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

ut there was no cryptographic advantage in using fewer. So, for example,
the 27 lugs might be distributed among the six wheels as
26 25 23 21 19 17
4 1 9 6 5 2
The number of lugs opposite a wheel is sometimes referred to as the ‘kick’
of that wheel. Thus the 26-wheel above has a ‘kick of 4’ etc. The ordering
is important; the cage above (4, 1, 9, 6, 5, 2) would not produce the same
key stream as, say, (9, 1, 4, 2, 6, 5) although there would be some statistical
similarity.
On the left hand side of the machine there was a small wheel engraved
with the alphabet; this was used for the input of the plaintext letter.
There was also a print wheel that printed the cipher letter on a thin strip
of paper tape. This tape had gum on the reverse side, the purpose of which
was to enable the operators to stick the cipher or plaintext onto sheets of
paper. A reel of this gummed paper was housed at the back of the machine
and there was also a notched screwdriver to enable the operators to set the
pins and the lugs.
On the right-hand side of the machine there was a handle which, when
rotated, would turn the cage and so encipher or decipher the text; this
handle also caused each of the six wheels to move forward one position.
To encipher a letter the operator turned the input wheel until the
chosen letter was opposite an arrow, and then turned the handle; the cage
rotated, some bars on the cage shifted and caused both the input wheel
and the print wheel to turn through anything from 0 to 27 positions. The
cipher letter was printed and the six wheels all moved 1 position. Another
letter could not be enciphered unless the input wheel had been moved by
the operator. If by chance it were in the position where the next letter was
opposite the arrow it was necessary to turn the wheel a few places forward
and then the same number of places back. So, if the last cipher letter was,
say, T and the next plaintext letter was also T the cipher operator would
have to move the input wheel a few places and then turn it back to T
before the handle would turn the cage.
For photographs of a Hagelin with its lid closed and open see Plates
10.1 and 10.2.
Encipherment on the Hagelin
The Hagelin cipher machine 135
Each wheel on the Hagelin had a number of pins sticking out to the left
and the remainder to the right. The operators would be told, at the start