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Enigma Z
Numbers-only Enigma Z30 - wanted item

Enigma Z is an electromechanical rotor-based numeric cipher machine, developed around 1930 by Chiffriermaschinen AG in Berlin (Germany). It is the short-lived numbers-only branch of the Enigma cipher machine, and was intended for the encryption of numerical messages, such as (pre-coded) weather report. The letter Z probably stands for Ziffern or Zahlen (numbers). The machine is officially known as model Z30 and by its internal manufacturing designator Ch.16.

The existence of the Z30 was first disclosed by Arthuro Quirantes in April 2004 in an article in Cryptologia [1]. From documents that he had discovered in the Spanish archives, the machine had apparently been offered to the goverment in November 1931, along with other models [1].

In 2015, an actual Enigma Z30 was rediscovered in Sweden, and has since been described by Anders Wik in an article in Cryptologia in August 2016 [3]. The image on the right shows that particular version, taken from its wooden case. It is believed that this version is different from the one that was offered to the Spanish. It is likely to be older, as it features a simpler rotor stepping mechanism and its serial number (Z103) is lower.
  

The machine has a single-row keyboard with just 10 keys, marked 0 to 9. Likewise, the lamp panel has 10 lamps in a similar arrangement, and the cipher rotors each have 10 contact points at either side. The machine was intended for sending coded numerical messages, such as weather reports and text-based messages that were pre-coded by means of some conversion scheme. We would like to thank Anders Wik for allowing us to reproduce his Enigma Z photographs here [3].

Z30 inside its wooden case [3]
Z30 outside the wooden case [3]
Z30 seen from the front [3]
Perspective view of the Z30 [3]
Z30 interior [3]
Z30 interior seen from the top [3]
Z30 rotors [3]
Z30 rotors seen from the side [3]
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Z30 inside its wooden case [3]
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Z30 outside the wooden case [3]
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Z30 seen from the front [3]
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Perspective view of the Z30 [3]
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Z30 interior [3]
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Z30 interior seen from the top [3]
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Z30 rotors [3]
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Z30 rotors seen from the side [3]

Features
The image below shows the features of the Enigma Z30. The machine greatly resembles a regular Enigma machine, but is much smaller. Rather than the usual 26 keys and lamps (covering the letters A-Z of the Latin alphabet), it has just 10 in a single row, marked with the numbers 0 to 9.


At the top right is the power selector, which allows the user to choose between HELL (bright) DUNKEL (dark) and AUS (off). The device is powered by two 4.5V batteries connected in parallel, installed in the battery compartment that is located just below the power selector, under the hinged top cover. The lamp panel offers a clear view as it is sloped, just like on the Enigma G.


Versions
From surviving documents, it seems clear that two versions 1 of the machine were developed:

  • Z30 mark I · Standard version
    This version has three cipher rotors with 10 contacts at either side and a single turnover notch each. It has a simple (regular) stepping mechanism, and a movable 2 reflector (UKW). This versions features the same double stepping anomaly as the Enigma I [4]. Serial numbers are in the range Z-101 to Z-150. From surviving samples it is known that this model was built and sold to Sweden [2]. The machine featured here, is of this type.

  • Z30 mark II · Improved version
    This version features a cog-wheel driven turnover mechanism, similar to that of the Zählwerk Enigma and Enigma G. It has multiple turnover notches on each rotor and features irregular stepping. Like with the standard version, the reflector (UKW) moves during the encipherment. Serial numbers are in the range Z-151 to Z-200. As far as we know, there are no surviving examples of this version.
  1. To discriminate the two models, we will refer to them as Z30/I and Z30/II. This is not an official designator.
  2. Although this version features the simple stepping mechanism of the Enigma D (which has a settable but not movable UKW), the UKW of the Enigma Z can be moved by the leftmost cipher whel.

Standard version
It is known that the standard version has actually been manufactured and that it was supplied to Sweden an Chile [3]. In Sweden, three units were bought by the Svenska Tändsticks AktieBolaget (STAB), a company of the Swedish entrepreneur Ivar Kreuger, who was known as the Match King. 1 These machines have serial numbers Z101, Z102 and Z103, and are from the first production run.


It has also become known that during WWII, the German SIGINT and COMSEC agency – OKW/Chi – was interested in the Z30. Norwegian crypto historian Frode Weierud has found a document which shows that an Enigma Z30 with serial number Z106 was given on loan to OKW/Chi in September 1943 [5]. Interestingly, this document is signed by senior cryptologist — Dr. Erich Hüttenhein 2 — which might indicate that the Germans were investiging (or trying to break) a numerical cipher that was used by another country, or that they wanted to use the machine for their own purposes.

  1. Kreuger had control over approx. 70% of the worldwide production of matches at the time. His companies Kreuger & Toll and STAB, were in possession of banks, mines, real estate and other companies [3].
  2. During WWII, Erich Hüttenhain was the chief cryptologist of the Third Reich. After the war, he worked for the new German intelligence agency Organsation Gehlen (OG), which eventually became the BND.

