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DATA ENCRYPTION
Olufohunsi, T.
Post Graduate Student,
Cyber Security, Threat Intelligence and Forensics
University Of Salford, Manchester
What is Data?
Datum (plural Data) in its simplest form of
understanding refers to information (Bard) that
is collected together for reference and analysis,
but it goes beyond that as information is
actually processed data. Raw data also referred
to as source data are data that has not been
processed. There are different forms of data
which include Big Data, Time-stamped data,
Machine data etc.
What is Encryption?
Encryption is the process of converting
information or a message which is referred to
as plaintext into a difficult unreadable form
called ciphertext by using an encryption
algorithm (Bassel). It is derived from the Greek
word "kryptos" which is translated as hidden.
There are mainly two types of Encryption
namely Symmetric and Asymmetric Encryption
Symmetric Encryption involves having a singular
key to both encrypt the plaintext into ciphertext
and decrypt the ciphertext into plaintext.
Asymmetric Encryption involves having two
keys (one public and the other private) whereby
one is used to encrypt the plaintext and the
other to decrypt the ciphertext.
HISTORY OF ENCRYPTION IN CRYPTOGRAPHY
The use of cryptography can be dated back to
when humans had the need to hide messages
not intended for certain parties.
Ancient form of cryptography was mainly
divided into two categories which are
Transposition and Substitution ciphers.
Transposition ciphers involve rearranging the
order of alphabets, for example the first
character of the alphabet becomes the last and
so on. Substitution ciphers involve replacing a
letter in the alphabet or a group of letters with
another letter in the alphabet or group of
letters (Pandya et al.
, 2015).
Medieval form of cryptography came to be after
an Arab mathematician and polymath named
Al-Kindi discovered the frequency analysis in
the 9th century which made it easy to decipher
texts originally encrypted using the ancient
forms of cryptography. Although the method
was claimed to have been previously
developed, the Alberti Cipher was one of the
first to implement polyalphabetic ciphers which
made use of a cipher disk comprising of two
concentric disks which had alphabet and
numbers inscribed on both. It was created by
cryptographer Leon Battista Alberti in 1467. He
was titled "Father of Western Cryptography" by
cryptography historian David Khan (Khan,
1973).The first printed book on cryptology was
written by Johannes Trithemius and it brought
to light the elementals of polyalphabetic
substitution in the form of a tableau as known
as tabula recta. This formed the foundation of
the Vigenere cipher (aka autokey cipher) which
was outrightly misattributed to Blaise de
Vigenere instead of Giovan Battista Bellaso
according to David Khan.
The Vigenere cipher was said to have been
unbreakable by authors but was broken by
Charles Babbage and between 1853-1856, he
developed techniques to break polyalphabetic
ciphers. There were advancements in
cryptography in the period of World War I and II
which included the invention of one-time pad
(Gilbert Vernam), Enigma Machine (Germans),
VIC cipher (Soviets), JN-25 (Japanese navy) etc.
In modern times, there are a number of
methods used for encryption. These include
Triple DES, RSA, Blowfish, AES, IDEA, SHA1,
MD5.
IMPORTANCE OF DATA ENCRYPTION
This age has seen the rise of data which is
currently the most valuable asset on earth. This
means that companies, organizations, groups
and people would pay a lot of money just to get
data on a particular subject matter.
Back in the ancient and medieval days,
encryption was mainly used for communication
between two parties that required a third party
not being able to understand the messages
between the other two parties.
Nowadays, encryption has gone beyond
communication but also securing data from
people like hackers and cybercriminals. With
the rise and advancement of digital technology
in different sectors of economy, businesses that
make use of such digital technology are made
aware of threats to their businesses by
cybercriminals hence why they need to secure
their data and this security is mainly done
through encryption.
A quick description of some Data Encryption
methods used in recent times are given below.
Triple DES
Also known as 3DES, this works on the principle
of DES (Data Encryption Standard or Data
Encryption Algorithm).
