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Hagelin CX-52
Pin-and-lug cipher machine with irregular stepping

CX-52 was a mechanical pin-and-lug cipher machine, developed around 1952 by the Swede Boris Hagelin and manufactured first by AB Cryptoteknik in Stockholm (Sweden) and later by Crypto AG in Zug (Switzerland). It was intended as a replacement for earlier machines, like the C-446 and M-209. CX-52 has an irregular movement of the cipher wheels, and is considered the more secure version of the C-52. At the time, CX-52 was virtually unbreakable by the NSA.

Compared to earlier designs, it offers several improvements. It has six interchangeable cipher wheels that can be removed easily by pulling out the main spindle from the right side. All wheels have a different number of divisions, or steps, or segments, which ideally should be coprimes.

The wheels were normally black, as shown in the image on the right. In some cases, users had six additional wheels, which were usually white. Of the total set of 12 wheels, six were placed in the machine – subject to the current KEY – whilst the remaining six were stowed in a metal container.
  
CX-52 with open lid

The machine was available in a civil (grey) and military (green) variant, which were functionally identical. When used properly, the CX-52 was highly secure and very difficult to break by the US National Security Agency (NSA). It was possible however, to set it up in such a way that it had a short cycle (period), in which case it was easy to break. This was fixed in the CX-52M, which was modified by NSA cryptomathematician Peter Jenks, to always produce a long cycle, albeit one that was predictable by NSA. It looked safe from the outside, but was in fact weaker than before [5].

For customers who did not move from the CX-52 to the CX-52M, special manuals were available to learn them how to make 'proper' (secure) use of the machine. By supplying different manuals to different customers, this too became a way of manipulating the strength in favour of the NSA.

For use in base stations, the CX-52 could be expanded with a B-52 or B-62 keyboard unit, in which case the function of the advance lever was taken over by a motor. This greatly improved the throughput of the machine. The combination of CX-52 and a B-52/B-62 was known as BCX-52.
  
CX-52/RT with key tape

The machine was also available in a Random-Tape (RT) version (shown above), in which case the cipher wheels had been replaced by a 5-level tape reader. As these machines are based on the One-Time Tape (OTT) principle, they are theoretically unbreakable. For this reason they were only advertised and sold to friendly nations 1 like NATO countries, Switzerland and Sweden. This was part of a secret deal between Hagelin and NSA, today known as The Gentleman's Agreement [1].

Despite a slow start – mainly caused by the implementation of the The Gentleman's Agreement – the machine became very popular. By the mid-1950s, it was already used by 50 countries [3]. In 1970, the CX-52 was succeeded by the electronic H-460. Nevertheless, many of them were kept as backups during the Cold War, well into the 1980s — in Belgium even well into the 1990s. 2

  1. As NSA refused to tell Hagelin which countries were on their target list, Hagelin assumed he could also sell these machines to South American countries, like Argentina and Brasil. When in 1960, the CIA Licencing Agreement came into effect, Hagelin learned that this was not the case [5].
  2. During the Cold War, mechanical cipher machines were kept as backups, as they are less prone to an electromagnetic pulse (EMP), and would therefore survive a nuclear attack.

CX-52 ready for use
CX-52 with open lid
CX-52 with open lid
CX-52 front view
Printer
Wheels removed from the machine
Removing the cipher wheels
B-621 with CX-52/RT
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CX-52 ready for use
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CX-52 with open lid
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CX-52 with open lid
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CX-52 front view
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Printer
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Wheels removed from the machine
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Removing the cipher wheels
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B-621 with CX-52/RT

Features
The diagram below provides a quick overview of the many controls and settings of the CX-52. Note that many versions and variants exist, and that not all controls are available on all versions. The machine is shown here with it cover open, revealing the six removable cipher wheels (at the front) and the revolving cage with sideways movable (sliding) bars behind them. At the front left is a strip printer with a settable letter wheel at the top. It is used as the input/output device.

