A Secure Phone Fit For A Prime Minister

The curtain of state secrecy which surrounds the type of government agency known primarily by initialisms is all-encompassing and long-lived, meaning that tech that is otherwise in the public domain remains top secret for many decades. Thus it’s fascinating when from time to time the skirts are lifted to reveal a glimpse of ankle, as has evidently been the case for a BBC piece dealing with the encrypted phones produced by GCHQ and used by Margaret Thatcher in the early 1980s. Sadly, it’s long on human interest and short on in-depth technology, but nevertheless from it can be deduced enough to work out how it most likely worked.

We’re told that it worked over a standard phone line and transmitted at 2.4 kilobytes per second, a digital data stream encoded using a paper tape key that was changed daily. If we were presented with this design spec to implement in a briefcase using 1980s components, we’d probably make an ADPCM (Adaptive Differential Pulse Code Modulation) system with an XOR encryption against the key, something we think would be well within the capabilities of early 1980s digital logic and microprocessors. We’re wondering whether the BBC have made a typo and that¬† should be kilobits rather than kilobytes to work on a standard phone line.

No doubt there are people in the comments who could tell us if they were willing to break the Official Secrets Act, but we’d suggest they don’t risk their liberty by doing so. It’s worth noting though, that GCHQ have been known to show off some of their past glories, as in this 2019 exhibition at London’s Science Museum.

Pit Your Wits Against British Spooks

The festive season is upon us, and for Brits of a technical bent that means it’s time for the GCHQ Christmas Challenge. Sent out annually as part of the Christmas card from the UK’s intelligence centre, this is a chance for would-be spooks to pit their wits against some of the nation’s cleverest cryptologists whose work you’ll never have heard of.

This year the puzzle is aimed at those with a secondary school education, in the hope of fostering an interest in maths and science in younger people. It’s a series of puzzles of ascending difficulty, but don’t be lulled into a false sense of security by the earlier ones being easy, to complete the set will still require some brain power.

We’re guessing that as in previous years, this puzzle will garner a significant quantity of entries. It’s a successful public relations exercise from the agency which like all such organisations has felt its fair share of controversy in its time. There may thus be readers who regard it with some suspicion, but it’s fair to say it’s not the only such popular exercise from a govenment agency. If meanwhile you fancy a bit of GCHQ history, we caught their Science Museum exhibition back in 2019.

Inside The Top Secret Doughnut: A Visit To GCHQ

There’s an old joke that the world’s greatest secret agent was Beethoven. Didn’t know Beethoven was a secret agent? That’s why he was the greatest one! While most people have some idea about the CIA, MI6, and the GRU, agencies like the NRO and GCHQ keep a much lower profile. GCHQ (Government Communications Headquarters) is the United Kingdom’s electronic listening center housed in a 180 meter round doughnut. From there they listen to… well… everything. They are also responsible for codebreaking and can trace their origin back to Bletchley Park as well as back to the Great War. So what’s inside the Doughnut? National Geographic managed to get a tour of GCHQ and if you have any interest in spies, radios, cybersecurity, or codebreaking, it is worth having a look at it.

Of course, only about half of the GCHQ’s employees work in the Doughnut. Others are scattered about the UK and — probably — some in other parts of the world, too. According to the article, GCHQ had a hand in foiling 19 terrorist attacks, arresting at least two sex offenders, and prevented about ¬£1.5 billion of tax evasion.

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Espionage On Display As GCHQ Hosts A Temporary Exhibit

At the top of the British electronic intelligence agency is the Government Communications Headquarters (GCHQ), a very public entity whose circular building can easily be found by any inquisitive soul prepared to drive just off the A40 in Cheltenham which is about two hours west of London. But due to the nature of its work it is also one of the most secretive of UK agencies, from which very little public information is released. With over a century of history behind it and with some truly groundbreaking inventions under its belt it is rumoured to maintain a clandestine technology museum that would rewrite a few history books and no doubt fascinate the Hackaday readership.

Perhaps the most famous of all its secrets was the wartime Colossus, the first all-electronic stored program digital computer, which took an unauthorised book in the 1970s to bring to public attention. Otherwise its historical artifacts have been tantalisingly out-of-reach, hinted at but never shown.

A temporary exhibition at the Science Museum in London then should be a must-visit for anyone with an interest in clandestine technology. Top Secret: From ciphers to cyber security occupies the basement gallery, and includes among other exhibits a fascinating selection of artifacts from the Government agency. On a trip to London I met up with a friend, and we went along to take a look.

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