Caesar Cipher using Java

This project is designed for encrypting and decrypting the text using Java Programming Language.

The Caesar Cipher is the simplest and oldest encryption technique. It is a method in which each letter in the plaintext is replaced by a letter with some fixed number of positions down the alphabet. For this reason, the shift cipher technique is called the Caesar cipher. The Caesar cipher is a kind of replacement (substitution) cipher, where all letter of plain text is replaced by another letter. It works with alphabets only.

PlainText means readable text. For eg: Hello everyone.

CipherText means text that has been encrypted and therefore unreadable. For eg: $%UFU%F^R

Formulas

1.)For Encryption : E(x) = ( pt + n ) mod 26

2.)For Decryption : D(x) = ( ct - n ) mod 26

where

pt denotes plaintext.

ct denotes ciphertext.

n denotes the key value.

E and D denote Encryption and Decryption.

In the above, if the result is not in the range 0 - 25 i.e. if pt+n and ct-n are not in the range 0 - 25 then we have to add or subtract 26.

For example: If D is -3 then add -3 with 26 and 23 as the answer.