ShiftCipher_BruteForce

Author: Mark Tullier
Last Edited: 01/30/2021 10:01PM
Desc: This program was developed for CIS491: Intro to Cryptography at CSU-Pueblo. The user inputs a string that has been encrypted with a shift cipher, and the program does its best to pull the decrypted string with a distance calculation using frequency tables. There are two tables used in the calculation: a model table of the English language, trained on the first chapter of a book called "Ender's Game", and the frequency table of the shifted string (which is iterated over 25 times). The program accepts the two tables into a function where the difference of each pair of index values is squared, added to the total, and finally returned after the square root of the total is found. Each of these distances is stored in a list that then has the index position of the smallest value taken from it and compared against the index position of a list that holds all of the decrypted string possibilities. The final result returned should, in theory, be the correct decryption, depending on how much text you've trained the model table on; the larger your sample size, the more accurate your results will be for the population. Granted, the program is quite hamfisted in the ways that it tackles each individual challenge associated with such an application; however, I'm just honestly glad it works :)