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Hagelin CRM-008   HC-230 / HC-235
Two-dimensional voice scrambler · CRYPTOCOM

CRM-008 is a two-dimensional voice scrambler, also known as a Frequency and Time Domain Voice Scrambler (F/T), introduced in 1975 by Crypto AG (Hagelin) in Zug (Switzerland) [1]. The device is part of the CRYPTOCOM family of secure speech products, and uses a cryptographic algorithm that was developed by the German cipher authority Zentralstelle für das Chiffrierwesen (ZfCh). In some versions, the algorithm has an exploitable weakness, also known as a backdoor.

The device – previously known as the CV-008 – came in two versions: civil and military, each of which were available in a number of variants. The models were later re-designated HC-230 (civil) and HC-235 (military). The image on the right shows the military version, which was housed in a ruggedised aluminium enclosure.

The device was intended for secure speech over regular analogue voice circuits, such as tele­phone lines and narrowband HF radio channels, that were unsuitable for true digital encryption devices, due to the limited bandwith available.
  
HC-235 voice scrambler in tilted setup

Compared to other voice scramblers of the era — most of which were simple frequency-domain only scramblers (inverters), or time-domain only scramblers (rolling code) — the CRM-008 (HC-230) has the advantage that it scrambles both in the time and frequency domain simultaneously, although the latter is restricted to just two frequency bands, known as low and high (or A and B).

CRM-008 (HC-230/235) was introduced in 1975, as a complementary product to the wideband CSE-280 voice encryptor, that is housed in a nearly identical enclosure (but which is a true digital encryption device). The
cryptologic
of both products was developed by ZfCh, in such a way that it was readable 1 by Western intelligence services. One of the known customers of the device was the Argentine Navy, who used it during the Falklands War of 1982 [2]. The device was succeeded in the early 1980s, by the much smaller HC-250. Note that all scramblers are inherently insecure.

  1. The term readable means that the algorithm could be broken by ZfCh. Also known as friendly or insecure or exploitable. In contrast: algorithms that are not breakable by ZfCh, are called unfriendly or unreadable.

HC-235 voice scrambler in tilted setup Crypto AG HC-235 voice scramber With open keypad HC-235 front panel Connections at the front panel Display and MODE selector 12-button keypad With handset off-hook (note the PTT switch)
A
×
A
1 / 8
HC-235 voice scrambler in tilted setup
A
2 / 8
Crypto AG HC-235 voice scramber
A
3 / 8
With open keypad
A
4 / 8
HC-235 front panel
A
5 / 8
Connections at the front panel
A
6 / 8
Display and MODE selector
A
7 / 8
12-button keypad
A
8 / 8
With handset off-hook (note the PTT switch)

Features
All controls and connections – with the exception of the power input – are located at the front panel. All connections are via (expensive) LEMO plugs. The device is powered by a DC voltage between 10 and 30V, which should be applied to the 4-pin LEMO socket at the rear. This can be supplied by the battery of a car (12V) or truck (24V), or by an external power supply unit (
PSU
).


The front panel can be divided into three sections: (1) the connections to the outside world – located at the left – the MODE selectors and the display at the centre, and a 12-button keypad for entering the cryptographic key – protected by a plastic door – at the right. In case of emergency, the RED push-button (under one of the plastic caps) should be pressed to purge the keys.

Frontal view HC-235 front panel Connections at the front panel Display and MODE selector 12-button keypad Power cable
B
×
B
1 / 6
Frontal view
B
2 / 6
HC-235 front panel
B
3 / 6
Connections at the front panel
B
4 / 6
Display and MODE selector
B
5 / 6
12-button keypad
B
6 / 6
Power cable

Versions
  • CRM-008-001
    Mobile version powered by 10 to 30V DC and connected to the outside world via with a 4-wire audio interface. The device featured here is of this type.

  • CRM-008-002
    This version appears to be physically identical to the CRM-008-001, so it was probably a later hardware variant, or a country-specific variant. Previously known as CV-008.

  • CRM-008-007
    Desktop version with built-in AC power supply unit and telephone adapter circuitry for connection to standard 2-wire PSTN lines. This unit is higher than the mobile version.

  • HC-230
    Desktop version. Believed to be a later designator of the CRM-008-007.

