Text Encryption And Decryption Tool

K. Tarun Venkat B. Mohit K. Javali

Cse W/S IT Cse W/S IT Cse W/S IT
SRM Institute of Science and SRM Institute of Science and SRM Institute of Science and
Technology Technology Technology
Chennai, India Chennai, India Chennai,India
tk9623@srmist.edu.in mb4310@srmist.edu.in jk1975@srmist.edu.in

Abstract— Cryptography is the technique for hiding data In cryptography there are some important terms and are
and information from unauthorized users. It is the art of given below (figure 1):
achieving security by encoding messages to make them non- 1) Plaintext: It is the original text which has to be
readable. When we send simple message from one location to encrypted.
another then this message called plain text is visible to
2) Cipher Text: It is the encrypted text. The text obtain after
anybody. If we want to codify the message called cipher text so
that no one can easily understand the meaning of message then encoding the data with the help of a key is known as cipher
we use cryptography techniques. There are numerous text.
applications where this technology is used such as ATM pin, 3) Key: It is a word or value that is used to encrypt the plain
Password, Credit Card number or any other secret text or decrypt the cipher text.
communication. Cryptography can be divided into following 4) Encryption: The method of converting the data into coded
three categories depending upon the types of key used: secret form with the help of key is called encryption [4].
key (symmetric) cryptography, public key (asymmetric) 5) Decryption: The method of converting the encoded data
cryptography and hash functions. In this paper we provide to the original form is called decryption.
review of various types of cryptography techniques.
6) Crypto Analyst: A crypto analyst is a person who is an
Keywords: Cryptography, plain text, cipher text, expert in analyzing and breaking codes [3].
cryptanalyst)

I. INTRODUCTION (HEADING 1)
Cryptography, then, not only protects data from theft or
alteration, but can also be used for user authentication.
Cryptography can be divided into following three categories
depending upon the types of key used: secret key
(symmetric) cryptography, public key (asymmetric)
When we send simple message from one location to
cryptography and hash functions. The rapid continuous another then this message called plain text is visible to
increase in exchange of multimedia data over protected and anybody. If we want to codify the message called cipher
unprotected networks such as the worldwide available text so that no one can easily understand the meaning of
internet and local networks such as shared networks and message then we use cryptography techniques. The work
local area networks etc has encouraged activities such as presented in this paper is to study the existing encryption
unauthorized access, illegal usage, disruption, alteration of algorithm used for data security.
transmitted and stored data. This widely spread use of
digital media over the internet such as on social media, on II. CLASSICAL CRYPTOGRAPHY TECHNIQUES
cloud storage systems etc and over other communication
medium such as satellite communication systems have The technique enables us to illustrate the basic
increased as applications and need for systems to meet approaches to conventional encryption today. The two basic
current and future demands evolved over the years. Security components of classical ciphers are substitution and
transposition [3]. Then other systems described that
concerns with regards to such data transmission and storage
combines both substitution and transposition.
has been a major concern of both the transmitters and
receivers and hence the security of critical cyber and A. Substitution Techniques In this technique letters of
physical infrastructures as well as their underlying plaintext are replaced by or by numbers and symbols. If
computing and communication architectures and systems plaintext is viewed as a sequence of bits, then substitution
becomes a very crucial priority of every institution. involves replacing plaintext bit patterns with cipher text bit
Cryptography is the fundamental platform in which modern patterns.
information security, which involves the use of advanced 1) Caesar Cipher Caesar Cipher replaces each letter of
mathematical approaches in solving hard cryptographic
the message by a fixed letter a fixed distance away e.g. uses
issues, has gained its grounds in the digital world. This has
the third letter on and repeatedly used by Julius Caesar.
evolved from classical symmetric, in which shifting keys are For example:
normally used as well as substitution methods, ciphers to
modern public key exchange cryptosystems, which aims to Plaintext: I CAME I SAW I CONQUERED
make cryptanalysis a difficult approach to deciphering Cipher text: L FDPH L VDZ L FRQTXHUHG
ciphers.

