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Pin-wheel cipher machine

The H-54 was a mechanical pin-wheel cipher machine, built in the mid-1950s by Rudolf HELL in Kiel (Germany) for the German Bundeswehr (Army). It was a functional replica of the Hagelin CX-52 and was built under licence from the Boris Hagelin Company (now: Crypto AG) in Switzerland. The machine is interoperable with the HELL STG-61 (and therefore also with the Hagelin CD-57).
Nevertheless, HELL managed to improve several aspects of the machine and make it easier to operate and more relibable. As the machine was built for the army, it is slightly more robust than the original CX-52 design. Furthermore, the storage case houses all spares and maintenance tools that were required for daily use.

The machine is housed in a aluminum case with a metal dust cover. All metal parts are painted in the typical Bundeswehr green colour. The image on the right shows a typical H-54 with its dust cover open and the transport handle raised.
HELL H-54 cipher machine

The machine was exclusively made for the German market. The various notes and checklists are in the German language and so are the settings for ciphering and deciphering (V/E rather than C/D). In order to accomodate the spares and maintenance tools, HELL improved the metal storage case and designed an ingenious storage compartment in the top section of the dust cover.

The paper reel is stored in a third compartment, at the bottom of the machine. After removing the retaining clip at the center of the bottom, the paper compartment can be opened. The paper tape is fed through a guide into the bottom of the printer. On the top side, the paper is fed behind the printhead, through the paper feed rollers. A rotating knife above the paper feed, slits the paper tape into two slices: one for the plaintext and one for the ciphertext.
Carrying the H-54 HELL H-54 cipher machine (closed) HELL H-54 cipher machine Close-up of the H-54 H-54 with top lid open Interior of the H-54 H-54 with all accessories HELL H-54 (right) aside a Hagelin CX-52 (left)
Bottom view of the H-54 Bottom retaining clip Open paper compartment Close-up of paper reel in the bottom compartment Paper fed through the printer Wheel axle Printer Left side of the CX-52 (left) and H-54 (right)

Immediately after WWII, restrictions were imposed on Germany by the Allied Forces. As a result, Germany was not allowed to develop cipher machines in the years following WWII. As the new German Army, the Bundeswehr needed good cipher machines, HELL was asked to build them under license from the Hagelin Company in Switzerland.

Like the Hagelin CX-52, the HELL-54 is a so-called pin-and-lug machine, using 6 cipher (pin) wheels as its cryptographic engine. Each wheel has a different number of steps (and hence pins) to complete a full revolution, all of which are co-primes in order to obtain the maximum possible cryptographic period. Each wheel carries a number that corresponds to the number of steps. Unlike the CX-52, that was supplied with 12 different cipher wheels, the H-54 came with a selection of just six of these wheels, with the following number of steps:

29 31 37 41 43 47

Each of the six wheels is mounted on a metal base plate with a cog-wheel and the corresponding number engraved. The wheels should only be mounted on the matching base plates. The base plates can be removed from the machine by pulling out the main axle from the right. They can then be inserted again in 120 different orders (6 x 5 x 4).

The toolbox of the machine contains six spare pin wheels with the same number of steps as listed above. This allowed a new set of pin wheels to be prepaired for next day's cryptographic key well in advance. When the key was changed at midnight, there would be a minimum down-time. The machine was interoperable with the Hagelin CX-52, but only if the six cipher wheels listed above were used. The CX-52 was sometimes with 12 different cipher wheels, of which only these six matched the H-54. The handheld HELL STG-61 was supplied with the same wheelset.

HELL H-43 (left) and the original Hagelin CX-52 (right)

Improvements over the CX-52
The H-54 was built under license from the Hagelin Company in Zug (Switzerland) and was functionally identical to the Hagelin CX-52. Nevertheless, the H-54 has some practical improvements over the CX-52 design. The most important ones are listed here:
  • Transport handle
    The transport handle at the right is more robust and is in a different position. Furthermore, it makes full revolutions, whereas the handle of the CX-52 only makes an up/down movement. The handle can be rotated backwards freely without affecting the mechanism. The (black) knob of the handle can be folded 'inside' the handle, only when the handle it locked in its storage position.