Click to see more

Setting the cryptographic KEY, involves setting the pins on each of the wheels, and inserting the selected wheels in the machine in a given order, as instructed by the (daily) KEY sheet. Next, the MODE selector at the left side is set to C – for ciphering – or D for deciphering. A message is enciphered letter-by-letter, by setting the letter selection disc at the front left to the input letter, and operating the advance lever at the right. The input and output letter is then printed on the paper strip at the left. A built-in rotating knife, automatically cuts the paper strip in two halves.

 Operating principle

With open printer cover
Print head
Mechanism
Various CX-52 models
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With open printer cover
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Print head
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Mechanism
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Various CX-52 models

Models
  • CX-52
    Standard (initial) version of the machine. Very secure when used properly, and extremely difficult to break by NSA at the time. It defeated the existing methods for solving Hagelin ciphers. NSA tried to persuade Hagelin not to sell these machines to denied countries, but refused to share the denied-list with him, as NSA didn't want to reveal its targets [5].

    It was possible to setup this machine in such as way that it produced a short cycle, as a result of which it became easier to break. Unwitting users could easily select a weak key. For this reason, the CX-52 was never adopted for use by the US Army and by NATO.

  • CX-52M
    This version was marketed by Crypto AG as the improved – more secure – version of the CX-52, which always produced a long cycle (period). The modification was developed by Peter Jenks at NSA. In reality, the cycle was predictable, and allowed NSA to break it [5].

  • CX-52/RT
    This is the most secure version of the CX-52, in which the cipher wheels are replaced by a 5-level reader for punched paper tape. It is also known as the RT/CX or OTT or Mixer. It was only advertised and sold to friendly nations, such as the NATO countries, Switzerland and Sweden. When used properly, this machine is theoretically unbreakable, as it is based on the One-Time Pad (OTP) system.

    In 1960, Hagelin sold a large batch of CX-52/RT machines to Brasil, but this met with fierce opposition from NSA/CIA, as Brasil was on the proscribed list (the list of countries to which secure machine had to be denied) — which Hagelin didn't have. Hagelin acted immediately and persuaded the Brasilians to swap the RT-machines for the (exploitable) CX-52-M-27. He also stopped advertising the RT-model below the Mexican border [5].
Secret designators
According to the The Gentleman's Agreement — it controlled which machines could be sold to whom — Hagelin had secretly designated a range of version and variant numbers, which were not printed on the machine's label. He identified the CX-52 as a Class-2 machine, which was more advanced than the C-52 — a Class-1 machine. The following secret designators are known:

  • CX-52a
    This model is supplied with Standard A slide bars, which produce irregular or varying angular displacements of the key wheels, each wheel advancing 0, 1, 2, 3, 4 or 5 steps on each operation. It was supplied with pin-wheels 29, 31, 37, 41, 43 and 47. This is the default and most secure version of the machine.  Example

  • CX-52b
    This model is supplied with Standard B slide bars, which produce regular or fixed anglular displacements of the key wheels, all advancing the same number of steps, but the number of steps may be any one from 1 to 32. It was supplied with pin-wheels 29, 31, 37, 41, 42 and 47. It is weaker than the a-variant.

  • CX-52c
    This model is supplied with Standard C slide bars, which makes it backwards compatible with the older types of C-machines, such as the M-209, the C-446 and a certain version of the C-52. It was supplied with pin-wheels 25, 26, 46, 42, 38 and 34, which had to be installed in that order. It is the weakest of the models.  Example

  • CX-52ak
    This is basicially a CX-52a, that is enhanced with the so-called Complementary feature (German: Komplementär), also known as the Hüttenhain feature. 1

  • CX-52bk
    This is a CX-52b, enhanced with the Hüttenhain feature. 1 This variant was built by HELL (under licence from Hagelin) for the German and Austrian market, for which HELL had an exclusive contract. It is the only version that was approved by Dr. Erich Hüttenhain 1 for use by the German Bundeswehr (Army), where it was known as the HELL H-54.

  • CX-52ck
    CX-52c with Hüttenhain feature. 1

  • CX-52/10
    This is a 10-digit numbers-only variant of the CX-52. These machines can be of the a, b or c type and can optionally have the complementary feature. For example: CX-52ak/10.

