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The C-446 was a mechanical cipher machine developed in
1944/1945 by Boris Hagelin of A.B. Cryptoteknik in
Stockholm (Sweden). The design is clearly based on the
earlier
M-209. It comes in a similar sturdy case and is very
robust and reliable. The tools are stored in the top
lid.
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Unlike the M-209 however, the C-446 is locked with two
different keys (see below).
Furthermore, it has two different printers, one for the
plain text and one for the cipher text. Two separate
paper reels have to be mounted inside the top lid.
Three versions of the C-446 are known:
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Although we know that the RT version uses a one-time pad
(OTP) cipher tape, rather than cipher wheels, the
differences between the C-446 and the C-446-A are
currently unknown. It is quite likely though that the
A-extension only refers to small manufacturing
changes, just like with the M-209 A and B models.
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The C-446 came in commercial (grey) and military (green)
variants. Apart from the outer colour, they were
functionally identical. The machines shown on this page
are all of the military type and were used by the Dutch
Navy and the Norwegian Army.
The image on the right shows both versions side by side.
The one on the right is the standard C-446-A that has 6
cipher wheels. The leftmost one has a 5-bit tape reader
instead of the wheels. It uses a so-called One Time Tape
(OTT) and is theoretically unbreakable. |
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Many C-446 machines that have been found in recent
years, appear to be incomplete due to de-militarisation
procedures when they were finally scrapped. As a result,
some of the bars and lugs are missing from the cage
inside the machine. In many cases, even the serial
number plates have been removed.
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The machine shown below is a standard C-446-A. At first
sight it is very similar to the war-time
M-209, which in turn was based on the civil
C-38. The machine has 6
non-removable cipher wheels that protrude the top lid at
the bottom right. To the left of the wheels is a small
letter-counter. At the far left are the two printers.
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Unlike the M-209, the C-446 can be locked properly. It
has a lock on the top cover and one on the machine
itself. Both locks are different, so different keys were
supplied with each machine. One key could only open the
cover, whilst the other key (the so-called officer's
key) could open both locks (see below).
The machine is operated by a crank at the right. In the
image, the crank is shown upright, in the operational
position. The mechanism is operated by pressing the
handle down to the front of the machine (carefully).
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Different versions of the C-446-A are known. The two
rightmost images below show two variants. The one on the
right has some additional mechanics just behind the
printer. This was used to allow it to be driven by an
external keyboard attachment. Strangely, there is no way
to tell these differences from the model number of the
machine. br />
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