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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.
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This variant of the C-446 uses a paper tape reader
instead of the 6 cipher wheels. Using a tape reader
with a random cipher tape (RT) produces a much stronger
cipher. In fact, when the tape is truely random,
the cipher is unbreakable.
Unfortunately, most of the bars and lugs are missing
from this machine. They were removed as part of the
de-militarisation procedure, as can be seen in
image #4
and #5 below.
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The C-446 comes with a set of tools that are usually stored inside the
top cover. At the right are the screwdriver and the tweezers. At the left
are two metal containers.
All tools are clearly visible in the first image below.
One or more tools are often missing from machines found today.
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The tweezers are needed to feed the paper through the printer and to remove
any clotted paper from the mechanism.
The screwdriver is needed to disassemble certain parts and to make adjustments
to the mechanism. Please note the special gap in the blade of the screwdriver.
Also stored in the top cover are two small metal containers.
One contains oil that can be applied with a needle that is attached to the cap.
The other one contains a set of replacement ink rolls.
Please check the images below.
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The C-446 was usually supplied with a set of 4 keys: two operator's keys
and two officer's keys. They can be identified by the number of gaps in the
grip. The operator's key has one gap, whilst the officer's key
has two of them. The gaps are clearly visible in the images below.
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The operator's key can only be used to open the top cover, but the officer's
key can be used to open both the top cover and the machine itself.
The latter is needed in order to set the position of the pins and lugs
as part of the daily key.
The operator could only change the settings of the wheels (message key).
The keys of all C-446 machines are different and the chance that a key fits
another machine is very small. Furthermore, different versions of the cross-lock
have been used: long, small, simple, complex and safety versions.
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Most ex-Navy versions of the C-446 that ended up on the Dutch surplus market,
have their keys missing. And even worse: in most cases the machines are
locked. Over the years, we've seen many machines that were severely
damaged by a new owner, in an attempt to open the locks.
Our C-446-RT, for example, was locked and came without the keys.
In this case, we were lucky. We tried the keys of another C-446 unit and,
with a little wiggeling, we managed to open both locks.
Apparently, the locks of both machines were nearly identical.
Since then, we've tried the keys on many other machines, but to no avail.
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If you ever find a C-446 with the locks closed and without any keys present,
please don't attempt to open it yourself as you are likely to cause
permanent damage to the machine.
Instead try to find a good lock-picker.
Although cross-locks are rather complex, they can be opened
without damage.
The image on the right shows lock-picker Walter Belgers
(Netherlands) opening the C-446 of a friend at
the Dutch Radio Ham Museum in December 2008.
It took him about two minutes to open two machines.
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All cipher machines that were used by the Dutch Navy, were issued
a maintenance book (LIVRET), in which the complete history of the machine was
recorded. It contained a checklist, instructions for storing the machine
and written records of maintenance, repairs and overseas shipments.
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It is called LIVRET voor Chiffreermachines
(Pocket book for Cipher Machines).
It was issued by the Codedienst (Code Department) of the
Verbindingsdienst (Signals Department) of the Koninklijke Marine (Royal Dutch
Navy).
The image on the right shows an ex-Dutch Navy C-446-A with serial number 5224.
In front of the machine is the maintenance book which also carries serial
number 5224. The book measures 12 x 16 cm and has 20 pages. It starts with a
hand-written checklist followed instructions for storing the machine without
revealing the key.
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Maintanance books like these are extremely rare. In this case, it enables us
to trace the full history of the machine. Page 4 tells us that the machine
was received brand new from the factory on 9-6-1949. It was tested and
approved a day later by the chief of the technical department of the
MCD (Marine Code Department) mr. M. Vonk.
The machine was then stored for several months, until it was released to
S.O.C. Ned. on 13 April 1950, following a request of 6 April.
On 7 April 1954 the machine was returned to the MCD where it was subsequently
refurbished and re-issued. After that, the machine was returned several times
for maintenance or repairs. The last major maintenance recorded in the LIVRET
is of 9 November 1966. The last entry in the book is of 14 August 1988, which
is probably the last check before the machine was released to a museum.
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The image on the right proves that the C-446 was also used by the Royal
Dutch Airforce. The LIVRET was issued for a C-446A with serial number 5659,
which was received new from the factory on 1 January 1950. Five days later it
was tested and released for active duty.
According to the booklet, the machine has been used heavily and was repaired
and reworked a number of times. The last repair is dated 19 April 1964.