  • HC-235
    Military variant in ruggedised enclosure. Believed to be a later designator of the CRM-008-001 and/or CRM-008-002. Some of the devices featured here, are of this type.
Mode of operation
Frequency mode
  1. Static frequency inversion
  2. Frequency inversion in 4/80 ms intervals
  3. Frequency inversion in n × 80 ms (n≥1)
Cryptographic key
The cryptographic key, or just KEY, consists of 32 digits that are entered on the numeric keypad (behind the plastic lid on the right), as 8 groups of 4 digits each. Each group can be entered individually without altering the rest, by preceeding it with the (mandatory) group number. When entering key digits, the #-key is used to enter the group. The ✱-key is used to cancel the input.


To enter a key, set the MODE-selector on the front panel to KEY. Enter the group number, followed by the four digits of the group, and finish with the #-key (enter). The groups can be entered in any order. If you make a mistake, press ✱ and start again with the group number. When all 8 groups are entered, return the MODE-selector to P (plain) or C (crypto) again.

When the device is switched OFF, the KEY is retained by a battery-powered memory (
SRAM
). 1 In case of an emergency, the KEY can be deleted immedately, by pressing the ZEROISE button (behind a plastic cap on the front panel). This is also possible when the device is switched OFF.

  1. Note that this battery will be exhausted by now. In fact, it is advised to remove it as soon as possible, as it might start leaking when attempting to recharge it, which could lead to permanent damage.

History
The CRM-008 was developed in the early 1970s, at a time when Crypto AG was owned by the German Bundesnachrichtendienst (BND) and the American Central Intelligence Agency (CIA). In order to make the devices readable for their codebreaking services — the German Zentralstelle für das Chiffrierwesen (ZfCh) and the US National Security Agency (NSA) respectively — ZfCH had implement a cryptographic algorithm that had an exploitable weakness, or backdoor [3].

The device was widely used on analogue voice-grade circuits which – due to their narrowband nature – were unsuitable for true encryption devices (they typically require more bandwidth).

One of the known users was the Argentine Navy, who used it on their secure telephone network — SISTEMA XV-1 SUNCHO. The image on the right shows one of the original (modified) telephone sets that were used as the desktop terminal of the HC-235 scrambler. Apart from the HC-235, the Argentine Navy also used the (incompatible) DV-505 of the American manufacturer Datotek.
  
Note indicating use by the Argentine Navy

Apart from voice scramblers, the Argentine Navy also used a large quantity of Crypto AG (Hagelin) text encryptors of the HC-500 series. But as Crypto AG was owned by BND and CIA, these ciphers were also readable. During the Falklands War 1 of 1982, the messages of the Argentine Navy were read at large scale by GCHQ (UK). Not with help from NSA – they had refused to help the British – but from the Dutch Navy, who were already able to read Argentine's diplomatic ciphers. Although they did not share any decrypts with the British, they learned GCHQ how to break it themselves.

The Argentines were furious when they found out that there messages had been broken, and summoned Crypto AG's chief crypto­grapher to Buenos Aires for an explanation. This was not without risk, as the Argentine junta had a history of throwing peope to death from airplanes. 2

Crypto AG's chief cryptographer — codenamed ATHENA — decided to bluff his way out, by arguing that NSA and GCHQ had been able to break the voice scramblers and not the HC-500 text encryptors. After all, voice scramblers were notoriously insecure, everybody knew that. The HC-500 machines on the other hand, were absolutely secure and were definitely not read by NSA and GCHQ. The Argentines accepted the explanation and kept buying Crypto AG gear [3].
  
UK soldiers during the Falklands War. Photograph via History Collection on Pinterest[4].

Crypto Museum has several CRM-008 (HC-235) devices is its collection that are known to have been used by the Argentine Navy. Despite the fact that the exterior of these devices are partially corroded (from the influence of seawater), their internals are well-preserved and still fully intact.

  1. The Falklands War was an undeclared ten-week war between Argentina and the UK, over two British-controlled territories in the South Atlantic, known as the Falkland Islands.  Wikipedia
  2. This refers to the so-called death flights during the Argentine Dirty War (1974-1983), in which dissidents and enemies were dropped to their death from aircraft above the ocean.  Wikipedia

Parts
Voice encryptor Handset with PTT switch Desktop telephone set Radio adapter with speaker Radio interface Telephone adapter ATF-109 Power supply unit PSM-106
PSU
Encryptor   CRM-008, HC-230, HC-235
The military version of the scrambler is housed in a ruggedised green die-cast aluminium case, as shown in the image on the right. This is the CRM-008-001 or HC-235. All controls are at the front and the keypad at the right is protect by a hinged plastic cover.

The civil version was housed in a regular aluminium enclosure with wooden side panels, and was somewhat higher as it incorporated a mains power supply unit.
  