  • CX-52/30
    This is a 30 character version of the CX-52, 2 suitable for alternative languages – like Arabic and Russian – but also for users who required additional symbols.  Example

  • CX-52/RT
    This is the Random Tape variant of the machine, also known as One-Time Tape (OTT). It is the most secure version of the CX-52 and was only offered to friendly nations.
  1. During WWII, Dr. Erich Hüttenhain was the chief cryptologist of the Third Reich. After the war, he was employed by the new German Intelligence Agency, the Organisation Gehlen (OG) — in 1956 renamed to Bundesnachrichtendienst (BND). Until 1970, Hüttenhain was the head of the German cipher authority ZfCh. The idea for the complementary (komplementär) feature was probably borrowed from the wartime German cipher machine Schlüsselgerät 41 (SG-41), developed by Regierungsoberinspektor Fritz Menzer.
  2. In the same vein, a 30-character version of the C-52 was available for the Arab language.

HELL H-54 (CX-52bk) aside a regular CX-52a (right)

Versions and accessories
Standard (civil) version of CX-52
Military version of CX-52
30-character version
CX-52/RT with key tape
OTT
Cut-away version for instruction purposes
HELL H-52 (improved CX-52 clone)
Special version gifted to former users
B-52, B-62 or B-261 keyboard
Additional cipher wheels
Maintenance tools and supplies
Operational Instructions and service manuals
Civil version   CX-52
The basic version of the machine was sold in a grey painted enclosure. It is also known as the civil version, although the military version was identical (apart from the colour).

Note that there are many versions and variants of this machine, with different locks, print heads, reconfigurable letter selection discs and with or without certain features. The version shown here does not have the F/V selector at its left side.

 Details

  
CX-52 with open lid

Military version   CX-52
The image on the right shows a military version of the CX-52. It is identical to the standard (civil) version, but it painted in a military green colour.

The case is locked by means of a cross-lock-and-key, whereas the civil version has a regular cylinder lock. The version shown here has an F/V selector at the left side (towards the rear) which is missing from the civil version shown above.

 Details

  
CX-52 military version - with open lid

30-character version   CX-52/30
This version support 30 character alphabets, such as Arabic and Russian, but also extended Latin alphabets. The one shown here has the standard 26 letters of the Latin alphabet (A-Z) plus four additional markup symbols.

The machine can easily be converted for another language, by swapping the letter ring at the front left and the double head.

 More information
 Details

  
CX-52/30 with open lid

One-Time Tape version   CX-52/RT
By far the most secure model of the CX-52 was the Random Tape (RT) version, commonly known as CX-52/RT or RT/CX. It a One-Time Tape (OTT) machine, or mixer, that is based on the principle of the One-Time Pad (OTP). When used correctly, OTT machines are unbreakable.

This version was only advertised and sold to friendly nations, such as all NATO countries, Switzerland, Sweden and very few others.

 Details

  
CX-52/RT with key tape

Cut-away version
The image on the right shows a modified CX-52, of which part of the body has been removed, so that the inner mechanics are visible.

This item was found on eBay in 2009, and was probably made for instruction purposes, or just for fun. The machine has been repainted in blue hamerite, and the edges of the cut-out sections have been highlighted in red.
  
Cut-away version of CX-52

HELL H-54
In the mid-1950s, the German company HELL was contracted by the German Army — Bundes­wehr — to build this CX-52 clone. At the time, Germany was not allowed to develop its own encryption devices, but building them under licence from a foreign developer was allowed.

The machine was designated H-54. It has has several improvements over the original CX-52, including one that was developed by Dr. Erich Hüttenhain, the head of the German cipher authority ZfCh (and former head of OKW-Chi).

 More information

  
HELL H-54 with open lid

Silver version   CX-52/RT
Over the years, many mechanical Hagelin cipher machines like the CX-52, found their way to the Netherlands, where they were used by the Army, the Air Force, the Navy and the Foreign Office.