XXX-X-XXXX-XXXX-X/XX/$XX.00 ©20XX IEEE

 Mapping is: ABCDEFGHIJKLMNOPQRSTUVWXYZ 1) Repeating plaintext letters that would fall in the same
DEFGHIJKLMNOPQRSTUVWXYZABC pair are separated with a filler letter, such as x, so that
balloon would be enciphered as ba lx lo on.
Can describe the Cipher as:
2) Plaintext letters that fall in the same row of the matrix
Encryption: C = E (P) = (P + 3) mod 26
are each replaced by the letter to the right, with the first
Decryption: P = D(C) = (C - 3) mod 26 element of the row circularly following the last. For
example, ar is encrypted as RM.
3) Plaintext letters that fall in the same column are each
2) Mono Alphabetic Ciphers replaced by the letter beneath, with the top element of the
row circularly following the last. For example, mu is
With only 25 possible keys, the Caesar cipher is far from encrypted as CM.
secure. A dramatic increase in the key space can be achieved 4) Otherwise, each plaintext letter is replaced by the letter
by allowing an arbitrary substitution. Recall the assignment that lies in its own row and the column occupied by the
for the Caesar cipher: other plaintext letter. Thus, hs becomes BP and ea
plain: a b c d e f g h i j k l m n o p q r s t u v w x y z becomes IM (or JM, as the encipherer wishes).

cipher: D E F G H I J K L M N O P Q R S T U V W X Y Z
ABC The Playfair cipher is a great advance over simple
If, instead, the "cipher" line can be any permutation of the 26 monoalphabetic ciphers. For one thing, whereas there are
alphabetic characters, then there are 26! possible keys. This only 26 letters, there are 26 * 26 = 676 diagrams, so that
is 10 orders of magnitude greater than the key space for DES identification of individual diagrams is more difficult.
and would seem to eliminate brute-force techniques for Furthermore, the relative frequencies of individual letters
cryptanalysis. Such an approach is referred to as a mono exhibit a much greater range than that of diagrams,
alphabetic substitution cipher, because a single cipher making frequency analysis much more difficult. Despite
alphabet (mapping from plain alphabet to cipher alphabet) is this level of confidence in its security, the Playfair cipher
used per message. is relatively easy to break because it still leaves much of
the structure of the plaintext language intact. A few
hundred letters of ciphertext are generally sufficient.
3) Playfair Cipher

The Playfair is a substitution cipher bearing the name of the B. Transposition Techniques
man who popularized but not created it. The method was All the techniques examined so far involve the
invented by Sir Charles Wheatstone, in around 1854; substitution of a ciphertext symbol for a plaintext
however he named it after his friend Baron Playfair. The symbol. A very different kind of mapping is achieved by
Playfair Cipher was developed for telegraph secrecy and it performing some sort of permutation on the plaintext
was the first literal digraph substitution cipher. The best- letters. This technique is referred to as a transposition
known multiple-letter encryption cipher is the Playfair, cipher.
which treats digrams in the plaintext as single units and
The simplest such cipher is the rail fence technique, in
translates these units into ciphertext digrams. The Playfair
which the plaintext is written down as a sequence of
algorithm is based on the use of a 5 * 5 matrix of letters
diagonals and then read off as a sequence of rows. For
constructed using a keyword. Here is an example:
example, to encipher the message "meet me after the toga
party" with a rail fence of depth 2, we write the
following:
me mat rh t gp ry
etefeteoaat
The encrypted message is:
MEMATRHTGPRYETEFETEOAAT
This sort of thing would be trivial to crypt analyze. A
more complex scheme is to write the message in a
rectangle, row by row, and read the message off, column
by column, but permute the order of the columns. The
In this case, the keyword is monarchy. The matrix is order of the columns then becomes the key to the
constructed by filling in the letters of the keyword (minus algorithm. For example:
duplicates) from left to right and from top to bottom, and
then filling in the remainder of the matrix with the
remaining letters in alphabetic order. The letters I and J
count as one letter. Plaintext is encrypted two letters at a
time, according to the following rules:
 III. CONCLUSION