  • Complementary slider
    Above the cipher wheels is a narrow window with a ruler (marked 1 to 8). Behind this window is a movable tab that can be clicked into any of the 8 positions.

  • Robust housing
    the outer body of the cipher machine and the top lid that covers the wheels, are made of slightly thicker aluminium, making the machine more robust in day-to-day military use.

  • Improved case
    The storage cased is improved over the original Hagelin design. It now contains an extra storage compartment in the top section of the lid, whilst in the original design, some tools were stored inside the top lid.

  • Removable alphabet ring
    The alphabet ring at the front left can easily be swapped for an alternatively ordered alphabet by removing the plastic ring. The ring is held in place by means of a small piece of feathering steel at the left. On the original CX-52, the letter ring consisted of separate letter-inserts that had to be placed/swapped individually.

  • Print wheel retaining clip
    By pulling the print wheel knob at the left side of the machine, the offset between the two print heads (i.e. the offset between the input and the output alphabet) can be adjusted. To prevent this from happening accidently, the knob of the H-54 has been given a plastic rig that is blocked by a retaining lever mounted below it. In order to adjust the alphabet offset, the lever should be pushed down before pulling-out the knob.

  • Removable dust cover
    In order to mount the H-54 on the B-62 keyboard, the dust cover (i.e. the toolbox) might have to be removed from the machine. On the original CX-52 this was done by unscrewing the rear hinge of the cover. On the H-54 however, a slide-on cover has been used. It is held in place by means of a simple retaining clip behind the machine.

  • Simplified case lock
    The original CX-52 was issued with either a cylinder lock or a complex cross lock at the right side. The case could only be opened with the appropriate key, whilst the cover over the wheels was locked with an even more secret key. On the H-54 only simple locks are used, as the machine was considered to be issued only to qualified personnel. The lock at the right has been replaced by a simple one that can be operated with a screwdriver.

Transport handle Slide ruler above the cipher wheels Close-up of the H-54 Storage compartment for tools and accessories Removable alphabet ring Print wheel retaining clip Removable dust cover Simplified case lock

One of the nicest improvements of the H-54 over the original Hagelin CX-52 is the addition of a clever storage compartment in the top section of the dust cover. An extra lock, just above the leather carrying strap gives access to this compartment. Press the knob to open the top lid. If it doesn't open, you may have to disengage the safety lock inside the dust cover first.
The image on the right shows the H-54 cipher machine with its dust cover closed and its toolbox open. Some parts are stored on top of the machine, whilst the remaining parts are stored inside the case lid. A checklist (in the German language) inside the top lid shows which parts and accessories should be present.

The lower part contains a spare paper reel at the center. To its left are two cylinders: one with spare ink rollers and another one with spare pins (missing here). At the far left are 6 spare fuses (300 mA and 2A) for the B-62 keyboard.
H-54 with open toolbox

At the front left is a spare print wheel (missing from our set) and at the far right is a pin-wheel resetting tool (missing here). Behind the front edge is a spare transparent plastic alphabet ring. Inside the top lid are six spare pin-wheels, a pair of tweezers, a pin setting tool, a brush and a piece of cloth. The pin-wheels are held in place by a hinged panel that can swing to the left.
Top lid lock Toolbox safety lock H-54 with open toolbox H-54 with all accessories Spare print head Spare fuses (for B-62) and spare ink rollers Spare pin wheels Tweezers and pin-setting tool

B-62 Keyboard
Like the Hagelin CX-52, the HELL H-54 could be enhanced with a large motor-driven keyboard, which effectively converts the mechanical cipher machine into a fully automatic electro-mechanical one. For this, HELL built the B-62 keyboard extension, which was a copy of the Hagelin B-62, albeit in Bundeswehr green colour. It is fully interoperable with a Hagelin B-62, which in turn was the fully transistorized successor to the earlier Hagelin B-52 keyboard.
The B-62 consists of a large base in which the motor and the various electronic and mechanical parts are housed. At the right are the power switch, the fuses and the connection to the AC mains (110 or 220V) or an external 24V DC source. The mains cable is fitted permanently.