With open keypad

Handset   AHF-100
The default input/output device for the HC-235 scrambler is the Swiss military Microtel handset shown in the image on the right. It is similar to the ones that are used on other Swiss military equipment, such as field telephone sets.

The handset consists of a metal grip, with a mouthpiece (microphone) and a displaced earpiece (speaker). A push-to-talk (PTT) switch is mounted in the grip. The handset has a straight cable (as shown here) or a coiled one.
  
Handset with PTT switch for HC-235

Telephone set   ATF-114
When using the CRM-008 over an analogue (PSTN) telephone line, this special crypto phone had to be used instead of a standard one.

The special phone is in fact a standard telephone set that is modified for crypto use. It has extra switches and and an indicator to show that the connection is secure. The phone should be connected to the telephone line breakout box.
  
ATF-114 desktop telephone set

Radio adapter (1)   ARA-100-001
This junction box was used for connecting the CRM-008 to any type of (external) two-way radio set, such as military HF communications transceiver. It is fitted with an 10-pin LEMO plug that fits the data socket on the front panel.

The box has a built-in speaker with volume control – for monitoring – and has fixed wiring at the rear for connection of the input and output devices (transmitter and receiver).
  
ARA-100-001 External speaker unit with volume control

Radio adapter (2)   ARA-100-002
Instead of the speaker unit shown above, it was also possible to use the radio interface box shown in the image on the right. It connects to the same 10-pin LEMO socket on the front panel, marked 'DATA', but does not have an internal speaker.

The box shown in the image has fixed wiring from the transmitter and receiver, and a socket for connected of a pair of headphones. In practice, the headphones socket was sometimes replaced by a volume knob.

  
Radio connection box

Telephone adapter   ATF-109
When using the CRM-008 over a regular analogue PSTN telephone line, the breakout box on the right was generally used. It has banana socket for connection to a 2-wire line, plus two banana sockets for connection of the (regular) telephone set.

The breakout box has a fixed cable with a 10-pin LEMO plug at the end, that fits the DATA socket on the front panel.
  
Telephone breakout box

Power supply unit   PSM-106
The CRM-008 has a wide power input range from 10 to 30V
DC
. In a mobile environment, it was usually powered by the battery of a car (12V) or a truck (24V).

In a fixed setup, e.g. in an office, it could be powered from the mains, by using an external power supply unit (PSU), such as the one shown in the image on the right.
  
PMS-106 power supply unit for HC-235

With open keypad Handset with PTT switch for HC-235 Handset with PTT switch for HC-235, with coiled cable ATF-114 desktop telephone set With handset off-hook (note the PTT switch) Note indicating use by the Argentine Navy ARA-100-001 External speaker unit with volume control Connections at the rear
Radio connection box LEMO connector on the radio connection box Radio connectors (TX and RX) on the radio connection box Telephone breakout box PMS-106 power supply unit for HC-235 Wiring, mains voltage selector and fuses
C
×
C
1 / 14
With open keypad
C
2 / 14
Handset with PTT switch for HC-235
C
3 / 14
Handset with PTT switch for HC-235, with coiled cable
C
4 / 14
ATF-114 desktop telephone set
C
5 / 14
With handset off-hook (note the PTT switch)
C
6 / 14
Note indicating use by the Argentine Navy
C
7 / 14
ARA-100-001 External speaker unit with volume control
C
8 / 14
Connections at the rear
C
9 / 14
Radio connection box
C
10 / 14
LEMO connector on the radio connection box
C
11 / 14
Radio connectors (TX and RX) on the radio connection box
C
12 / 14
Telephone breakout box
C
13 / 14
PMS-106 power supply unit for HC-235
C
14 / 14
Wiring, mains voltage selector and fuses

Block diagram
Although the CRM-008 operates on analogue (speech) signals, the internal processing takes place in the digital domain. After the signal has been processed, it is converted back into an analogue signal, so that it can be transmitted over a standard narrow-band (radio) channnel.


The audio signal is first split into two frequency bands by means of filters A and B. These filters have a cut-off frequency of 1600 Hz with 5 selectable offsets (-300, -150, 0, 150 or 300 Hz). The two streams are then digitized and kept in separate buffers where they are processed further. In between the two frequency bands is a 1600 Hz pilot tone (P) that controls the synchronization between transmitter and receiver and also controls the built-in Automatic Gain Control (AGC).


In the buffers, each segment of 320 ms is divided into 8 individual sections of 40 ms each. The 8 sections of the A-channel are then mixed with the 8 sections of the B-channel in a pseudo-random order that changes every 320 ms, under control of the built-in digital key generator.


