Re: All enemy comms readable by dawn each day
From what I remember from my cryptography course, the key failure of the enigma machine's use was that the Nazi's decided that they wanted to increase their security by using a random 3 letter, per message, key. They had to transmit the key to the receiver in an insecure channel, so they decided to encrypt the message key with the day key. To make sure that the message key was received, it was transmitted one more time. Meaning for ciphertext LKFUHFFGSFDGSAFS, the 1st character and 4th character map to the same plaintext, the 2nd and 5th, and the 3rd ad 6th chars. Then the remainder of the message was encoded using the message key After generating that mapping from several messages, chains of letter mappings would be used to limit the search space. The number of configurations, including plugboard usage, was 100,391,791,500, but by using this, the plugboard was negated, reducing the space to 105,391 configurations, and with a lookup table, could be used to determine the day key rotor positions. Paired with the tricks mentioned by other commentards, left them with the quick times described.