30-character version of CX-52
- under construction
CX-52/30 1 was a mechanical pin-and-lug cipher machine,
developed around 1952 by the Swede
Boris Hagelin, manufactured by
AB Cryptoteknik in Stockholm (Sweden)
and sold by Crypto AG in Zug (Switzerland).
It is the 30-character variant of the standard
26-character CX-52, and was intended for alternative languages.
It should be considered the secure version of the
Like the standard CX-52,
this machine has
six removable and pin-configurable cipher wheels,
each with a different coprime number of steps, plus a
or drum, with sideways movable bars with configurable tabs, or
The main difference with the regular CX-52, is that it is made for a
30-character alphabet, such as Russian 2 or Arabic. This affects the
letter selector disc
at the front left, but also the
double print head inside.
The machine shown here, is a Latin variant. In addition to the letters A-Z,
it has four additional markup symbols:
∧, ∨, ≡ and |||.
The extra symbols could be used for a variety of (user-defined) purposes,
such as spaces, line-breaks, shift-up, shift-down, etc. Converting the machine
for, say, Cyrillic or Arabic alphabets, only requires swapping of the letter
disc and the two print heads, and can be done in minutes.
The suffix '/30' was a secret identifier, used internally at
It is not displayed on the
serial number tag, where it is simply
designated CX-52. The secret suffixes are listed in the
Gentleman's Agreement .
The Russian (Cyrillic) alphabet has more than 30 characters, but 30
are generally enough to write comprehensible text. For example:
the Russian M-125 Fialka cipher machine
also uses 30 letters.
The diagram below gives a quick overview of the features of the CX-52/30.
The machine is nearly identical to the standard CX-52, but supports
30 different characters, rather than just 26. For this reason, the
letter selection disc
at the front left, has 30 positions. Although this machine was
initially intended for alternative languages, such as Arabic and Russian,
the machine shown here demonstrates that there were also machines
with 30 character positions
for the Latin alphabet.
The print heads
– hidden under the letter selection disc
at the front left – have the same 30 symbols around their circumference.
At the right are the six removable – and interchangeable –
each of which has a different number of steps. The number of steps on the
wheels are relative primes, or coprimes, 1 in order to ensure a maximum
length cipher period. 2
The wheels are identical to those of a regular CX-52.
Some machines came with a total of 12 wheels, 6 of which were installed
in the machine at any given time, subject to the current KEY instructions.
Behind the cipher wheels
is a cage that rotates
when the advance lever at the right side is operated.
The cage has 32 sideways movable bars, each of which can be configured with
removable lugs (tabs). Some of these bars are responsible for the number of
steps the printer, and hence the letter selection disc, makes when operating
the advance lever.
Each machine came with a set of tools and supplies, that were stowed inside
the cover, each held in place by one or more metal clips. The image above shows
the items that were found inside the cover of the machine featured here.
Note that the screwdriver has become brittle over the years.
The machine shown here, has the following features:
- No F/V selector
- Removable letter ring with fixed symbols (symbols can not be swapped)
- 30 characters, rather than 26
- Latin alphabet with 4 additional symbols
The number of steps of a particular wheel does not share
a common factor with any of the other wheels .
The number of characters (steps) before the key stream repeats itself.
The CX-52 was considered a more secure version of the
C-52. It features irregular stepping of the cipher wheels,
and was internally known at Crypto AG as a
Class 2 machine, 3 whereas the C-52 was a Class 1 machine
and featured regular stepping. It was generally assumed that the latter
was easily breakable by the US
National Security Agency (NSA),
using automated solutions.
It is known from surviving documents – in particular the
and Operation RUBICON
– that, at the time of its introduction,
the CX-52 was virtually unbreakable for the
This is why NSA
(and later the CIA as well)
did everthing in their power
to ensure that the machines that were made for certain countries or customers,
were cryptographically weakened from 1955
Such deliberate weakening of a cipher system is also known as a
It is likely that the machine featured here, does not suffer from such a
backdoor, as it appears to come from a very early production run.
According to the serial number tag,
it was manfuctured in the old factory in Stockholm (Sweden),
before production of the CX-52 was moved entirely to Zug (Switserland), and
before the Gentleman's Agreement
of 1955 had come into effect.
When we received the CX-52/30 featured here, it was completely
blocked. The mechanism could not be moved and the letter selector was
binding. The previous owner had been unable to open the hinged lid over
the printing mechanism.
