We are reminded today of the passing of one of the many unsung heroes of Britain, one of those who fought without ever spilling blood; but without whom it is said that the war would have lasted another two years at least. He was John Herivel, a mathematician, cypher and coding expert, Belfast-born and founder member of Bletchley Park’s Hut 6.
He was the one man who, because he put himself into the minds and ways of the enemy, realised that they were, for the most part, just ordinary people; and because they were so ordinary, could therefore be relied upon to act like ordinary people do. In other words, most of us are set in our habits, and because we are lazy, try to do the minimum neccessary to achieve the desired result.
Herivel’s team’s task was to decipher the Enigma ‘Red’ cipher by hand, before the formidable mechanical-electronic ‘bombes’ invented by the genius of Alan Turing made the cracking of any cipher a little easier. Herivel, as I said, tried to think like an German signals operator who was setting up his machine first thing in the morning, and imagined the tired man, possibly hung-over or sleep-deprived in his first movements. The manner in which the Enigma cypher machine made its initial settings known to the recipient was dependent upon a three-letter combination, and the operator had to move the rotor and key settings according to the initial choice. He reasoned that a lazy or tired man might move the combination as little as possible, to gain some time before he could complete the rest of the setting tasks, and he then realised that, if the three letter combination was little different to the settings from the previous day, the possibilities came down from 17,576 to a couple of dozen combinations.
The speed with which the Enigma ‘Red’ cypher was broken was proven during the invasion of France, when it was guessed that the German operators were under continual pressure, and prone to making, not mistakes but moves which could more easily be guessed, and so the ‘Herivel Tip’ was proven, and history was changed forever.
He married Elizabeth Maude Jones in 1947, who died in 2005, and is survived by two daughters. Herivel; now that is a name to be remembered, as with so many of his compatriots; a story of simple genius and devotion to one’s Country; not a politician, not a consultant, but an unarmed warrior and patriot.
X-posted from A Tangled Web