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Tarolex 19"
Online key generator - Wanted item

Tarolex was a key stream generator for a modified Ecolex-IV cipher machine, developed by Philips Usfa in 1966 at the request of the Dutch Army. It was introduced in 1967, and allowed an Ecolex-IV machine to be used with a pseudo-random key stream, rather than with an OTT. The machine is also known as UA 8084 (Philips) and KL/TGA-3128 (Royal Dutch Army).

The image on the right shows a complete Tarolex setup [1]. The Tarolex itself is at the bottom right. On top of the Tarolex is a standard Siemens T-100 teletype machine.

The modified Ecolex-IV is at the left. The rear tape reader (that was used for the key tape) is replaced by an interface with a connector. A cable runs from the connector on the Ecolex-IV to the front of the Tarolex. This way, the key stream, generated by Tarolex, is fed to the Ecolex-IV instead of the usual key-tape.

Tarolex is housed in a heavy TEMPEST proof case as is clearly visible in the photographs below. The actual key settings are behind a door on the right half of the unit (see below).
  

Tarolex was developed at the request of the Royal Dutch Army, who wanted a solution for the key-tape distribution problem of the existing mixer machines, such as the Ecolex-IV and, to a lesser extent, the Ecolex-II. In order to be able to connect Tarolex in place of the existing key-tape reader, a suitable interface was developed as well [2].

Tarolex was based on the design of TROL, that was developed between 1962 and 1965 for a NATO evaluation. TROL was never built however, as Philips lost the evaluation to ALVIS (BID 610) [2]. Tarolex is in fact a combination of the separate items that TROL consisted of. The name TAROLEX was also derived from TROL and stands for Tapeless Rotorless Online Encryption. The suffix 19" to the name was used to distinguise the machine from the earlier TROL development. In total, 151 Tarolex 19" units were built.

Although development of the Ecolex-X had already started in 1965, it would not be ready before 1972. Tarolex was therefore used as a gap-fill solution until Ecolex-X was ready. Nevertheless, many Tarolex units remained in service after the Ecolex-X was rolled out in 1972.

Possible setup with Tarolex Possible setup with Tarolex Close-up of the controls and the tape reader Close-up of the tape reader Unknown rack with serveral units, including a Tarolex. Prabably a test setup. Early prototype of Tarolex 19 Early prototype of Tarolex 19 Testing an early prototype of Tarolex 19 Rear view of an early prototype of the Tarolex 19

Daily key settings
The principle behind the Tarolex is that a short key is used to generate a longer key. Inside the machine is a complex Pseudo-Random Number Generator (PRNG) that generates an evenly spread, difficult to predict, stream of characters with a very long period. The latter means that it does not repeat itself for quite a long time. The key tape is used as the so-called seed.

Behind the door on the right half of the front panel are the controls and, more importantly, the key tape reader. Although the unit was fed with a standard 5-level piece of punched tape, it is not a tape reader in the usual sense. Rather than running through the reader and reading the characters one-by-one, Tarolex reads all characters from the key tape at once.

The tape reader itself, consists of yet another 'door' behind which 110 pins are located. These pins are used to read the key tape that is 22 characters long (22 x 5 bits = 110 bits). As a result, there are 2110 possible combinations, which is approx. 1033.

The image on the right shows the opened tape reader of the Tarolex. The 110 pins of the reader are clearly visible in the bottom half of the image. The pins are arranged in the same pattern as on a standard punched paper tape. Once the tape was in place and all doors were closed again, Tarolex was ready for use.
  
The opened tape reader of the Tarolex

The advantage of the combination Ecolex-IV and Tarolex was that, in synchronous mode, the system kept sending a cipher stream, even when no new information was typed on the teletype unit. This way, it was impossible for an interceptor to determine the start or end (and hence the length) of a message. Furthermore, it was impossible to recognize the operator from his or her typing speed.

Public display
The image on the right was taken at the Royal Dutch Signals Museum (Museum Verbindings-Dienst) in 2009. They used to have a Tarolex machine on public display.

Unfortunately, the door of the machine was closed and no further information was available at that time.

 More about the Signals Museum
  
Tarolex

Tarolex Modified Ecolex-IV Close-up of the removed tape reader

References
  1. Photographs from Philips Usfa
    Crypto Museum Archive.

  2. Philips Usfa, Internal Memo L/5636/AvdP/JG
    23 August 1982, page 3.

  3. Koninklijke Landmacht, Sleutelgenerator KL-TGA-3128, Bediening
    Tarolex User Manual and Technical Description (Dutch).
    Royal Dutch Army. 11 July 1968. Updated 24 January 1980.
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