In later years, when mechanical cipher machines had been replaced by electronic ones, it became common practice to give former crypto-users or decision makers, a silver-painted Hagelin cipher machine as a retirement present. The one shown here was given as a farewell present to the (then) head of the Dutch cipher authority.

 Details

  
Silver CX-52/RT with open lid

Keyboard   B-52, B-62, B-621
The basic CX-52 is a fully mechanical device, that requires a text to be encrypted letter-by-letter. As this is a very time-consuming task, it was possible to use a special motor-drive with keyboard, that had a bay for the CX-52.

The expansion, or B-unit, was mainly used in base stations and command centres. The design faced many mechanical and electrical problems, as a result of which there are many production variants, designated B-52, B-62, B-621, etc. The combination CX-52/B-52 was known as BCX-52.

  
B-621 keyboard with motor-drive

Additional wheels
Each CX-52 was supplied with six (usually black) cipher wheels, that had 25, 26, 29, 31, 34 and 37 divisions, although other combinations were supplied as well. It could be extended with six further (usually white) cipher wheels, with 38, 41, 42, 43, 46 and 47 divisions respectively.

The additional wheels were stored in a slimline metal container, such as the one shown in the image on the right.
  
Close-up of an additional cipher wheel

Maintenance tools and spares
Each CX-52 came with a set of maintenance tools and spares, such as oil, spare lugs (tabs), spare ink rollers, screwdrivers, tweezers, etc., that were stowed inside the dust cover.

Depending on the exact model and variant, some tools may have been omitted.
  
Tools and supplies

User and service manuals
Each CX-52 came with a blue printed manual in three languages. Note however, that there were different manuals for each variant, customer and/or country, and that some manuals may have been rigged, to prevent the machine from being used properly (i.e. make it breakable).

In addition, there was a wide range of service manuals, parts lists, application notes, leaflets, brochures, etc., some of which are available from the Documentation section below.

 CX-52 documentation

  
C-52 and CX-52 manuals

CX-52 military version
CX-52 military version
CX-52 military version - with open lid
CX-52/RT with key tape
CX-52/RT with key tape
Silver CX-52/RT
Silver CX-52/RT with open lid
Silver CX-52/RT with open lid
Tape reader removed from the machine
B-621 keyboard with motor-drive
B-621 keyboard with motor-drive
B-621 with CX-52/RT
CX-52 (closed) and box with additional cipher wheels
Six additional wheels for CX-52
Additional cipher wheels in metal container
Close-up of an additional cipher wheel
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CX-52 military version
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CX-52 military version
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CX-52 military version - with open lid
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CX-52/RT with key tape
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CX-52/RT with key tape
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Silver CX-52/RT
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Silver CX-52/RT with open lid
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Silver CX-52/RT with open lid
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Tape reader removed from the machine
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B-621 keyboard with motor-drive
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B-621 keyboard with motor-drive
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B-621 with CX-52/RT
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CX-52 (closed) and box with additional cipher wheels
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Six additional wheels for CX-52
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Additional cipher wheels in metal container
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Close-up of an additional cipher wheel

Working
The CX-52 is basically a polyalphabetic substitution cipher, based on the Beaufort Cipher. It is very similar to the Vigenère Cipher, but with the second alphabet in reversed order. At the heart of the machine is a pseudo-random number generator (PRNG), which comprises a revolving drum (cage) with 32 sideways movable bars (slide bars), and six cipher wheels (pin-wheels). It has a twin-head printer which acts as input/output device. After selecting the input letter, the handle is operated to set the PRNG in motion. This causes an angular displacement of the print head.

IPO model (input-processing-output)

Overview
The precise operation of the CX-52 and the many different variants and configurations in which it was available, are clearly described in a paper of 2021 by Bart Wessel [7]. This paper also explains the details between the CX-52 and the simpler C-52. Before going into details about the inner operation of the machine, it is worth explaining a few terms, using the image below as a guide.

Overview of the main parts of the CX-52. For a more detailed description, refer to Bart Wessel's paper [7].

