<P> A major weakness of the system , however , was that no letter could be enciphered to itself . This meant that some possible solutions could quickly be eliminated because of the same letter appearing in the same place in both the ciphertext and the putative piece of plaintext . Comparing the possible plaintext Keine besonderen Ereignisse ( literally , `` no special occurrences '' -- perhaps better translated as `` nothing to report '' ) , with a section of ciphertext , might produce the following : </P>
what was the main weakness of the enigma machine
no letter could be enciphered to itself