Finally, the scrambled data sections are converted back to analogue signals in two D-A converters and mixed together in filters C and D. As the output signal still contains the characteristics of regular speech, it can be transmitted over narrow-band channels without any problems. At the time (1970s), frequency/time domain scrambling (F/T) was considered safe against professional eavesdropping. Using modern correlation techniques however, it is easily defeated without the need to recover the actual key. F/T scrambling should now be regarded as extremely unsecure.



Interior
The interior of the CRM-008 (HC-235) can be accessed by releasing the eight large bolts (marked with a red circle) at the top of the device, and taking the top lid off. The device consists of three building blocks: (1) front panel, (2) processor assembly, and (3) a DC/DC power converter (
PSU
).

The front panel unit is a separate assembly that consists of four printed circuit boards (PCBs), that are mounted to the rear side of the front panel. The keypad, the LED display and the sockets are all integrated with this section.

The front panel is connected to the processor unit, via a blue 25-pin connector at the rear left. It can be removed by releasing the four red-marked bolts in the corners of the front panel, and pulling it out using the metal grips at the outer edges. The image on the right shows the front panel assembly, removed from the case.
  
Front panel PCBs

The internal power supply unit (PSU) is a DC/DC converter that is permanently mounted in the rear section of the enclosure. It is connected to the processor unit (at the centre) via a flatcable connector at the front right. After disconnecting the plug, the processor unit can be removed.

The processor unit consists of a slotted plastic frame, with a backplane
PCB
at the front. Three large
PCB
s are inserted into the frame from the rear and are connected to the backplane. A forth (smaller)
PCB
is fitted on top of the upper board.

At the top of the stack is the audio board. In holds the input and output amplifier and several pluggable high-quality audio filters. A digitiser (A/D converter) it mounted on top of the audio board as a plug-in unit. It is responsible for the conversion of speech into digital data, and forms a matched pair with the key generator board.
  
HC-235 interior

The key generator is at the centre of the
PCB
stack. It consists of a pseudo-random generator that is based on hard-wired discrete linear feedback shift registers (LFSRs), of which the initial state, or initialisation vector (IV), is determined by the cryptographic key entered by the user.

The key generator board also holds the volatile memory (
SRAM
) in which the user-entered key is stored. It is retained by means of a rechargeable NiCd battery that is also mounted on the board. It takes ~20 hours to fully charge this battery. 1 A fully charged NiCd battery should be able to preserve the key for more than one month [1].

At the bottom of the stack is the control board, that acts as a system-wide supervisor. It holds the memory in which the digitised audio from the two frequency domains (A and B) is stored, and swaps it under control of the key generator.
  
Two 4-bit bus-buffer-separators

The control board is also responsible for handling the user input and output from the front panel unit, and ensures that a new message key is generated each time a transmission is started — i.e. when the user presses the Push-To-Talk switch (PTT) that is located in the grip of the handset.

  1. Assuming that the NiCd battery is still healty.

HC-235 with top cover removed HC-235 without top cover Front panel electronics Front panel detached Front panel PCBs Plastic frame with PCBs removed from enclosure DC/DC power converter Plastic frame with PCBs
Power socket on the plastic frame Audio board with digitiser daughter card Digitiser board installed on the audio board AF filters Audio board detail Key generator board Two 4-bit bus-buffer-separators Control board at the bottom of the stack
D
×
D
1 / 16
HC-235 with top cover removed
D
2 / 16
HC-235 without top cover
D
3 / 16
Front panel electronics
D
4 / 16
Front panel detached
D
5 / 16
Front panel PCBs
D
6 / 16
Plastic frame with PCBs removed from enclosure
D
7 / 16
DC/DC power converter
D
8 / 16
Plastic frame with PCBs
D
9 / 16
Power socket on the plastic frame
D
10 / 16
Audio board with digitiser daughter card
D
11 / 16
Digitiser board installed on the audio board
D
12 / 16
AF filters
D
13 / 16
Audio board detail
D
14 / 16
Key generator board
D
15 / 16
Two 4-bit bus-buffer-separators
D
16 / 16
Control board at the bottom of the stack



Serial numbers
It appears that the first devices were sold in the late 1960s or the early 1970s, and that they were designated CRM-008-001 (002) and CRM-008-007. It is likely that the model number was later changed to HC-230 for the desktop version, and HC-235 for the ruggedised military version. So far, the following model numbers, part numbers and serial numbers have been observed:

Model P/N S/N Date 1 Remark
CRM-008-001 ST 528 879 5 535 375 ? Ebay
CRM-008-001 ST 529 537 5 535 387 1981 Argentine Navy 2
CRM-008-002 538 830A 5 535 594 ? Argentine Navy 2
HC-235 530 275A 5 535 479 1977 Argentine Navy 2
HC-235 530 275A 5 535 490 1977 Argentine Navy 2
HC-235 530 275A 5 535 496 1977 Argentine Navy 2
  1. Estimated manufacturing date, based on date codes on the components.
  2. Serial number recorded by Crypto Museum.