The terminology is often confusing as Hagelin used different expressions over the years, and today's collectors and curators tend to use different ones altogether. The most important parts – highlighted in red in the image above – are listed here, with the known alternatives in brackets:

  1. Print head
    (typewheel unit) (alphabet unit) (print wheels)
  2. Journal plate
    complete assembly with pin-wheel (4) and guide arm (3)
  3. Guide arm
    senses the presence of an active pin on the pin-wheel
  4. Pin-wheel
    (key wheel) (keywheel) (pin disk)
  5. Drum
    (cage) (bar drum)
  6. Bar
    (slide bar) (sideways movable bar)
  7. Cam
    (tooth) cams are used to control wheel stepping and print head rotation
  8. Lug
    (bar lug) lugs are configurable and control displacement of the bars
  9. Locking bar
    (top cradle) locks the guide arms when operating the machine
Pin-wheels
At the front of the machine are 6 removable cipher wheels (pin-wheels), that can be installed in any possible order. Some machines came with an extra set of 6 wheels, so that users could select 6 from the total set of 12 wheels. Each wheel has a different number of divisions, or faces, which ideally do not share a common factor to ensure the maximum possible cipher period. Depending on the model, a selection of 6 wheels was supplied with the machine, taken from the full set:

25 26 29 31 34 37 38 41 42 43 46 47

Each cipher wheel is protruded by a number of configurable pins, that is equal to the number of divisions of that wheel. When seen from the front, these pins can be shifted to the left (to make them inactive) or to the right (active). These states are also known as '0' (inactive) and '1' (active).

Click to see more

For this reason, a cipher wheel is also known as a pin-wheel. It is mounted onto a vertical metal journal plate and can be rotated freely. Each segment is numbered on the front face and the right side from 01 onwards. The total number of divisions is imprinted on the right side of the wheel and on both sides of the journal plate. A large cog-wheel is attached to the left side of the pin-wheel. It is driven by a small cog-wheel, that in turn can be driven by the cams of the slide bars.

Aside the small cog-wheel is a spring-loaded locking pawl, that prevents the pin-wheel from stepping when it is not actively driven by the small cog-wheel. Like the small cog-wheel, it is controlled by the cams of the slide bars, but never simultaneously with the cog-wheel, as that would cause the machine to block. The spring-loaded guide arm – at the right side of the pin-wheel – has a sensing tip that can slip into the space of an inactive pin. At the start of each cipherment cycle, the positions of all guide arms are locked by the U-shaped locking bar.

Slide bars
Towards the rear of the machine is a revolving cylindrical drum (cage) with 32 sideways movable bars. When operating the machine with the advance lever at the right, the drum makes one full revolution. Each bar has a series of cams (teeth) along one of its sides. In addition, most bars have notches on both sides to accomodate removable lugs. The cams control the stepping of the pin-wheels, whilst the lugs and the guide arms control the sideways displacement of the bar.


At the left end of each bar are two cams that control the stepping of the print head. When the bar is displaced (i.e. fully to the left), the leftmost cam extends from the drum. The drawing above shows the fictive bar number 77, on which all features are present. 1 Read this bar as follows:


This drawing shows the space that is taken by each of the six wheels in red. The darker red vertical lines represent the six support discs inside the drum. It is now possible to identify the cam types, identified by Hagelin as A, B, C and 0. The printer cams at the left are known as K.


The diagram above shows each cam, when ignoring the notches for the lugs and limiting their size to the space of a single wheel. There are four different cam types. Depending on the position of the slide bar – displaced or non-displaced – the cams have the following functions:

  • Cam A
    Advance the pin-wheel only when the bar is displaced
  • Cam B
    Advance the pin-wheel only when the bar is not displaced
  • Cam C
    Always advance the pin-wheel
  • Cam 0
    Never advance the pin-wheel

  • Cam K
    Advance the print head when the bar is displaced
Each bar has a different combination of cams and is identified by a number that is imprinted anywhere on one of its faces. Although most bars can be fitted with lugs, there are bars that are not luggable, such as bar number 16 in the diagram below. Such bars have no notches for the lugs, and can therefore never be displaced (and hence never cause the print head to advance).


