is obscured. Steganography clearly means covered or hidden writing
or information passed with secrecy. Usually, a steganographic message will be
shown to be something else: a picture, an article, or some other information –
the cover text. Steganography is always chosen over cryptography because the
messages do not attract attention to themselves but to messengers Figure 2 shows
a basic Steganography framework.

 

                       Figure 2: Steganography Framework

 

In an
unaltered Steganography framework, the mechanism for embedding the message is
unknown to Wendy and shared as a secret message between Alice and Bob.

 

III. RELATED WORK

Here we are combining both visual cryptography
and steganography technique for enhancing data security. The implementation of Steganography
in blend with visual cryptography is a powerful model and adds a lot of
challenges to identifying such hidden and encrypted data. Basically, a user
could have a secret image with the secret data which could be split up into a
range of encrypted shares. Finally when such encrypted shares are reassembled
or decrypted to restore the real image it is possible for one to have an
exposed image which yet consists of the secret data.

IV. PROPOSED TECHNIQUE

Algorithm for steganography:-

The
function used in this cryptosystem should have a bijective mapping i.e. the
function should have one-one and onto mapping. This indicates the inverse of
the function exists.

Hence the original information of
the image can be retrieved back during decryption without any error. The
function is given as:

 

 

 

Encryption &
Decryption:-

Step 1: Ask for the
image and the keys X1 and Y1 and the resizing factor “fac”.

Step 2: Generate the function g( ) which will contain the values
generated from a function in an array.

Step 3: Find the absolute value of the function g( ). Here U=GCD(X1,
Y1).

Step 4: Pass it through a low pass filter.

Step 5: Resize the image using bi-cubic interpolation and get the
RGB layer in a separate matrix with the factor “fac”.

Step 6: Multiply the pixel values with the absolute values
calculated.

Step 7: Flip the new formed Red matrix upside-down.

Step 8: Flip the new formed Green matrix left-side right.

Step 9: Rotate the Blue matrix by twice of the “fac”.

Step 10: Generate the image again save it in .bmp format. (The
image is saved in .bmp format because actual values of the pixel are retained
and the number of pixels is also the same which is in contrast with the other
compressed images like jpeg, gif, etc.)

Step 11: Send the image with the resizing factor to the receiver.

Decryption
is just the reverse process of encryption. The aim of decryption is to make the
encrypted information readable again (i.e. to make it unencrypted).

Step 1: Receive the image and ask for the key and resizing factor.

Step 2: Break the received image into Red Green and Blue
parts/layers.

Step 3: Flip the new formed Red matrix upside-down.

Step 4: Flip the new formed Green matrix left-side right.

Step 5: Rotate the Blue matrix by twice of the “fac”.

Step 6: Generate the function depending upon the keys. Here U=GCD(X1,
Y1).

Step 7: Find the absolute value of function and pass it through
low pass filter.

Step 8: Divide the pixel values of the received image with the
absolute value of the function.

Step 9: Form the image.

Step 10: Resize the image by multiplying its rows and column with
the “fac” using bi-cubic interpolation.

V. RESULTS

Here, we are analyzing the results of proposed and existing techniques
and we found that proposed technique can play important role in concerned area.
Table 1 shows the comparison between existing and proposed techniques.

 

Table 1: Comparison between existing and proposed techniques

Parameters

Existing Technique

Proposed
Technique

Security
 

Human Vision
 

Time
 

Confidentiality
 

Efficiency

Low
 
Predictable
 
Medium
 
Low
 
Medium

High
 
Unpredictable
 
Low
 
High
 
High

Durability against damage

Not Retrievable

Reading upto 30% damage

V. CONCLUSION

Steganography and visual cryptography have many similarities
and differences, and thus have various uses in the digital and real worlds.
Different algorithms for steganography and visual cryptography have different
advantages and power, as well as disadvantages and weaknesses. So we notice
that certain methods are easier to detect than others. But generally, the job
of forensic and security investigators is not easy. When steganography and
visual cryptography detection tools are used exclusively, it is almost
impossible for investigators to uncover hidden or encrypted data. On the
contrary, if these detection tools or softwares are used in connection with
other tools and parameters that reduce the search to a smaller data set, then
it makes the lives of investigators much easier and provides them a better
chance of detecting the suspicious data. It is always surprising to learn how
detectable a data is after applying visual cryptography with perfect restoration
to an image with secret data. Also, an interesting detection question is
whether we can reconstruct a set of ‘n’ shares into a meaningful image that is
different thanthe image used to create those shares by omitting some of the n
original shares and by including an additional share specifically constructed
for such purpose. Basically this is a question about the uniqueness of the
shares created by different visual cryptography algorithms.

 

When
Visual Cryptographyis used with Steganography it makes the task difficult to
decrypt the secret message. This makes the system a highly secure, durable and
efficient in information protection. Our future work is to provide the security
by using latest cryptographic algorithm and research for further improvements
to carry out so that we could come up with new ideas which will be beneficial
for the society.

 

VI. REFERENCES

1    https://www.ukessays.com/essays/computer-science/steganography-and-visual-cryptography-in-computer-forensics-computer-science-essay.php

2    https://www.sciencedirect.com/science/article/pii/S1877050915032445

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