Connections
Power socket
At the rear of the device is a 4-pin LEMO socket for connection of a DC power source between 10 and 30V. The diagram below shows the layout of the socket when looking into the contacts. The upper two contacts go to the (-) terminal of the battery, whilst the lower two go to the (+).

  1. 0V
  2. 0V
  3. +10 to 30V
  4. +10 to 30V
Data socket
At the top left of the front panel is a 10-pin LEMO socket marked DATA. This socket is used for the connection to the outside world (telephone line, radio, etc.). The diagram below shows the layout of the socket when looking into the contacts.

  1. AFI
    AF input
  2. GND
    Ground (line)
  3. DXO
    Output to line
  4. AFO
    AF output
  5. SYNC
    Sync OK (open collector output)
  6. PTT
    Push-to-talk (input/output)
  7. /C
    Select Crypto mode (input)
  8. DXI
    Input from line
  9. -6V
    -6V power output
  10. +6V
    +6V power output
Handset socket
At the bottom left of the front panel is an 8-pin LEMO socket for connection of a handset, headset or a similar microphone/speaker arrangement. The diagram below shows the layout of this socket when looking into the contacts.

  1. SPK
    Speaker (1)
  2. GND
    Speaker (2)
  3. MIC1
    Microphone (1)
  4. -
    unused
  5. MIC2
    Microphone (2)
  6. PTT
    Push-to-talk (1)
  7. GND
    Push-to-talk (2) 1
  8. -
    unused
  1. In some handsets, the second contact of the push-to-talk switch (PTT) is wired to pin 2 rather than pin 7. These pins are functionally identical, as they are both wired to Ground (GND).

Specifications
Desktop model   HC-230
  • Local
    2-wire 600Ω
  • Line
    2-wire 600 Ω
  • Power
    110/220V AC 50/60 Hz, 9W (switch selectable)
  • Temperature
    -25°C to +55°C (storage: +40°C to +80°C)
  • Dimensions
    340 x 255 x 140 mm
  • Weight
    7.1 kg
Field model   HC-235
  • Local
    Mic: 2-wire ≥ 240Ω, Aux-in ≥ 10kΩ, Ear: 200Ω, Aux-out 600Ω
  • Line
    DX in: ≥ 12kΩ, DX out: 600Ω
  • Synchr.
    Continuously, pilot tone 1600 Hz ± 33 Hz
  • Temperature
    -25°C to +55°C (storage: +40°C to +80°C)
  • Dimensions
    375 x 240 x 80 mm
  • Weight
    5.7 kg
Common
  • Synchr.
    Continuously, pilot tone 1600 Hz ± 33 Hz
  • Sync delay
    Typically 2 sec (max: 5.5 sec)
  • Delay
    0.8 sec (after change-over)
  • AFC
    ± 100 Hz
  • Adj. ref.
    ±75 Hz, ±150 Hz
  • Key space
    1032
  • SRAM
    With iternal NiCd battery to retain key
Options
Help required
Please help us to expand this page, by proving additional information. We are still looking for the full (extended) operating instructions and for technical documentation of the CRM-008, HC-230 and/or HC-235, such as circuit diagrams etc. We are also looking forward to hearing from people who have worked with these devices in the field.

 Contact Crypto Museum


Documentation
  1. CRM-008 Short Form Description (English)
    3542B. Crypto AG, Date unknown. 1

  2. CRM-008 Short Form Instructions
    3456. Crypto AG, Date unknown. 1

  3. ARA-100-102 Radio Interface Adapter, operating instructions (English)
    3B841. Crypto AG, Date unknown. 1
  1. Document kindly provided by collector Immo Hahn [2].

References
  1. Crypto AG, Crypto Magazine 2009, number 1.
    Retrieved August 2009. p. 12: Crypto AG's family tree.

  2. Wikipedia, Falklands War
    Retrieved January 2020.

  3. Crypto Museum, Operation RUBICON
    February 2020.

  4. History Collection, 22 Photogrpahs of the Falklands War
    Pinterest, retrieved January 2020.
Further information
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Crypto Museum. Created: Monday 24 August 2009. Last changed: Monday, 10 February 2020 - 15:48 CET.
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