The regular bars discussed above, all have a so-called K-cam at the left end. This K-cam causes the print head to make a single step when the bar is displaced (i.e. shifted to the left). According to Bart Wessel in [7], there are two further bar types: one that never causes the printer to advance (the K-cam is missing), and one that has an inverted effect (K̅). The latter advances the print head when it is not displaced. It has a single tooth positioned in between the two regular ones:



 Overview of all known bars

  1. Note that bar 77 is a fictive bar, on which all combinations of cams are present. This bar does not exist in real life. It is also used as an example in Bart Wessels paper [7].

Stepping
The drawing below shows how the pin-wheels – and indirectly the print head – are advanced. The image shows bar 77 at several positions during the rotation of the drum 1 as seen from the top of the machine. At the bottom are the six pin-wheels, of which the small advancing cog-wheel is shown in red, and the locking pawl (that prevents the wheel from advancing) is shown in blue.

When the bar arrives at the front of the machine, its cams interact either with the (red) cog-wheel or with the (blue) locking pawl (never both). The image shows the situation when the bar is not displaced. Move the mouse over the image to see the effect of the cams on the displaced bar.

Slide bar with cams — move the mouse over the image to see the bar displacement

A bar is displaced when it has a lug that is engaged by a guide arm that is locked in place by the locking bar. In the image above, the guide arm of the rightmost pin-wheel is shown, in unlocked position. 2 Move the mouse over the image to see what happens when the guide is locked and engages with the lug. The bar in the above example shows the effect of all four possible cam types – identified by Hagelin as 0, A, B, and C – on a displaced and non- displaced bar.

  1. Note that bar 77 is a fictive bar, on which all combinations of cams are present. This bar does not exist in real life. It is also used as an example in Bart Wessels paper [7].
  2. The guide arms of the other pin-wheels are omitted for clarity.

Printer
At the left side of the machine is a printer which acts as the input/output device. It has a double print head, of which the leftmost letter ring contains the alphabet in the regular order, whilst the rightmost ring holds the alphabet in reversed order. When ciphering, the input letter is selected with a knob on the left. It is turned until the dial at the front points to the desired input letter.

Depending on the model/version/variant, different print head types were supplied. There are print heads with fixed or re-arrangeable letters, and there are units with a fixed or variable offset between the input and output print head. The following variations in print heads are known:

Re-arrangeable print head
Each of the heads has 26 removable inserts — one for each letter of the alphabet. This allows the alphabet to be scrambled freely. It is important though, that the secondary head is scrambled in the same way but in reverse order, as otherwise the machine would lose its reciprocity. Swapping the letters of the print heads is only useful when the letters of the indicator disc (dial) can also be swapped. The latter is not always the case and depends on the version/variant of the machine.

The double print head of the CX-52, with swappable letters

If the order of the letters on the output print head is not the reverse of the order on the input head, the machine is no longer reciprocal. This can be solved by using a second print head which is the 'mirror' of the first one, and swapping them when switching from ciphering to deciphering.

As the print head contains only the letters of the alphabet and no SPACE, it was common practice to trade one of the letters for the SPACE character. This was done by setting an index pin – fitted at the right side of the rightmost print head – at the required letter. In this example it is set to the letter X, which is the least frequently used letter in most languages. Should the letter X appear in the plaintext, it could easily be swapped for one or two other letters. Here are some examples of commonly used SPACE characters and their replacements:

  • J
    I
    e.g. English
  • W
    VV
    e.g. Spanish, Italian
  • X
    KS
    e.g. German
  • Z
    TS
    e.g. English, German
  • K
    CC
    e.g. French
F/V feature
When present, the F/V feature allows the user to switch between a fixed offset of the print heads (F) or a variable one (V). In the latter case the two print heads are detached at the start of the ciphering cycle, and are reconnected once the output letter is printed. This means that for each cycle, a new offset of the two print heads will be used. The following configurations are known:

  1. No F/V feature
  2. Externally controllable F/V feature (F/V knob on the left side)
  3. Internally controllable F/V feature (requires the left side panel to be removed)
On some machines, the F/V feature is externally controllable by means of an extra knob that is located towards the rear of the left side of the machine. It has two possible settings, marked (F) and (V). On some machines, the F/V feature was present, but was not visible from the outside. In that case, the knob was hidden behind the left side panel. In machines without the F/V feature, a (fake) short metal stub was usually mounted in its place, and the detaching bracket was missing from the printer compartment. To our knowledge, the F/V feature was not available on the C-52.

