Editing Ciphertext-only attack (section)

==Attack==
The attack is completely successful if the corresponding [[plaintext]]s can be deduced, or even better, the [[key (cryptography)|key]].  The ability to obtain any information at all about the underlying plaintext beyond what was pre-known to the attacker is still considered a success. For example, if an adversary is sending ciphertext continuously to maintain [[traffic-flow security]], it would be very useful to be able to distinguish real messages from nulls. Even making an informed guess of the existence of real messages would facilitate [[traffic analysis]].  

In the [[history of cryptography]], early ciphers, implemented using pen-and-paper, were routinely broken using ciphertexts alone. Cryptographers developed statistical techniques for attacking ciphertext, such as [[frequency analysis (cryptanalysis)|frequency analysis]]. Mechanical encryption devices such as [[Enigma (machine)|Enigma]] made these attacks much more difficult (although, historically, Polish cryptographers were able to mount a successful ciphertext-only [[cryptanalysis of the Enigma]] by exploiting an insecure protocol for indicating the message settings). More advanced ciphertext-only attacks on the Enigma were mounted in [[Bletchley Park]] during [[World War II]], by intelligently guessing plaintexts corresponding to intercepted ciphertexts.