A known ciphertext attack is an an attack where the cryptanalyst only has access to encrypted ciphertext.
A known ciphertext attack is the easiest of the common cryptanalysis attacks to mount, because is requires the least amount of control over the encryption device.
Conversely, the known ciphertext is the most difficult of the common methods of cryptanalysis to execute successfully, because so little knowledge is known to begin with.
what are the techniques and methods used to break the ciphertext attack only?