Indicator   dial
When cipherig, the input letter is selected by rotating the knob at the left side of the machine (i.e. the print head) until the pointer at the front of the machine points to the desired letter on the letter ring. This letter ring is known as the indicator or dial. It is usually engraved with the letters of the alphabet, but may also consist of small individual circular inserts, in which case they can be swapped. This is useful when re-arranging the letters of the print heads (in the same order).

 Read Bart Wessel's full paper

CX-52 parts
Right and left side of a pin-wheel
Guide arm and pins
Driving cogwheel and locking pawl
Driving cogwheel and locking pawl
Front view
Print head
Double print head, seen from the right
Double print head, seen from the front
Double print head, seen from the left
Double print head - close-up
Left side of a CX-52. The F/V knob is at the bottom left.
Left side of the machines. The F/V selector is at the bottom left.
Print head installed in the printer
Cradle for the print head. The curved bracket is part of the F/V feature
Print head, showing the pinter that indicates the SPACE character
Example of a CX-52 in which the F/V feature is hidden behind the left side panel
Mechanism at the left side, visible after removing the left side panel.
F/V feature missing
Detached print heads at the start of the cipher cycle (F/V feature set to V)
Print heads reconnected at the end of the cipher cycle
Detached print heads
Letter-ring with re-arrangeable letters
Recessed screw that holds the letter ring in place
Metal container with spare letters for the letter ring
Spare letters for the letter ring, stowed in a metal tube.
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CX-52 parts
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Right and left side of a pin-wheel
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Guide arm and pins
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Driving cogwheel and locking pawl
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Driving cogwheel and locking pawl
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Front view
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Print head
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Double print head, seen from the right
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Double print head, seen from the front
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Double print head, seen from the left
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Double print head - close-up
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Left side of a CX-52. The F/V knob is at the bottom left.
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Left side of the machines. The F/V selector is at the bottom left.
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Print head installed in the printer
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Cradle for the print head. The curved bracket is part of the F/V feature
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Print head, showing the pinter that indicates the SPACE character
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Example of a CX-52 in which the F/V feature is hidden behind the left side panel
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Mechanism at the left side, visible after removing the left side panel.
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F/V feature missing
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Detached print heads at the start of the cipher cycle (F/V feature set to V)
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Print heads reconnected at the end of the cipher cycle
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Detached print heads
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Letter-ring with re-arrangeable letters
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Recessed screw that holds the letter ring in place
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Metal container with spare letters for the letter ring
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Spare letters for the letter ring, stowed in a metal tube.

BC-52 Simulator for Windows
Belgian crypto-researcher Dirk Rijmenants, has created a very realistic simulation of the BC-52 that runs on the Windows™ operating system. The BC-52 is actually a C-52 that is seated on a B-52 keyboard, hence the name BC-52. The software allows you to select between C-52 and CX-52 simulation, and customize the machine in various ways. Full instructions are included with the program.

The image on the right shows a screenshot of the BC-52 simulator running on Windows. It can also be used on Linux (WINE) and Mac (Parallels).

 Download (off-site)

  
Click here to download Dirk Rijmentants' BC-52 Simulator for Windows (off-site)


Sound
Below is a sound clip of a CX-52 in operation, recorded at Crypto Museum on11 April 2021.


Documentation
  1. The Hagelin Cryptographer, Type CX-52
    User Manual in English, French and German. 36 pages.
    D-035. Crypto AG, 1 January 1962.

