MODIFIED VERTICALLY SCRAMBLED CAESER CIPHER METHOD FOR ENHANCED DATA SECURITY
MODIFIED VERTICALLY SCRAMBLED CAESER CIPHER METHOD FOR ENHANCED DATA SECURITY
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Date
2016-01
Authors
ABDULKADIR, KHADIJA
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Abstract
Cryptography is the art and science of converting readable messages into non-readable form. The two techniques for converting data into non-readable form are transposition technique and substitution technique. Caesar cipher is an example of a substitution method. Although Caesar cipher is the simplest type of cipher, it suffers from the limitation of character repetition which makes it prone to plain text or brute force attack. Many researchers have developed techniques to address this problem by improving on key generation or combining two or more algorithms. Despite these efforts, the problem of character repetition still exists. To overcome this limitation, this work proposed a new data security solution using the modified Caesar cipher that eliminates character repetitions. The proposed system is expanded to include alphabets, numbers and symbols. The proposed method is resistant against brute-force attack with 256 keys. It also employs more confusion and diffusion to make the transmission of messages more secure and robust. The algorithm was evaluated based on frequency of character occurrence, character length, running time and security. The proposed system produced cipher texts with entropy value up to 60% higher and index of coincidence 11% lower than that of Vertically Scrambled Caesar Cipher Method. These enhancements are obtained at the expense of acceptable additional computation overhead (running time) of up to 15% in the worst case.
Description
A DISSERTATION SUBMITTED TO THE SCHOOL OF POSTGRADUATE STUDIES, AHMADU BELLO UNIVERSITY, ZARIA IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE AWARD OF MASTER OF SCIENCE DEGREE IN COMPUTER SCIENCE DEPARTMENT OF COMPUTER SCIENCE, FACULTY OF PHYSICAL SCIENCE AHMADU BELLO UNIVERSITY, ZARIA NIGERIA
Keywords
MODIFIED VERTICALLY SCRAMBLED CAESER CIPHER METHOD,, ENHANCED DATA SECURITY,