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Crypto AG
Online teleprinter encryptor · CRYPTROL - this page is a stub

T-450 was an electronic online encryptor for teleprinter signals (telex), introduced in 1969 by Crypto AG in Zug (Switzerland). The shift-register-based cryptologic of the device was developed by the US National Security Agency (NSA), and contained an exploitable weakness (backdoor) [3].

The device is house in a 4U 19" rackmount enclosure, and was usually mounted inside a ruggedised transit case, as shown in the image on the right. The civil variant had a bright front panel, but was otherwise functionally identical.   

The T-450 was developed in the mid-1960s, and was released in 1969, as a competitor to the Gretacoder 812, which was made by Crypto AG's main competitor Gretag. The device was in production until 1988, and was used in some countries well into the 1990s. In Iran it was even used until (at least) 2003, when the Americans invaded Iraq. It was succeeded by the CRT-320.

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Development of the machine was started in the mid-1960s, at the time when the company was still owned by its founder, Boris Hagelin. It was developed in parallel with the H-460Crypto AG's first fully electronic cipher machine – and uses a similar cryptologic that is based on shift-registers. As Crypto AG had strong ties with the American and German intelligence services, it was decided that the US National Security Agency (NSA) would develop the cryptologic.

Both the H-460 and T-450 have a built-in weakness, that makes it exploitable by the NSA. Such a weakness is commonly known as a backdoor. It allowed NSA, with appropriate computing power, to break its messages. But as it wasn't hidden too well, and in 1978 it was discovered by some of the customers. With a drop-in fix – provided by the NSA – the problems were solved, whilst the machine remained readable (exploitable) to them, albeit with increased computing power.

Over the years, Egypt was one of Crypto AG's best customers. And for the Americans, it was one of their top intelligence targets. 1 And because they were using the exploitable T-450, they were (unwittingly) also one of the best intelligence suppliers to them. But that changed in the autumn of 1978, when suddenly they began questioning Crypto AG's R&D chief when he was on a routine visit to Cairo. According to the Egyptians, all shift-registers were bad, and so was the T-450 [3].

In panic to save the day, the R&D chief offered the CRT-320 as a replacement. But as that was a secure (unbreakable) device, NSA demanded that the offer was retracted. In fact, he should never have offered in the first place. At NSA, cryptologist Dave Frasier quickly created a drop-in fix for the existing T-450 machines — an exploitable one, of course — that should be offered instead.

But at Crypto AG, one of the engineers had meanwhile fixed the cryptologic of the T-450 himself and that fix was not exploitable by NSA. The engineer didn't know that the Americans controlled the show, and was simply trying to serve the customer as best he could. With the best intentions. But this was not what NSA wanted. In the end, the R&D chief went to Cairo with the NSA-designed fix, and pretended it was his own invention. And the Egyptians accepted it [3].

  1. The Egyptians had been using their T-450 on high-level links during the Middle-East negotiations at Camp David in 1978, shortly before they began questioning its security.

Iran was another customer that used the T-450, and it was also an American intelligence target. They had bought the T-450 in 1983, but almost immediately after the introduction, the Iraqis broke it with help from the Russian KGB [1]. The break was possible, because of grave security mistakes on the side of the Iranians: they were sending multiple messages on the same key, allowing them to be broken in depth [2]. They even bought a Japanese computer – with suitable software and training for approx. 1000 personnel – to speed up the process.

Iran kept using the T-450 until at least 2003, when the Americans invaded Iraq. This was way past the economic life of the machine, and way past its 'expiration date'. By 2003 everyone should have known that the old shift-register-based machines were unsafe.

Help required
At present, no further information about the T-450 is available to us. We are currently looking for manuals, technical descriptions, circuit diagrams and in particular a detailed description of the cryptologic. If you can help any way, please contact us.

  1. T-450 Operating Instructions
    Crypto AG, Oskar Stürzinger. 3-K-629. Date unknown.
  1. Kevin Woods, et al., Saddam's Generals
    Perspectives if the Iran-Iraqu War. July 2010. p.21.

  2. Wikipedia, Cryptanalysis
    Retrieved january 2020.

  3. Crypto Museum, Operation RUBICON
    February 2020.

  4. Oskar Stürzinger, Chiffriertechnik Heute
    Vorlesung Krieg im Aether 1976/1977, ETH Zürich (German). p.26. 1

  5. Crypto AG, Company brochure
    Date unknown, but probably 1976. 24 pages. p.8.
  1. Retrieved from HAMFU History, December 2018.

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Crypto Museum. Created: Thursday 02 January 2020. Last changed: Friday, 12 January 2024 - 11:29 CET.
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