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Enigma Z
Numbers-only Enigma Z30 - wanted item

The Enigma Z is a rather strange leaf on the Enigma Family Tree. Although it is clearly based on the design of Enigma D, it has only 10 keys and 10 lamps, each marked with the numbers 0 thru 9. It was used for the encryption of numerical messages (i.e. messages that were pre-coded), such as weather reports. 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 published 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, outside 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 wheel stepping mechanism and its serial numbers are lower.
Enigma Z30 (standard version). Photograph kindly supplied by Anders Wik [3].

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 wheels 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 should 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 wheels [3] Z30 wheel 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 wheels [3]
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Z30 wheel seen from the side [3]

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.

Z30 inside its wooden case [3]

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.

The machine has three cipher wheels that are mounted onto a spindle. The spindle can be removed from the machine after unlocking the reflector (UKW) and shifting it aside. The cipher wheels can be placed on the spindle in any possible order. The UKW can not be removed but can be placed manually into any of 10 possible positions at the start of the procedure. Each wheel has a single turnover notch. Apparently there is no ring setting (Ringstellung) as on a regular Enigma.

Wheels of the standard Enigma Z30 [3]

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

  • Standard version
    This version has three cipher wheels with 10 contacts at either side and a single turnover notch on its circumference. It has a simple (regular) stepping mechanism and a settable reflector (UKW) that does not moving during the enciphering. Serial numbers are in the range Z-101 to Z-150. It is certain that this model was built and sold to Sweden [2].

  • Improved version
    This version features a cogwheel-driven turnover mechanism, similar to that of the Zählwerk Enigma. It has multiple turnover notches on each wheel and features irregular stepping, just like the Enigma G. Furthermore, the reflector (UKW) moves during the encipherment. Serial numbers are in the range Z-151 to Z-200.
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].
Image of the improved version of the Enigma Z30, taken from the brochure [1]

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

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 wheels, 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 wheels, plus a settable reflector (UKW) at the left. The ETW is at the right.

Interior of the standard Enigma Z30 [3]

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.

  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.
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© Crypto Museum. Created: Monday 14 September 2009. Last changed: Friday, 23 February 2018 - 22:31 CET.
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