Ciphertext definition

Encrypted information created by running plaintext through an encryption algorithm (a cipher). Data stored in ciphertext looks like random gibberish and is virtually impenetrable without proper decryption keys.

Real ciphertext examples

c. 30 BC: Gaius Julius Caesar used the Caesar cipher to protect his communications. It substitutes each letter in a message by another several positions down the alphabet.

World War II: Germany used the Enigma cipher for wartime messages. The Enigma machine substituted letters based on time-sensitive settings known only to its operators.

Further reading