After that, the machine was anually tested and oiled.
The last entry in the book is dated 18 March 1966.
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The C-446 normally has an ID plate that is mounted over the lock in the top
cover, at the front of the machine. This ID plate is shown in the leftmost
image below. Quite often it is missing, as it was sometimes removed as part
of the de-militarisation process before the machines ended on the surplus
market.
The serial number can also be found at the front of the machine,
where it is engraved in the bottom plate. The image below shows the position
of that serial number.
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Many, if not all, of the C-446 machines that were used by the
Dutch Navy, were delivered by a company called Koopman & Co.
These machines have an additional manufacturer's plate attached to
their side. The Koopman & Co plate is shown in images
#4
and #5
below.
Koopman & Co was a trading company with offices in Amsterdam,
Bandoeng and Djakarta (in the former Dutch East-Indies). It is unclear
whether, apart from the name tag, they made any modifications to
the machine, prior to delivery to the Navy.
It is unlikely however.
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The C-446 machines used by the Norwegian Armed Forces had a manufacturer
tag that was painted to the back of the machine. It is shown in image
#3 below.
It shows that the machine was manufactured in Sweden by A.-B Cryptoteknik.
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The machine is usually opened with one of the keys (the operator's key or
the officier's key). The top cover is hinged at the rear and can not be
removed. After opening, the top cover should be locked into position with a
special spring-loaded bracket at the left (see picture
#1
below).
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In the images below it is shown how the top cover should be locked into
position. At the left of the machine - to the rear of the printer - is a shiny
spring-loaded metal bracket.
Rotate this bracket clockwise (i.e. towards the rear).
A gap in the bracket should mate
with a pin inside the top cover (at the left
side). You may have to open the cover a bit further to allow the bracket to
pass the pin first. Release the bracket and ensure that the pin has engaged
the gap.
Do not forget to release the bracket before closing the case again.
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Before the case of a Hagelin machine can be closed, the handle at the right
first has to be pushed down completely. If you are not familiar with
Hagelin machines, you may have trouble pushing down the lever to its home
position, sometimes leading to broken handles.
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Whatever you do, never use excessive force!
Although Hagelin machines are very robust and tough, axles can be broken
easily when enough force is applied. Once broken, these machines are very
difficult to repair.
If the lever won't come down, it's probably because the mechanism is blocked.
The most common reason for this is the fact that it always blocks
after (de)coding a letter. All you should do at this stage is selected another
input letter by rotating the letter knob at the left
(#2).
Now you should be able to bring the handle down.
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Once pushed down, lock the handle in place with the small lock
(#3).
Next, pull-out the grip (#4)
and fold it upright (#5).
Please check that the grip is full aligned (#6).
Ensure that the top cover is no longer locked in position,
by releasing the bracket at the left.
You may now close the case (#7).
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Depending on the model, a Hagelin machine takes one or two paper reels.
In the example below, we are showing how to load paper into a Hagelin C-446
machine. Please note that there are two different types of paper:
standard paper tape, and pre-gummed paper tape.
The paper is 9.65 mm wide and the hole at the centre of a reel is
±11 mm. A full roll is about 10 cm wide.
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Please be careful with pre-gummed paper. Over the years, this paper is
likely to have become brittle and will break easily. Furthermore,
gummed paper has the tendency to attract moist, making it sticky and
potentially block the machine.
Place the rolls in the lid of the machine and load them one at a time.
Lock the roll with the metal bracket that 'snaps' into position.
Then feed the machine over the first guide,
through the second guide,
into the printer.
Feeding it into the printer may be a bit tricky.
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Make sure the paper tape curls up a little before it is entered
through one of two slots at the rear of the printer mechanism,
so that it can be fed through the printer easily.
This is best done with the pincer that is usually stored in the top lid.
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The paper used in the C-446 is the same as used in the
M-209. It is very difficult to find these days and in
many cases, the pre-gummed tape has either become 'pudding' or brittle.
If you have any surplus rolls left, please contact us.
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The document below describes the Hagelin M-209 and the C-446A in great
detail. Not only is the working principle of the machines explained,
it also discusses the machine's cryptanalysis and methods for its attack.
The document is in Dutch and was released for publication
by the Dutch school for Military Intelligence (DIVI) in 2011.
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© Copyright 2009-2011, Paul Reuvers & Marc Simons. Last changed: Mon,09 Jan 2012.13:30:41
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