Code and ciphers: Julius Caesar, the Enigma and the internet

columns in each case, are full of contradictions; so we reject the hypothesis
that R1 was set at position 1 at the encipherment of the indicators. If
we now encipher the same pairs at settings (3 and 4) we get Table S.9, and
these pairings are completely consistent. Any other combination of chain
alignment and setting of R1 would lead to contradiction. We therefore
conclude that R1 was set at position 3 at the start of the encipherment of
the indicators at the ground setting. If this is so, the pairings in the composite
reflector are (0, 5), (1, 3), (2, 8), (4, 7), and (6, 9).
Table S.9
Pair Setting 3 Pair Setting 4
(5, 7) (6, 9) (5, 7) (9, 6)
(1, 9) (4, 7) (1, 0) (2, 8)
(8, 0) (3, 1) (8, 2) (0, 5)
(4, 2) (8, 2) (4, 3) (1, 3)
(6, 3) (5, 0) (6, 9) (7, 4)
Chapter 10
10.1 (Hagelin message)
Since the cage is (0, 5, 5, 5, 5, 5) the only keys that can occur are 0, 5, 10, 15,
20 and 25 with relative frequencies 1, 5, 10, 10, 5 and 1. We write down
six lines showing what the ‘plaintext’ would be if the key value were 0, 5,
10, 15, 20 or 25 at each position of the text using the Hagelin decipherment
rule:
plaintext letter�key�cipher letter.
The cipher and six lines corresponding to the six keys are shown in Table
S.10.
Table S.10
Cipher CBZPC CJXWY CXSHN IQUSR
Key�0 YZBLY YRDEC YDITN SKGIJ
Key�5 DEGQD DWIJH DINYS ^PLNO
Key�10` IJLVI IBNOM INSD^ CUQST
Key�15 NOQAN NGSTR NS^IC HZV^Y
Key�20 STVFS SL^YW S^CNH MEACD
Key�25 ^YAK^ ^UCDB ^CHSM RJFHI
Solutions to problems 227