  2. The Hagelin Cryptographer, Type CX-52 (photographs)
    Photographs belonging to the above manual [A]. 4 pages.
    Crypto AG. 16 January 1951.

  3. Instructions for the tape controlled cryptographer CX/RT
    User Manual for the CX-52 with random tape (RT) (English). 7 pages.
    No. 3165-a. Crypto AG (OST/iz), June 1968.

  4. Spare parts catalogue CX-52 (No 21101 etc)
    Spare parts list with instructions in English, French and German. 35 pages.
    L-061 (S/N 61851). Crypto AG. 1 January 1962.

  5. RT/CX One Time Tape auxiliary device
    CX-52/RT sales brochure (English). 3 pages.
    No. 3093 A. Crypto AG (Sn/hf), December 1958.

  6. Appareillage pour Chiffrement à Bandes Perforées
    Instructions for CX-52/RT (RT/CX), B-621 and PEB-61 (French).
    No. 2268. Crypto AG, Oskar Sturzinger. February 1969. 5 pages.

  7. Die Klaviatur B-621 (B-62)
    B-621 (B-62) keyboard attachment for CX-52 (German). 14 pages (with schematics).
    No. 1188a. Crypto AG, Oskar Sturzinger. June 1968.

  8. CX-52 Condensed Instructions
    No. 3035b. Crypto AG, BH. November 1957.

  9. Description of Cryptographers 'Hagelin' Type CX-52
    No. 3027. Crypto AG, Oskar Stürzinger, August 1956.

  10. CX-52 Service Instructions and Maintenance for Ciphering Machines Type CX-52
    No. 3099. Crypto AG, BH, January 1959.

  11. Spare parts catalogue for Hagelin Ciphering Machine Type CX-52
    No. L-013. Crypto AG, May 1956.

  12. Cryptographer type CX-52 - Specification
    No. I-3006c. Crypto AG, Oskar Stürzinger, November 1957.

  13. Service Instructions for keyboard unit B-52
    No. E-3121a. Crypto AG, Oskar Stürzinger, 12 November 1956 — July 1961.

  14. Ersatzteilkatalog (B-52) (spare parts catalogue)
    No. L-027. Crypto AG, 10 October 1957.

  15. Keyboard attachment unit type B-52
    No. 3052a. Crypto AG, Sn, January 1958.

  16. C-52 Trouble Shooting
    No. 3225a. Crypto AG, date unknown.

  17. Usage of Hagelin cryptographer CX-52
    No. <unknown>. 25 November 1964.

  18. Description Technique des Cryptographes Type CX-52
    No. 2027. Crypto AG (BH.Sn), February 1955.

  19. Bedienungsanweisung für das Gerät 'CR-2' (CX-52/RT)
    ZB6, BACR68, S/N 533. Bundeswehr (Germany), 1968.

  20. L'emploi de Bandes Aléatoires ... des Machines à Chiffrer C4 et CX-52
    No. 2084-a. Crypto AG (BH/iz), February 1969.(in French langage).
References
  1. Crypto Museum, The Gentleman's Agreement
    30 July 2015.

  2. Deavours and Kruth, Machine Cryptography and Modern Cryptanalysis
    ISBN 0-89006-161-0. 1985, p. 197.

  3. Boris Hagelin, Die Geschichte der Hagelin-Cryptos
    Original manuscript by Boris Hagelin in German language. Zug, Fall 1979. 1

  4. Wikipedia, Coprime integers
    Retrieved February 2020.

  5. Crypto Museum, Operation RUBICON
    February 2020.

  6. Klaus Kopacz & Paul Reuvers, Schlüsselgerät 41
    Crypto Museum, 6 February 2021.  Info

  7. Bart Wessel, The Hagelin Cryptographers C-52 and CX-52
    Crypto Museum, 24 February 2021.  Info
  1. This story was later translated by Boris Hagelin into English. It can be downloaded here.

Further information
A selection of CX-52 variants

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Crypto Museum. Created: Tuesday 04 August 2009. Last changed: Sunday, 11 April 2021 - 16:54 CET.
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