The machine showed minor traces of rust,
especially at the center of the letter dial, indicating that the cause of
te problems was below the hinged lid.
First, the cipher wheels were removed to ensure that they were not binding,
and to reduce the load on the drum mechanism. Next, with a lot of patience,
letter selection knob – at the left side of the machine – was gently moved
back and forth by just a few millimeters, until it was in the right
position to allow the hinged lid over the printing mechanism to be opened.
With the lid open, it was possible to remove the axle with the print heads,
and to find out why the mechanism was blocked. In turned out that the
root cause was the letter selection disc.
After many years of storage, possibly in a humid environment, a thin layer
of rust had built-up between the letter selection disc and the lid,
effectively binding the disc to the lid.
The rust may also have been caused by gases
from the acid-containing ink. As a result, the letter
selection knob – which drives the letter selection disc via a 90° cogwheel –
could not be rotated either.
First the letter ring was removed from the lid, by
loosening a recessed screw
in the side of the lid, and pressing the push-pin on the inside of the lid
to tilt the ring, as shown in the image above.
The disc could now be removed by releasing the screw at the centre, but this
was slightly more difficult than anticipated, as it was rusted to the disc.
But finally, after a treatment with a bit of penetrating oil, it gave in and the
disc could be removed. The rear side of the disc appeared to have a thin layer
of rust, which had affected the green paint on the top surface of the metal lid.
The rust was gently removed from the rear of the disc, by means of a brass-brush,
which leaves virtually no traces. Next it was decided to remove the paint
residue from the top surface of the lid
— the part that is hidden under the
letter selection disc — in order to make it smooth again.
Next, the axle with the print head – shown in the image on the right –
was examined. Normally, the two heads can be separated by pulling-out the
knob at the left. In this case however, all parts were firmly binding
together, due to a combination of dust, dried oil (possibly WD-40) and ink,
that had accumulated over the years.
After removing the items from the axle – each held in place by a
bended steel spring – all items were carefully derusted
and cleaned, before they were reassembled, as shown in the image on the right.
The additional symbols are clearly visible.
- The Hagelin Cryptographer, Type CX-52
User Manual in English, French and German. 36 pages.
Crypto AG. 1 January 1962.
- The Hagelin Cryptographer, Type CX-52 (photographs)
Photographs belonging to the above manual [A]. 4 pages.
Crypto AG. 16 January 1951.
- Spare parts catalogue CX-52 (No 21101 etc)
Spare parts list with instructions in English, French and German. 35 pages.
Crypto AG. 1 January 1962.
- Appareillage pour Chiffrement à Bandes Perforées
Instructions for CX-52/RT (RT/CX), B-621 and PEB-61 (French).
Doc. 2268. Crypto AG, Oskar Sturzinger. February 1969. 5 pages.
- Die Klaviatur B-621 (B-62)
B-621 (B-62) keyboard attachment for CX-52 (German). 14 pages (with schematics).
Doc. 1188a. Crypto AG, Oskar Sturzinger. June 1968.
- CX-52 Condensed Instructions
Doc. 3035b. Crypto AG, BH. November 1957.
- CX-52 Description
Doc. 3027. Crypto AG, Oskar Stürzinger, August 1956.
- CX-52 Service Instructions and Maintenance
Doc. 3099. Crypto AG, BH, January 1959.
- CX-52 Spare parts catalogue
Doc. L-013. Crypto AG, May 1956.
- CX-52 Specification
Doc. I-3006c. Crypto AG, Oskar Stürzinger, November 1957.
- B-52 Service Instructions
Doc. E-3121a. Crypto AG, Oskar Stürzinger, 12 November 1956 — July 1961.
- B-52 Ersatzteilkatalog (spare parts catalogue)
Doc. L-027. Crypto AG, 10 October 1957.
- B-52 Keyboard attachment unit
Doc. 3052a. Crypto AG, Sn, January 1958.
- C-52 Trouble Shooting
Doc. 3225a. Crypto AG, date unknown.
- Usage of Hagelin cryptographer CX-52
Doc. <unknown>. 25 November 1964.
This story was later translated by Boris Hagelin into English. It can be downloaded here.
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© Crypto Museum. Created: Wednesday 15 July 2020. Last changed: Wednesday, 15 July 2020 - 08:11 CET.