Implementation of integrating Text based Watermarking
with Pseudo-Random Number Generator(PRNG) for
Cryptography Application
Chee Hon Lew1, Chaw Seng Woo2, Liang Shing Ng3
Faculty of Computer Science and Information Technology
University of Malaya, Malaysia
Email: Cheehon2006@siswa.um.edu.my1, cswoo@um.edu.my2, lsng@um.edu.my3
Abstract—In this paper, we focus on text based watermarking
techniques
based
on
Pseudo-Random
Number
Generator(PRNG)for Cryptography application. We survey
related work in digital watermarking, cryptography and design
methodology, then implemented text based watermarking
method (embedded and extract/detection of watermarks). We
show our implementation result based on text based digital
watermarking combined with cryptographic techniques. This
paper is intended to provide a reference finding for newcomer's
security designer and to promote more activities in these
security issues.
I.. INTRODUCTION
Cryptographic applications heavily rely on pseudorandom number generators(PRNG)to generate secrets key
such as session keys, passwords, and key pairs. They also
require random numbers that are public such as salts.
Random numbers are generated that they are unpredictable
to an attacker. As well, randomness is collected from real
random data to seed a PRNG, and once seeded, PRNGs
produce a long bit sequence of random numbers.
Unfortunately, cryptography can protect content in transit,
but once decrypted, the content has no further protection.
Therefore, digital watermarking has the potential to fulfill
this need,because it embeds information into the host data
or constructed binary pattern, where it is very difficult to be
removed during normal usage. In this paper, for the
convenience of the further research in this field, we present
the text based watermarking techniques combined with
Pseudo-Random
Number
Generator(PRNG)for
Cryptography application. We introduce in this article a
review of some of the keywords that used in current
literature and attempt have clear distinction of them.
Digital Watermarking(data-hiding) is the process of
embedding data into a multimedia element such as an image,
audio or video and text[1]. We can also define a watermark
as the digital data embedded in multimedia objects such that
the watermark can be detected or extracted at later times in
order to make an assertion about the object. The main
purpose of digital watermarking is to embed information
imperceptibly and robustly in the host data. Typically the
watermark contains information about the origin, ownership,
destination, copy control, transaction etc.[2]. In general, a
digital watermark is a code that is embedded inside an
image. It acts as a digital signature, giving the image a sense
of ownership or authenticity[2]. Unlike conventional
cryptographic techniques, it remains present within the data
even after the decryption process[2].
Pseudo-Random Number Generator(PRNG) is a
cryptographic algorithm used to generate numbers that must
appear strong(pseudo) random that cannot be guessed by an
attacker[3]. Random numbers are typically used to generate
session keys, and their quality is critical for the quality of the
resulting systems. Perfect randomness is a scarce resource,
currently pseudo random generators for all cryptographic
applications it is sufficient to use pseudo random bits
generator(PRB). A good
random number generation
improves the cryptographic security[4]. Pseudo-random
numbers is an important roles in many fields such as
statistical simulation systems, secret communication systems,
modern cryptography systems, any scientific area
incorporating Monte Carlo methods and so on.
Cryptography is the study of secret writing.[5] It is
the study of methods of sending messages in distinct form so
that only the intended recipients can remove the disguise and
read the message. A cipher is secret writing that means
plaintext is transformed into Ciphertext[5]. This process is
called encryption of the plaintext into ciphertext. More
generally, it is about constructing and analyzing protocols
that overcome the influence of adversaries[6] and which are
related to various aspects in information security such as data
confidentiality, data integrity, authentication, and nonrepudiation.[7]. Modern cryptography intersects the
disciplines of mathematics, computer science, and electrical
engineering. Applications of cryptography include ATM
cards, computer passwords, and electronic commerce,
military security and etc.
Most of the research work that has been done in this field
looks at increasing the output speed in computing the
cryptographic results in on TRNG platform[8]. As we read
another research related work in Research and Implementation
of RSA Algorithm in Java[9]and Text Watermarking Using
Combined Image-plus-Text Watermark[10,11], These two
papers discusses two separate independent studies on RSA
algorithm in Java and text watermarking using combined
image based watermarking. However, due to the lack of
research studies regarding to text-based digital watermarking
techniques based on PRNG for Cryptography application.
Therefore, we need to do this
experimental research on design and implementation of
text based watermarking combined with cryptographic
techniques. There are a few advantages of combining
watermarking with PRNG techniques:
 Good
security for combined these
two Watermarking with PRNG due to complex
algorithms.
 It makes a hacker hard to predict it public key due
to the combination RSA algorithms and
Watermarking algorithms.
 It can protect user and software developer for
authentication and data.
This paper is organized as follows: Section II describes our
research methodology and contributions. Section III
describes proposed model and implementation of Text
based Digital Watermarking Techniques embedded in
Pseudo-Random Number Generator (PRNG) algorithms
for Cryptography applications. Section IV shows our
experimental work and results. Finally, section V, we
provide our conclusion.
II. RESEARCH METHODOLOGY
III. PROPOSED MODEL
Figure 5. The Proposed model of Text based Digital Watermarking algorithms
embedded in Pseudo-Random Number Generator (PRNG) algorithms for
Cryptography applications.
generate
PRNG bit output combined with Text based Digital Watermarking Algorithm
Input
Message data
Seed
Encryption Algorithm
Reseed
Watermarking
Embedding process
Pool
Cover file
Stego Object
Watermarking
Extraction Process
End
Collect
Begin
No
Decryption algorithm
unpredictable inputs
The purpose of this research is to implement a text based
digital watermarking that combined with Pseudo-Random
Number Generator(PRNG). Thus, it will enable security
designers to address digital content protection privacy
concerns more efficiently. Developing a digital PRNG
composed of standard Cryptography design tools is
important because:

It alleviates the need for embedding a text based
digital watermarking design.

The PRNG can be incorporated with other digital
cryptographic components.

No external components are required for a text
based digital watermarking implementations.
To our knowledge, this research article makes the
following two sides contributions:
My contribution work does in Cryptography area as below:
 A better understanding of Pseudo Random number
primitives will make it easier to design and use
PRNGs securely.
 The Modification and improvement of PRNG based
on Open source RSA Algorithms.
My contribution work does in Watermarking area as
below:
 Better understanding concepts and methods of text
based watermarking combined with PRNG for
Cryptography application.
 The modification and improvement of text based
Watermarking based on Open source Watermarking
Algorithms.
 It makes a hacker hard to predict it public key due
to combination open source RSA algorithms and
watermarking algorithms.
Yes
Erase hidden
data
Output
Message data
Our implementation model is as shown in Figure 5.
The above left part is generalized PRNG with periodic
reseeding. PRNG with periodic reseeding that depicts a
possible architecture for implementing catastrophic reseeding.
The part of the internal state that is used to generate outputs
should be separate from the entropy pool. The generation state
should be changed only when enough entropy has been
collected to resist iterative guessing attacks, according to a
conservative estimate.
The above right part is proposed implementation model of
Text based Digital Watermarking Techniques. Although our
primary emphasis is on evolution of new Text-based Digital
Watermarking Technique but we are also aiming towards
providing a blended solution comprising of Encryption and
Text based Digital Watermarking dully added by PRNG
algorithm before encryption. To focus more on the subject and
proposing a closest possible feasible secure digital content
solution, The combination of hidden data-plus cover (known as
stego object) that holds the hidden information upon
watermarking extraction process. No message data can be
erased upon done RSA decryption algorithms. We shall be
using Pseudo-Random Number Generator (PRNG) algorithms
for embedding digital text based watermarking algorithms.
IV. RESULTS AND DISCUSSIONS
The following sequence of steps identifies RSA Key
Generator adopted in this work.
1. Define the problems.
2. An
algorithm
1:
Multiple-precision
library(BigInt.js) is a suite of routines for
performing multiple-precision arithmetic in
JavaScript.
3. An
algorithm
2:
Modular
reduction
library(Barrett.js) is a class for performing
Barrett modular reduction computations in
JavaScript.
4. An algorithm 3: RSA library(RSA.js) is a suite
of routines for performing RSA public-key
computations in JavaScript. It links algorithm 1
and algorithm 2 into algorithm 3 experimental
testing for plaintext, ciphertext, verification and
message keys.
5. The RSA key generator application is written in
Delphi 7, which is Object Pascal. This includes a
re-implementation of the multiple-precision library
and the Miller-Rabin test for primality. Keys are
generated using Algorithm 8.1 from the Handbook
of Applied Cryptography[12]-[13].
The following is procedures for compiling and testing RSA
Key Generator.
1.
Before the testing “RSA Key generator testing
file”,
make sure all files(BigInt.js,Barrett.js,
RSA.js)
including in the same directory.
2.
Open “RSA-testing” file by using Internet
Explorer
browser(such as Microsoft IE9, Google Chrome,
Firefox).
3.
You should be testing this file as below:
4.
5.
Use Borland Delphi 8 edition for compiling RSA Key
generator souce code. Run and compile all source code
files(Main.pas, BigMath.pas, RSA.pas)before it can
execute RSAkeygenerator(main program).
After run “RSAKeyGenerator” execution file, you
should testing this file as below:
Figure 7. RSA Key Generator Testing for generating new RSA key
6.
In order to secure RSA Key Generator Testing(figure
6), editing this source code by using Notepad or HTML
editor. Add the following JavaScript lines as below:
setMaxDigits;
// Put this statement in your code to create a new RSA key
with these parameters
key = new RSAKeyPair(
"3",
"18e78c00696284b3923a6d7401aee5b",
"255b52009e13c7108d7b57f0a764527"
);
7.
Repeat testing “RSA Key generator testing file”.
Done it.
This above implementation of the RSA key generator in
PRNG’s application. On the other hand, according to “A novel
dynamic model of pseudo random number generator”[20],in
his paper chaotic map equation.(refer to [20]) is used to design
a new PRNG algorithm.
12
x
(
x
,
α
)
=
t
a
n
(
N
a
r
c
t
a
n
x
) [14]
n
n
+
1
2
α
Our future research can extend the above further studies for
advance mathematics in chaotic functions theory and an
improved watermarking method based on double random
phase encoding technique[16] .
Furthermore, according to “Robust Hash Functions for
Digital Watermarking”[15], in his paper explained generates
the digital watermark from a pseudo-random Gaussian
sequence. The PRNG then generates a pseudo-random
sequence ξ(i) of a desired length (determined by the particular
watermarking technique)
Figure 6. The user interface of RSA Key Generator Testing
(
i
)


