On Encryption with Continued Fraction

Abstract

Many mathematicians have investigated the properties of continued fractions. They made continued fraction expansions of the Pi number, the golden ratio and many more special numbers. With the help of continued fractions, solutions of some Diophantine equations are obtained. In this study, encryption was made using continued fractional expansions of the square root of non-perfect-square integers. Each of the 29 letters in the alphabet is represented by the root of nonperfect square integers starting from 2. Then, continued fraction expansions of the square root of each letter’s number equivalent were calculated. Afterwards, all numbers in the continued fraction expansion were considered as an integer by removing the comma. This information was tabulated for later usage. Each word is considered as individual letters, and a space is left between the encrypted versions of each letter. After the encryption process, the process of deciphering the encrypted text was dealt with. In the deciphering process, since there is a blank between the numbers, the numbers are written as a continued fraction and the integer expansion is calculated. Later, the letter corresponding to this number was found.