At the front right is a 26-button keyboard with the letters A-Z in the German arrangment (QWERTZ). All keys are dark brown except for the top left one which is red. At the right end of the middle row is a blind key that is not functional. It is a spare one that is bolted to the top panel.
H-43 ci[her machine mounted on top of a B-62 keyboard

Behind the keyboard is a horizontal bay in which the H-43 machine can be installed. It should be fitted in such a way that the meachanical drives at the left line up with the axles that stick out at the left side of the H-43. This way the transport mechanism of the H-43 can be driven, as well as the letter wheel (at the front left of the machine). A small metal lever can be used to toggle between ciphering and deciphering (in German: (V) Verschlüsseln and (E) Entschlüsseln).
At the front left is a large 'blob' with a hinged panel that swings open upwards. Behind the panel are four rows of 13 banana-type sockets. The 26 sockets in the outer two rows are red and are marked with the letters of the alphabet (A-Z), whilst the 26 sockets of inner rows are black. The black sockets are also marked with the full alphabet (A-Z). 26 patch cables are used to connect the red sockets to the black ones.

The patch board added an extra layer of permutations to the cipher algorithm and is the equivalent of a transposed alphabet ring.
Close-up of the plugboard

The area behind the plugboard, houses most of the electro-mechanical parts of the B-62. It can be accessed by removing the cover from the left side. The bottom side of the unit contains the transformer, the motor, the keyboard and the electronic circuits. The latter consists of two PCBs with one of the first generations of transistors on them (AC153). Considering the time it was built (between 1962 and 1965) the quality of the printed circuit board (PCB) is extremely high.
HELL B-62 keyboard for the H-54 H-43 ci[her machine mounted on top of a B-62 keyboard B-62 keyboard with H-54 cipher machine and opened plugboard B-62 with open plugboard Close-up of the plugboard Electro-mechanical parts inside the 'blob' at the left side of the B-62 keyboard Bottom view of the interior of the B-62 keyboard PCB with electronics

A trip down memory lane
Jim Meyer recalls...

During his time in the German Bundeswehr, Jim Meyer was assigned to the German Army Signals Corps, where he was trained on the HELL H-54 early in 1962 [1]. Because of the way the transport arm of the H-54 works, the machine received the nickname Kaffee-Mühle (coffee-grinder). Later that year his unit was asked to test the new B-62 keyboards under a variety of conditions.

For the test, soldiers with full NATO sucurity clearence had been selected. There were four complete systems, each consisting of a H-54 and a B-62, that were tested for a full week, 24-hour per day in 3 eight-hour shifts. Each operator would test the machine for 8 full hours under hot and cold conditions, then sleep for 8 hours, then perform another 8-hour test and so on. The machine would be operated non-stop for 24 hours by pressing random keys on the keyboard.

The tests were carried out south of Munich at Lake Starnberg (near the Alps) in the shelter (Kofferaufbau) at the back of a military MAN truck that was parked in front of the building, guarded by two heavily armed soldiers. Testing the machines under cold conditions was no problem, as the test was carried out mid-winter and the outside temperature was -15 °C

For the hot condition tests, two large professional hair dryers were used. They were aimed at the machine until the metal could no longer be touched. This process was repeated for 24 hours: one hour cold and one hour hot. Needless to say that both the H-43 and the B-62 passed all tests with flying colours and that it improved the operational speed of the H-43 by a factor of 10.
  1. Helmut 'Jim' Meyer, HS0ZHK, My way to Ham - Radio and beyond
    Website QRZ.COM. Personal correspondence. Retrieved April 2013.

  2. HELL, Beschreibung des Spruchschlüsselgerätes H
    H-43 User Manual (German). 44 pages. Date unknown. 5810-12-120-8632.

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