Ciphertext - Symmetric Key Example

Symmetric Key Example

Let be the plaintext message that Alice wants to secretly transmit to Bob and let be the encryption cipher, where is a secret key. Alice must first transform the plaintext into ciphertext, in order to securely send the message to Bob.

Both Alice and Bob must know the choice of key, or else the ciphertext is useless. Once the message is encrypted as ciphertext, Alice can safely transmit it to Bob (assuming no one else knows the key). In order to read Alice's message, Bob must decrypt the ciphertext using which is known as the decryption cipher, .