Rotors   standard version
The machine has three cipher rotors (I, II and III) that are installed onto a spindle. The spindle can be removed from the machine after unlocking the reflector (UKW) and shifting it aside. The cipher rotors can be placed on the spindle in six possible orders. The UKW can not be removed but can manually be set to any of the 10 possible positions at the start of the procedure.

Rotors of the standard Enigma Z30 [3]

Each rotor has a single turnover notch that is located next to the number 2. It causes a turnover of the adjacent rotor (i.e. the rotor to its left) after the number 9 has been visible in the window on top of the machine. The position of the ring can be altered (Ringstellung), but does not alter the position of the turnover notch with respect to the wiring. This is different from regular Enigma rotors. As a result, the ring setting does not have any effect on the strength of the cipher [3].

Wiring   standard version
Below is the wiring of the cipher rotors, as it was recovered from the machine with serial number Z-103 by Anders Wik in Sweden. His findings were published in Cryptologia in 2016 [3].

Rotor 1234567890 Notch Turnover #
ETW 1234567890      
I 6418270359 2 9 1
II 5841097632 2 9 1
III 3581620794 2 9 1
UKW 5079183642 2 9 1
Stepping   standard version
The standard version of the Z30 has the same stepping mechanism as the Enigma D and the later Enigma I. This means that it features simple stepping – similar to the odometer of a car – and that it exhibits the same double stepping anomaly that was described by David Hamer in 1997 [4].

In the Z30 however, the third cipher rotor from the right (i.e. the one closest to the reflector) can cause the reflector to make a step when its notch is engaged from the rear by the corresponding pawl. This is different from other Enigma machines with simple stepping, such as Enigma D and Enigma K, in which the UKW is settable but not movable.

Power selector
Note that this version has a rather strange type of power selector, which (compared to other Enigma models) is mounted upside down and has three rather than four positions, marked hell (bright), dunkel (dark) and aus (off) respectively. It is shown here in the hell position:




Improved version
In November 1931, the Enigma manufacturer — Chiffriermaschinen AG — offered a number of different Enigma machines for sale to the Spanish Embassy in Berlin. This included an offer for the Enigma Z [1]. The photographs on the hastily translated brochure, however, show a machine with an improved cog-wheel driven turnover mechanism, similar to that of the Zählwerk Enigma. It has a cog-wheel release lever in the top left, which is not present on the standard version.

This version also has screw terminals for the connection of an external power source, just like the standard Enigma, and the power selector at the top right has an extra position for this.

It is uncertain whether this machine was actually built, but the image in the brochure (shown on the right) shows a machine with serial number Z-155 or Z-165, and the wooden lid of that machine is modified to accomodate the release lever at the top left. It seems therefore likely that this was actually a production machine and that the serial numbers ranged from Z-151 to Z-200.

As the serial numbers on the improved version are higher than the ones found on the standard version, we assume that it was developed later, but that the model number (Z30) was the same.

As far as we know, the Spanish Goverment did not buy the Enigma Z30 machines, but it is known that they were sold to other countries, in particular to Sweden and Chile, although this was probably the earlier standard version [2].
  

Also note that the improved version came with a green contrast filter that is stowed inside the lid of the wooden transit case. It has notches at the short sides by which it can be fitted to the two screws at either side of the lamp panel. These screws are not present on the earlier version.

Improved Z30 with the lid closed
Improved Z30 with the lid open
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Improved Z30 with the lid closed
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Improved Z30 with the lid open

Interior
Standard version
The diagram below shows the interior of the Z30 with serial number Z103, after the hinged top cover has been raised. At the center are the cipher rotors, which show great resemblance to those of the regular Enigma machines, albeit with just 10 steps rather than the usual 26. There are three cipher rotors, plus a movable (driven) reflector (UKW) at the left. The ETW is at the right.


At the bottom is the keyboard, which has 10 buttons, numbered from 0 to 9. Above the keyboard is the lamp panel, which consists of a single row with 10 flat-faced light bulbs. In between the keyboard and the lamp panel is a metal frame that can hold up to eight spare light bulbs.


Documentation
  1. La maquina de cifrar números a lámperas incandescentes Enigma Z30
    Operating instructions for Enigma Z30, Mark II (Spanish).
    Chiffriermaschinen AG, Berlin. Undated (probably 1930).
References
  1. Arthuro Quirantes, Model Z: A numbers-only Enigma version
    Cryptologia, April 2004.

  2. Frode Weierud, Enigma History
    Forthcoming publication, expected in 2010.

  3. Anders Wik, Enigma Z30 retrieved
    Cryptologia Volume 40, Issue 3, 2016.

  4. David Hamer: Actions involved in the 'double stepping' of the middle rotor
    Cryptologia, January 1997, Volume XX, Number 1.

  5. ChiMaAG, Empfangsschein Enigma Z-106 1
    Receipt, signed by Willi Korn (ChiMaAG) and Erich Hüttenhain (OKW/Chi).
    30 September 1943. TICOM PAAA, T1717.
  1. Document kindly provided by Frode Weierud [2].

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© Crypto Museum. Created: Monday 14 September 2009. Last changed: Sunday, 09 July 2023 - 09:31 CET.
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