P
R
N
G
(
K

B

i

b

b

.
.
.

b

(
i
)

(
i
) [15]
1

(
i
)
q
2
In the expression above the symbol  denotes
concatenation. The final Gaussian sequence η  N(0,1)
is obtained by summing up ξ(i) for all i and normalizing:
()
i

3 

1
N i
N
[15]
Our future research can extend the above further studies
for double hash function for text based digital
watermarking.
Figure 8. Digital watermarking tool
V. FURTHER MODIFICATION AND
IMPROVEMENT
A. The modification and improvement of PRNG based
on an open source RSA algorithms
i) On RSA key Generator Testing source code file, we
edited a new RSA key pair statement. Due to perform
RSA Key Generator Testing, it generating new RSA
public key and private key. It always keep changing a
new RSA public key and private key after done
repeatedly RSA Key Generator Testing.
ii) Due to speed performance constraint, modified
maximum to 2048-bits RSA key(Common Cipher
strength 128-bit keys). So it can faster speed of
encryption and accuracy performance.
iii)
Due to RSA based PRNG encryption and
decryption, PRNG random bit sequence made its
strengthen the security of protecting data.
B. The Modification and improvement of text based
watermarking based on an open source Watermarking
algorithms
i)Semantic techniques is used for text based
watermarking
techniques.
The
semantic
watermarking schemes focus on using the semantic
structure of text to embed the watermark, so faster
speed and accuracy embedded the text contents.
ii)We edited open source watermarking algorithms, we
add up RSA based PRNG algorithms embedded with
text based watermarking algorithms. Nobody knows
it combined PRNG random bit sequence embedded
with text watermarking algorithms.
iii)After compiled RSA key Generator Testing, it
generating Public key and Private key. Then put a
public key in text based watermarking pool in figure
8. Invisibility and erase hidden data, due to PRNG
random bit sequence. it makes a hacker hard to
predict or crack it public key.
This paper also developed an experimental tool with JAVA
on windows according to the above embedding and
extracting algorithm for watermarking. The user interface
is shown in figure 8 below.
VI. CONCLUSIONS
In conclusion, this paper proposed a text based watermarking
algorithm
based
on
Pseudo-Random
Number
Generator(PRNG) for cryptography application. The paper has
also reported the experimental results shows that proposed
method has good invisibility and robustness to resist deletion,
modification attack, etc. Moreover, this algorithm can also be
applied in the information hiding area through cloud
computing, as the embedding method in this paper has large
information embedding capacity, which can be used for secret
communication of confidential information. The work of this
paper will give a help for further research direction as the
following.
 Our future research can extend further studies for advance
mathematics in chaotic functions theory[14].
 Further improvement watermarking method based on
double random phase encoding technique[16].
 Our future research can extend further studies for double
hash function for text based digital watermarking[15].
 It is possible to use these generator to provide PRNG
random bit sequences needed for highly parallel application
such as parallel grid computing, parallel genetic
programming, parallel cryptography, and parallel
computation analysis.
ACKNOWLEDGMENTS
C..H. Lew wishes to express his gratitude to Dr. Woo and Dr.
Ng as my PhD thesis supervisor for his valuable discussions on
the subject matter of the paper.
Mr. Lew Chee Hon obtained his Master of Computer Science
from Silicon Valley University, USA in 2004. Currently, he is
a PhD candidate at University of Malaya, also he also working
as IT lecturer at International College in China. His research
areas include Pseudo-random Number Generator, Digital
Watermarking and Cryptography. He is also an affiliate
member of British Computer Society and ACM since 2010,
also IEEE member and IAENG member in 2012.
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