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Hagelin HC-550   CRYPTOMATIC
Electronic desktop cipher machine

The HC-550 and HC-580 are desktop cipher machines developed by Crypto AG (Hagelin) in Zug (Switzerland) in the 1980s. It is part of the CRYPTOMATIC 500 family of devices and is compatible with the HC-520, HC-530 and HC-570. The machine consists of a modified Siemens T-1000/CA teleprinter with a large black tray containing the actual cipher machine mounted at the bottom.
 
The image on the right shows a typical HC-550, which is nearly identical to the Siemens T-1000 telex it is based on. In this case, the machine has a tape reader to the right of the keyboard and a tape puncher bolted on at the right. Suitable five-level paper tape should be fed in from the rear. The machine itself prints its output directly onto a paper roll that is also fed in from the rear.

A black slimline metal cabinet is mounted to the bottom of the T-1000. At the front are two physical keys, one for entering the cryptographic key and one for selecting the mode of operation.
  
Hagelin HC-550 cipher machine

The HC-550 is an off-line machine, whilst the HC-580 can also be used on-line. Both machines can also be used as an ordinary teleprinter when used in a line-connected mode. The teleprinter is only used as an input/output device, or terminal, whilst the cipher unit at the bottom bottom takes care of the actual encryption, similar to the Philips Aroflex and Timmann's TST-9669-11.

The use of a standard teleprinter greatly simplifies the design and allows different typefaces to be used, such as Latin, Arabic, Farsi, etc. Furthermore, this machine can print on ordinary paper, unlike the HC-570 which prints on thermal paper. The advantage of the HC-570 on the other hand, is the higher speed at which it can process and print its data. The machines are compatible.
 
Hagelin HC-550 cipher machine Front view Keyboard and control buttons Tape puncher Tape reader Master key Operator's key Rear side
Controls
The diagram below shows a typical Hagelin HC-550 in operation. The machine has all features of a standard Siemens T-1000 teletypewriter, including an external paper tape puncher mounted at the right. The actual cipher machine is mounted under the T-1000. It is operated through two physical keys and 6 push-buttons at its front panel. Additional features are available through the special function keys of the T-1000, some of which are not present on a regular T-1000 telex.


To operate the machine, the leftmost physical key is used to enter the Basic cryptographic Key (BK). The key is used to toggle between BK and operational mode. Turning the key in the opposite direction, allows the machine to be opened, much like the motor compartment of a car. The rightmost physical key is marked C/D and is used to toggle between ciphering and deciphering.

 
Compatible machines   Cryptomatic 500
Pocket version, resembling a calculator Suitcase version Desktop model, based on Siemens T-1000 Desktop model Desktop model, based on Siemens T-1000 Unknown model
HC-590
Interior
The Hagelin HC-550 cipher machine is mounted to the bottom of the Siemens T-1000 telex, with a hinge at the rear acting as a pivoting point. The interior can be accessed by turning the leftmost physical key at the black front panel counterclockwise. This unlocks a latch at the front centre.
 
Once the latch is unlocked, the teleprinter can be tilted backwards by lifting it at the front. After tilting the machine by approx. 45°, a metal stub at the right can be raised to prevent the machine from falling back, in a similar manner as the hood of the engine compartment of car.

Inside the device are two large printed circuit boards (PCBs), each of which takes up about half the available space. The PCB at the front holds the microprocessor, the I/O interface and some logic, whilst the board at the rear holds the RAM memory and the EEPROMs with the firmware.
  
Close-up of the contents of the black tray

The cable at the front right connects the crypto device to the front panel buttons. At the left side is a small PCB with a 15-pin sub-D test connector and the Zeroize button, which is marked EMCY (emergency). The button is covered by a protective black plastic cap. Pressing it, clears the RAM memory and purges the cryptographic keys.
 
HC-550 interior Close-up of the contents of the black tray Processor detail Firmware Connection to the Siemens T-1000 Leftmost physical key Switch behind physical key Test connector and zeroize button
Technical specifications
HC-550
  • Mode: off-line
  • Line input: Receipt of cryptograms via lines
  • Basic key: 7 keys can be stored, each with 1028 variations
  • Message key: 1.4 x 10 variations.
  • Period: 1054 steps
  • Memory: 8000 characters
  • Speed: 50, 75 or 100 baud
HC-580
  • Mode: off-line and on-line
  • Line input: 7 and 7½ unit start/stop (plain or cipher text)
  • Basic key: 21 keys can be stored, each with 1028 variations
  • Message key: 1.4 x 10 variations.
  • Period: 1054 steps
  • Memory: 8000 characters
  • Speed: 50, 75 or 100 baud
Documentation
  1. HC-550 ML, Short-Form Instructions
    3K639b. Crypto AG. Date unknown.

  2. Cryptomatic HC-550, Bedienungsanleitung
    Operating Manual (German). 1B641. Crypto AG. Date unknown.

References
  1. Jane's Military Communication 1986
    ISBN: 0-7106-0824-1

Further information

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Crypto Museum. Created: Friday 22 April 2016. Last changed: Saturday, 22 April 2017 - 19:26 CET.
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