It is a measure of how things have changed that 100 years ago coders were mostly covert state employees at organisations like the Government Code & Cypher School, the forerunner of GCHQ, which was set up in 1919 but whose existence was barely acknowledged until the Eighties.
Today, coders are the backbone of the world’s most famous and valuable companies – Microsoft, Google, Facebook. And we are encouraged to get our children coding as early as possible so that they may shape the world – not have it shaped for them.
Secrecy has become so public that it forms the sales pitch of smartphone apps that offer “end-to-end encryption” – all the way from your device to your interlocutor’s, no matter the intervening infrastructure. Messages are locked up with keys 256 binary digits, or bits, long. The machine that encoded instructions to field officers based on the Enigma intercepts, information so secret it was known as “ultra”, had just five.
That machine, 5-UCO, is one of the exhibits at Top Secret, a new exhibition at the Science Museum that plots the evolution of encryption from the state to the private sphere.
Liz Bruton, the show’s curator, says it aims to convey the “past, present and future of communications security” and the “life-and-death importance of concealing and revealing the contents of messages”. So there is the inevitable shiver down the spine that accompanies any close contact with an Enigma machine.
There is also the secure telephone that Margaret Thatcher used to discuss rules of engagement with the MoD during the Falklands War. And that is the moment, Bruton suggests, at which Britain’s coders started being winkled out of their hitherto secret realm. For it was during the Falklands that our reliance on American satellite intercepts was tested to destruction, leading to the decision to commission Zircon, a spy satellite of our own.
But Zircon was discovered and a BBC documentary planned, then banned. The rumpus, as the Cold War drew to a close, forced GCHQ out of its shell, at least a little. It has never fully gone back. Recently, it even produced its own book of puzzles.
Indeed, so public is GCHQ these days that the top of its website now appeals for recruits, knowing as it does that it must compete for talent with Silicon Valley’s finest. It certainly cannot compete with West Coast salaries.
Whether public or private sector secrecy, many of the skills are interchangeable because the function of coding remains essentially the same – wrapping and unwrapping parcels of information. Indeed our anxiety about tech companies today hinges on the discrepancy between the two; between the overt, outsized influence they have on our lives and our ignorance about the methods – the code – they deploy to do so.
Such is today’s battle in the war between encryption and decryption, which has laced the history of coding.
Perhaps, as it sometimes seems, we will be content to entrust the internet with everything from our finances to our love lives, unconcerned by how the coding wizardry going on behind the curtain is harvesting and scrutinising our personal secrets.
But as growing public disquiet suggests, and this exhibition confirms, there has always been pushback. In future, we may be more protective of our secrets, and want to know more about those who seek access to them.
Five of the 20th century’s most innovative devices
The Fullerphone (1916)
Until a century or so ago, secure communications could sometimes seem like an afterthought for military planners. One item in the Top Secret exhibition – a Crimean-War-era codebook – was made at such speed following British deployment in the wake of Russia’s destruction of the Turkish Fleet in 1854 that it contains just 2,000 words, phrases or sentences.
By the Great War, things had not improved much, with critical intelligence on battle plans discussed on trench telephones easily tapped by the enemy. German soldiers intercepted plans for the notoriously bloody Somme offensive in this way. Only afterwards was the Fullerphone introduced, modifying telephone signals to render them far harder to plunder.
5-UCO ( 1943)
What makes the 5-UCO so fascinating, apart from the fact that it is on display from the first time, is that it exemplifies the idea that intelligence is nothing unless you can use it. The decrypts of the Enigma machines at Bletchley would have been useless had there not been a method of transmitting their findings securely to field commanders. 5-UCO, developed in 1943, was that method, a large, unwieldy piece of kit so secret that it was long thought to have been destroyed to conceal the very fact of its existence.
In fact it survived the war, and continued to be used successfully into the 1950s in Commonwealth and Nato communications. 5-UCO stands for 5-Unit COntrolled - a reference to its 5-bit circuits. Bit composed from the words binary digit. The more bits used, the exponentially more difficult it is to crack codes. Today, 128 or 256-bit encryption is usual on smartphone apps.
The Pickwick phone (1960)
If any item serves as a reminder of the stakes in the Sixties, it is this. Pickwick was the name given to the transatlantic communications system established to keep John F Kennedy and Harold Macmillan in contact during the Cuban Missile Crisis. But documents now in the National Archives describe the installation of Pickwick units across government departments in 1960 and 1961 (if you got one, you were undoubtedly important. So they were status symbols of the time). The phones worked by routing calls through cipher units that mashed up the speech, thus preventing eavesdroppers from understanding what was being discussed.
Foreign agent radio set (1960s)
Probably the single most evocative item in the exhibition. So many encryption and decryption devices reveal the vast power of the state – huge machines developed in military complexes. But this radio set represents the other end of that espionage relationship: the solitary agent in the field, operating under secrecy and stress, at constant risk of discovery. Who knows under what circumstances it was jettisoned by a Soviet military intelligence (GRU) officer in a field near Aberystwyth in the early Sixties? Who knows what secrets, stolen from Britain at the height of the Cold War, it relayed to Moscow?
BID Brahms 470 secure telephone (1981)
From Pickwick to Brahms – the critical evolution in the 20 years from 1960 to 1980 was that top level secure telephone systems became portable. This item led directly to the sinking of the Belgrano in the Falklands War in 1982, when Margaret Thatcher used it to discuss matters with the MoD. If possible, it has an even greater significance, however, in that its portability pointed to a world in which highly secure, encrypted devices would become small enough for all of us to carry around in our pockets.
And that is what has happened, as smartphone and app manufacturers rival each other to boast of end-to-end encryption for private messaging that was – only very recently – the preserve of the most sophisticated governments.
Top Secret is at the Science Museum from July 10-February 23 2020. Details: sciencemuseum.org.uk