to Suetonius, Caesar simply replaced each letter in a message with
the letter that is three places further down the alphabet. Cryptographers
often think in terms of the plaintext alphabet as being the alphabet
used to write the original message, and the ciphertext alphabet
as being the letters that are substituted in place of the plain
letters. When the plaintext alphabet is placed above the ciphertext
alphabet, as shown below, it is clear to see that the ciphertext
alphabet has been shifted by three places. Hence this form of substitution
is often called the Caesar Shift Cipher. A cipher is the name given
to any form of cryptographic substitution, in which each letter
is replaced by another letter or symbol.
your message into the box labelled 'Plaintext', then click the
button labelled 'Encipher Plaintext' to encrypt your message.
You can produce new versions of the cipher by changing the size
of the shift.