Data security is an essential component of an

organization in order to keep the information safe from
various competitors. It helps to ensure the privacy of a
user’s personal information from others. Secured and
timely transmission of data is always an important
aspect for an organization. Strong encryption algorithms
and optimized key management techniques always help
in achieving confidentiality, authentication and integrity
of data and reduce the overheads of the system.
A pure transposition cipher is easily recognized because it Cryptography is a technique used to avoid unauthorized
has the same letter frequencies as the original plaintext. For access of data. It has two main components;
the type of columnar transposition just shown, cryptanalysis a) Encryption algorithm,
is fairly straightforward and involves laying out the
ciphertext in a matrix and playing around with column b) Key. Sometime, multiple keys can also be used for
positions. Digram and trigram frequency tables can be encryption.
useful. The transposition cipher can be made significantly
more secure by performing more than one stage of In this paper we studied the existing encryption
transposition. The result is a more complex permutation that algorithm used for data security.
is not easily reconstructed. Thus, if the foregoing message is
re-encrypted using the same algorithm:

To visualize the result of this double transposition, designate

the letters in the original plaintext message by the numbers
designating their position. Thus, with 28 letters in the
message, the original sequence of letters is:

01 02 03 04 05 06 07 08 09 10 11 12 13 14
15 16 17 18 19 20 21 22 23 24 25 26 27 28

After the first transposition we have:

03 10 17 24 04 11 18 25 02 09 16 23 01 08

15 22 05 12 19 26 06 13 20 27 07 14 21 28

which has a somewhat regular structure. But after the

second transposition, we have:

17 09 05 27 24 16 12 07 10 02 22 20 03 25

15 13 04 23 19 14 11 01 26 21 18 08 06 28

This is a much less structured permutation and is much more

difficult to crypt analyze.
REFERENCES IEEE Transaction on Mobile Computing, Vol. 5, No. 2,
[1] W. Stallings; “Cryptography and Network Security” pp. 128-143, 2006. [16] D. Anand, V. Khemchandani, R.
2nd Edition, Prentice Hall,1999 [2] Bruce Schneir: K. Sharma, “Identity Based Cryptography Techniques
Applied Cryptography, 2nd edition, John Wiley & Sons, and Applications”, International Conference on
1996 [3] A. Kakkar and P. K. Bansal, “Reliable Computational Intelligence and Communication
Encryption Algorithm used for Communication”, M. E. Networks, Vol. 1, pp. 343-348, 2013. [17] Pavan. N,
Thesis, Thapar University, 2004. [4] N. Koblitz, Nagarjun G. A, Nihaar N, G. S Gaonkar and P. Sharma,
“Elliptic Curve Cryptosystems”, Journal of Mathematics “Image Steganography Based On Hill Cipher with Key
of Computation. Published by American Mathematical Hiding Technique”, IOSR Journal of Computer
Society, Vol. 48, No. 177, pp. 203- 209, 1987. [5] H. Engineering, Vol. 11, pp. 47-50, 2013. [18] K. R. Saraf,
Krawczyk, “The Order of Encryption and Authentication V. P. Jagtap, A. K. Mishra, “Text and Image Encryption
for Protecting Communications, Decryption Using Advanced Encryption Standard”,
http://eprint.iacr.org/2001. [6] L. Eschenauer, V. D. International Journal of Emerging Trends & Technology
Gligor, “A Key Management Scheme for Distributed in Computer Science (IJETTCS) Volume 3, Issue 3, May
Sensor Networks”, ACM conference on Computer – June 2014 [19] S. Desai, C. A. Mudholkar, R. Khade,
Security, Vol.2, pp. 41-47, 2002. [7] Jung. W. Lo, M. S. P. Chilwant, “Image Encryption and Decryption using
Hwang, C. H. Liu, “An efficient key assignment scheme Blowfish Algorithm”, International Journal of Electrical
for access control in a large leaf class hierarchy”, and Electronics Engineers IJEEE, Volume 07, Issue 01,
Journal of Information Sciences Elsevier Science, Vol. 4, June 2015. [20] B. Persis Urbana Ivy, “A Simple and
pp. 917-925, 2003. [8] B. B. Madan, K. G. Efficient Counting Algorithm for Data Encryption and
Popstojanova, K. Vaidyanathan and K.S. Trivedi, “A Decryption”, Taga Journal Vol. 14, 2017. [21] D.
Method for Modeling and Quantifying the Security Maheswari, A. Kaushika, A. Jenifer, “ A Study on Data
Attributes of Intrusion Tolerant Systems”, Journal of Encryption and Decryption Using Hill Cipher
Performance Evaluation, Elsevier Science Publishers, Algorithm”, International Journal of Technical
Vol. 56, No. 1, pp. 167-186, 2004. [9] T. Jamil, “The Innovation in Modern Engineering & Science (IJTIMES)
Rijndael Algorithm”, IEEE Potential, Vol.1, pp. 1-4, e-ISSN: 2455-2585 Volume 4, Issue 03, March-2018.
2004. [10] H.W. Kim, S. Lee, “Design and [22] Ali Mohammed Ali Argabi, Md Imran Alam, “A
Implementation of a Private and Public Key Crypto new Cryptographic Algorithm AEDS (Advanced
Processor and Its Application to a Security System”, Encryption and Decryption Standard) for data security”,
IEEE Transactions on Consumer Electronics, Vol. 50, International Advanced Research Journal in Science,
No. 1, pp. 214-224, 2004. [11] P. Gope, A. Singh, A Engineering and Technology Vol. 6, Issue 10, October
Sharma, N. Pahwa, “An Efficient Cryptographic 2019. [23] Borislav Stoyanov, Gyurhan Nedzhibov,
Approach for Secure Policy Based Routing”, IEEE “Symmetric Key Encryption Based on Rotation-
Journal on Selected Areas in Communications, Vol. 1, Translation Equation”, Symmetry 2020, 12, 73;
pp. 359-363, 2013. [12] I. I. A, A. Mohammed, D. doi:10.3390/sym12010073 [24] Subhi R. M. Zeebaree,
Hossam, “How to repair the Hill cipher”, Journal of “DES encryption and decryption algorithm
Zhejiang University Science, Vol. 1, pp. 2022-2030, implementation based on FPGA”, Indonesian Journal of
2006. [13] Y. Karandikar, X. Zou, Y. Dai, “An Effective Electrical Engineering and Computer Science Vol. 18,
Key Management Approach to Differential Access No. 2, May 2020, pp. 774~781. [25] Pronika, S. S.
Control in Dynamic Environments”, Journal of Tyagi, “Performance analysis of encryption and
Computer Science, Vol. 1, pp. 542-549, 2006. [14] Y. decryption algorithm”, Indonesian Journal of Electrical
Zhang, W. Liu, W. Lou, Y. Fang, “Location Based Engineering and Computer Science Vol. 23, No. 2,
Compromise Tolerant Security Mechanisms for Wireless August 2021. [26] Guanxiu Liu, “The Application of
Sensor Networks”, IEEE Transactions Selected Areas in Data Encryption Technology in Computer Network
Communications, Vol. 24, No. 2, pp. 1-14, 2006. [15] N. Communication Security”, Hindawi Mobile Information
R. Potlapally, S, Ravi, A. Raghunathan, N. K. Jha, “A Systems, Volume 2022
Study of the Energy Consumption Characteristics of
Cryptographic Algorithms and Security Protocols”,