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

88
chapter 7
From CT2: (cipher�key) at position 5�plaintext letter at position
5; i.e.
S�O�E.
From CT1: (cipher�plain) at position 5�key letter at position 6;
i.e.
H�E�D.
From CT2: (cipher�key) at position 6�plaintext letter at position
6; i.e.
H�D�E.
From CT1: (cipher�plain) at position 6�key letter at position 7;
i.e.
M�E�I.
From CT2: (cipher�key) at position 7�plaintext letter at position
7; i.e.
L�I�D.
From CT1: (cipher�plain) at position 7�key letter at position 8;
i.e.
O�D�L.
From CT2: (cipher�key) at position 8�plaintext letter at position
8; i.e.
I�L�X.
Looking at the recovered key and message texts so far we have
Key: ... F O D I L
Message ... N E E D X
This looks quite promising, so:
Problem 7.3
Complete the solution which has been started above.
‘Garbo’’s ciphers
The ‘double agent’ Jean Pujol (codename garbo), a Spaniard, used both
secret inks and cipher systems during his time in England (1942–5). The