Matlab Code to Enchipher and Dichipher Using Caesar Cipher

Caesar Cipher

The enciphering and Deciphering using Ceaser Cipher  has been illustrated below using the matlab code. Ansii decimal number for each letter is taken into consideration for the process. The code here is only suitable for the lower case letters without any spaces in between and it can be subsequently modified for Upper case letters using the corresponding ansii code. 

Initially when the code is run, it asks  for the key for the cipher. The Key must be in between 1 and 26. Once the key is fixed, the text to be ciphered has to be entered within single inverted comma in lower case letter without any spaces in between. Now, the given input text is ciphered.

Now, this code also does deciphering. Since the ciphered text has only 26 available combinations, all those combinations are tried and given as output of the deciphered text.

%% Matlab code to encipher and Decipher Caesar Cipher

% By: GG
% This is the demo code which enciphers and Deciphers using caesar cipher
% for all the lower case letters

%% inital command (clearing and closing)

clc
clear all
close all

%% input parameter

xin = input('Enter the cipher key xin_key_26; xin(between 1 and 26):  ' );  % enter the mode of ceaser cipher i.e. xmod26, here x = xin defines the shift
text_to_be_ciphered =input('ENter the text to be ciphered: ');

%% output_ciphered_parameter

ciphered_text = char(rem(text_to_be_ciphered + xin - 97,26)+97) % using the ansii decimal number for small letters which is from 97 to 122 ,...
...  were 97 corresponds a and 122 corresponds z, subtracting 97 results from 0 to 25;  
... and adding xin will provide the shift. remainder after division by 26 will give decimal number from 0 to 25  adding 97 to it corresponds to a to z. 

%% diciphered_text_crptoanyalysis

for pin = 1:26;
diciphered_text = char(rem(ciphered_text-pin - 97 +26,26)+97) % decipher is done in the similar way as encipher only difference is xin is subtracted rather than adding.
end