# Caesar Cipher: Encode and Decode Online

The Caesar cipher is a type of substitution cipher in which each letter in the plaintext is replaced by a letter some fixed number of positions down the alphabet. For example, with a right shift of 3, A would be replaced D, B would be replaced by E, and so on. This encryption technique is named after Julius Caesar, who used it in his private correspondence. Other complex schemes like Vigenère cipher uses the Caesar cipher as one element of the encryption process. Another example is ROT13 encryption which is simply a Caesar cipher with an offset of 13. As with all monoalphabetic substitution ciphers, the Caesar cipher is easily broken and in modern practice offers essentially no communications security.

Use the above Caesar cipher decoder and encoder to encrypt and decrypt simple messages. The shift parameter is used as the **key** when converting plaintext to ciphertext and vice versa.