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EMU Alpha
Electronic Message Unit - wanted item - this page is a stub

EMU Alpha, also known as EMU-A, was an electronic messaging device, developed in the late 1980s by Philips subsidary MEL in Crawley (UK), for use with the British special forces radio UK/PRC-319. It is the alphanumeric successor to the BA-1304 (EMU), and features built-in data encryption. The algorithm however, was developed by the NSA, and contains a backdoor [1].

The device has a 35 button keypad and a liquid crystal display (LCD) at the top. It has the same form factor as its predecessor and can be fitted in the same bay on the body of the PRC-319.

Messages can be up to 2000 characters long, and are transmitted at high speed (burst) to reduce the chance of interception and discovery.

Forward Error Detection and Correction (EDC) is used to reduce transmission errors, according to the military STANAG 4202 standard. In addition, the messages are interleaved and encrypted.

The encryption algorithm was developed by the US National Security Agency (NSA) and was implanted by Philips Usfa in The Netherlands. At the time, manufacturer MEL was a subsidary of the Philips conglomerate and Philips Usfa was its military division, which had a department that specialised in cryptography. By letting Philips supply the algorithm, no suspicion was raised.
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It is known that the encryption algorithm is flawed – it contains a backdoor – but its details are still unknown. For this reason we have made the contents of the EPROMs available below. This page currently acts as a placeholder for information about the EMU Alpha and the NSA-supplied encryption algorithm, and will be updated as and when new information becomes available.

WANTED ITEM — Crypto Museum is still looking for an EMU Alpha for its collection. In addition, we are looking for any documentation, such as brochures, operating instructions and service manual(s).  Contact us
  1. Cees Jansen, former cryptographer at Philips Usfa
    Personal correspondence, January 2022.
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Crypto Museum. Created: Monday 14 February 2022. Last changed: Saturday, 19 February 2022 - 09:58 CET.
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