A basic Caesar Cipher class in PHP for fun and learning.

• Installation
• Instantiation
• Available Methods
  • Encrypt
  • Decrypt
  • Crack
• Security

Install the package using Composer.

composer require kkiernan/caesar-cipher

Create a new CaesarCipher instance. Make sure to import the class or use the fully qualified class name.

$cipher = new KKiernan\CaesarCipher();

To encrypt a message, pass the CaesarCipher instance some plaintext and a key. In a Caesar Cipher, the key is just the number of places to shift each letter in the plaintext.

$ciphertext = $cipher->encrypt('This is a plain text message that will be encrypted!', 8);

To decrypt a ciphertext, use the decrypt method on the CaesarCipher instance. Pass in the ciphertext and the key that was used to encrypt the message.

$plaintext = $cipher->decrypt($ciphertext, 8);

You can attempt to crack an encrypted message by using the crack method, which will return a best guess for the key's value. Use the key to retrieve the plaintext.

$key = $cipher->crack('Max wtrl tkx zxmmbgz lahkm tztbg.');

$plaintext = $this->decrypt($ciphertext, $key);

This was written for fun and learning very basic encryption techniques (like substitution in this case). Obviously Caesar Cipher is not a secure encryption algorithm (only 25 possible keys), so don't use this for anything sensitive. It's really a toy meant for fun.