“The DES algorithm enciphers and deciphers
data in 64-bit blocks under the control of a
56-bit key. The algorithm comprises 19 distinct
stages:
1: a key-independent initial transposition on the
64-bit input data;
2-17: sixteen identical iterations (‘rounds’),
processing the data under the control of the
key;
18: a final swap of the leftmost 32 bits with the
rightmost 32 bits;
19: a key-independent final transposition on the
64-bit output data.
The algorithm is symmetric in that decryption is
performed with exactly the same key as
encryption, but the sixteen central iterations
are merely carried out in reverse order.”
(Shepherd, 1995)
DES is a symmetric block cipher whose block
size is 64 bits but only makes use of 56 bits for
its key length as a result of regulations set by
the NSA in the United States of America. The
other 8 bits are used for parity and are then
discarded after use.
3DES applies DES three times to each block of
data and the key length is summed up to be 112
bits or 168 bits but block size remains 64-bit
length. 3DES was created to counter the
weakness of DES, which was broken using brute
force attacks and cryptanalytic attacks, without
having to redesign or change the design of the
block cipher algorithm.
RSA
RSA (Rivest–Shamir–Adleman) is an asymmetric
cryptographic cipher that utilizes prime
numbers to generate two keys, one for
encryption (public key) and the other or
decryption (private key). With these keys,
plaintext can be encrypted using the public key
and decrypted using the private key (Patil et al.
,
2016).
Blowfish
It is a symmetric block cipher that made use of
key length variables of 32 to 448 bits and block
size of 64 bits. First published in 1993, it was
designed by Bruce Schneier as a fast and free
alternative to existing encryption algorithms
(DES and IDEA). Data Encryption occurs via a
16-round Feistel Network (Schneier, 1993).
International Data Encryption Algorithm (IDEA)
Initially known as Improved Proposed
Encryption Standard (IPES) when published by
Xueija Lai, James Massey and Sean Murphy in
1991, it was designed as a replacement for DES.
IDEA encrypts a 64-bit block of plaintext to
64-bit block ciphertexts. It uses 128-bit key. The
algorithm consists of eight identical rounds and
a "half" round final transformation (Hoffman,
2007). However, because of more advanced
cryptosystems that make use of 128-bit blocks
like AES, IDEA has become somewhat obsolete.
AES
This is arguably one of the best encryption
methods available nowadays for data security
and it has the added advantage of being
implemented in both hardware and software.
"AES is a non-Feistel cipher that encrypts and
decrypts a data block of 128 bits. It uses 10, 12,
or 14 rounds in algorithm and the key size, can
be 128, 192, or 256 bits depending on the
number of rounds" (Rahman, Miah and Azad,
2014).
REFERENCES
Bard, J. (no date) What is data mining?
Bassel, E.-S. (no date) ‘Caesar Cipher Encryption
& other types of encryption’.
Hoffman, N. (2007) ‘A simplified IDEA
algorithm’, Cryptologia
, 31(2), pp. 143–151. doi:
10.1080/01611190701215640.
Khan, D. (1973) ‘The Codebreakers’, pp. 1–473.
Pandya, D. et al.
(2015) ‘Brief History of
Encryption’, International Journal of Computer
Applications
, 131(9), pp. 28–31. doi:
10.5120/ijca2015907390.
Patil, P. et al.
(2016) ‘A Comprehensive
Evaluation of Cryptographic Algorithms: DES,
3DES, AES, RSA and Blowfish’, Procedia
Computer Science
. Elsevier Masson SAS,
78(December 2015), pp. 617–624. doi:
10.1016/j.procs.2016.02.108.
Rahman, A. U., Miah, S. U. and Azad, S. (2014)
‘Advanced encryption standard’, Practical
Cryptography: Algorithms and Implementations
Using C++
. Elsevier Ltd, 2009(12), pp. 91–126.
doi: 10.1201/b17707.
Schneier, B. (1993) ‘Descripton of a New
Variable-Length Key, 64-Bit Block Cipher
(Blowfish)’, pp. 1–7.
Shepherd, S. J. (1995) ‘A high speed software
implementation of the Data Encryption
Standard’, Computers and Security
, 14(4), pp.
349–357. doi: 10.1016/0167-4048(95)00007-U.
