Caesar cipher is a symmetric key cryptosystem, which is a cryptographic protocol that encrypts a plaintext by shifting it by the numerical value of the key, and decrypts a ciphertext by shifting it by the numerical value of the key in reverse.
For example, if the plaintext is HELLO and the key is 3, the ciphertext will be KHOOR, since the key is shifted by 3 from H to I to J to K.

Let's try to eavesdrop on the ciphertext of the Caesar cipher floating on the network and try to decipher it.

Let's try clicking the "Eavesdrop on ciphertext" button below. You will get the ciphertext.

Ciphertext

Next, let's try to decrypt the above ciphertext using a computer. Try entering a key number in the text box below. The computer will automatically decrypt it using the key you entered.