Cryptography Reference
In-Depth Information
Another type of rotor
machine is much more like
the Vernam encryption sys-
tem (described previously
in "Substitution Ciphers").
Such devices are pin-and-lug
machines, and they typi-
cally consist of a collection
of rotors having a prime
number of labeled positions
on each rotor. At each posi-
tion a small pin can be set
to an active or inactive posi-
tion. In operation, all of the
rotors advance one position
at each step. Therefore, if the
active pin settings are chosen
appropriately, the machine
will not recycle to its initial
pin configuration until it has
been advanced a number of
steps equal to the product of
the number of positions in
each one of the rotors. One
machine of this type, the
Hagelin M-209 (named for
the Swedish engineer Boris
Hagelin), was used exten-
sively by the U.S. military
for tactical field communica-
tions during World War II. In
the M-209 the rotors have 26,
25, 23, 21, 19, and 17 positions,
respectively, so that the key
The German navy employed vari-
ous versions of the Enigma cipher
machine during the war, including
this four-rotor model.
Hagelin design M-209 U.S. cipher
machine used for tactical commu-
nications during World War II.
