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Hans Bühler
Former sales representative of Crypto AG

Hans Bühler was a sales representative of Crypto AG (Hagelin) in Zug (Switzerland). As such, he frequently travelled the Middle East, selling cipher machines to countries like Saudi Arabia and Iran. In 1992, The Iranians suspected the Hagelin equipment to have a backdoor that gave the Americans access to their traffic. Bühler was arrested and spent the next nine months in prison.

Bühler – completely unaware of any manipulation with the machines – was interrogated three times a day for nine months and was finally released in 1993, after the bail of US$ 1,000,000 was payed by Crypto AG. This incident certainly doesn't mark the finest period in Crypto AG's history.

Immediately after his release from prison and his subsequent return to Switzerland, Bühler was dismissed. In addition, the company also wanted him to reimburse the US$ 1,000,000 bail. Bühler then went public and confined the entire story to a revealing book that was published in 1994 [1].
  
Cover of the book 'Verschlüsselt, Der Fall Hans Bühler'

The Swiss Federal Police – the Bundesanwaltschaft – has investigated the matter and questioned several people, and it is said that no irrefutable evidence against Crypto AG was ever found. The outcome of the investigation however, remains classified to this day and repeated requests from journalists for public disclosure of the results of the investigation have so far been denied.

Since Hans Bühler went public, some of his former colleagues have decided to come out as well. Former software engineer Jürg Spörndli confirmed that the company was visited frequently by NSA specialists and that on several occasions he was instructed by his manager to swap a crypto­graphic algorithm that he had developed, for an alternative one – supplied by the NSA – that was clearly weaker [2]. This case shows great similarity to the weakening of the Philips PX-1000 [3].

The story of the deliberate weakening of the algorithms at the request of the NSA, is corroborated by former Crypto AG director Oskar Sturzinger, in an interview with Crypto Museum in November 2008 [4]. Previously classified documents — that were partly released by the NSA in 2014 — have meanwhile produced convincing evidence of a secret deal between Crypto AG and the NSA from 1951 onwards [5]. In January 2018, it was announced that Crypto AG would be split, and that the international part would be taken over by a Swedish company. Hans Bühler died in August 2018.


Publications
  1. Verschlüsselt, Der Fall Hans Bühler
    ISBN 3-85932-141-2. 1994.
References
  1. Verschlüsselt, Der Fall Hans Bühler
    ISBN 3-85932-141-2. 1994.

  2. Line Dugstad & Osman Kibar, Den skjulte partneren
    Dagens Næringsliv. Website. 2 january 2015 (updated 13 February 2015).

  3. Crypto Museum, Deliberate weakening of the PX-1000 by the NSA
    14 January 2016.

  4. Oskar Stürzinger, Interview with Crypto Museum
    Basel, 7 November 2008.

  5. Crypto Museum, Secret NSA/Hagelin deal
    30 July 2015.
Further information
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