It’s 1963, the height of the Cold War. Safely out of sight and earshot, an international espionage agent sits furtively huddled over a short-wave radio, listening intently for strings of seemingly random numbers. Despite the high levels of static interference, they’re painstakingly written down, one by one, and later tabulated against a ‘one time pad‘ to reveal, letter by letter, the spy’s new instructions.
Scroll forward fifty years to 2013, when gigabytes of über-encrypted data might be transferred to an agent in a mouseclick – making the so-called ‘number-stations‘ seem anachronistic to the point of comedy. Odd then, that a number of the world’s superpowers (and some not-so-super) are still routinely using them.
And whoever chose the traditional English folksong ‘The Lincolnshire Poacher‘ as the call-sign for the now-famous number station known formally as ‘E3’, [click the pic to listen, .mp3 format] definitely had a well-tuned sense of humour. Poaching being an illegal, clandestine activity. As is high-power broadcasting on a protected waveband without a valid licence. As is, many might say, espionage itself.
Extensive details about how the numbers stations work were published for the first time in the journal Cryptologia Volume 31, Issue 4, 2007.
Amateur (de)cryptologists who fancy trying their hand at illegally* intercepting what is itself an illegal activity, might well use the impressive broadband online radio tuner provided free by the University of Twente in The Netherlands. The stations typically only appear for half an hour or so, and sometimes only on a designated day-of-the-week. Details of dozens of stations can be found here [search for “numbers”] And those who wish to listen-out for the infamous ‘Lincolnshire Poacher’ (should it reappear) will find the last-known transmission schedule and frequencies here.
* Note that simply ‘intercepting’ government messages which carry ‘secret’ information (even though in this case they are broadcast to the entire world, and despite the fact that you can’t decrypt them) is deemed illegal in several countries.
BONUSES
● Many more number station recordings can be heard here:
● A video showing an a-capella choir quartet of ‘Speech/Morse Generators’ (as formerly used by the STASI &etc) performing in unison.