Code breaking with Caspin

[Caspin]

I have moved this stuff out of the big General thread as it was taking up too much space!

So, here is my report on my visit to Bletchley Park, home to the WW2 codebreakers.

They chose the site for the codebreakers because it sits nicely close to London with a railway station right next door and also had good road connections. (Something I learned today - I had heard of 'trunk calls' and 'trunk roads' but only today discovered that trunk calls are so named because they are transmitted through cables laid along trunk roads.) Anyway, it's also slap-bang between Oxford and Cambridge, so they had ready access to super-brainy linguistics experts, top mathematicians and other necessary boffins. The guy who found the site and purchased it did so out of his own pocket, thinking that the ministries would reimburse him. They did not (!), but fortunately he was mad rich and could afford to buy 500 acres with his pocket change. Apart from Oxbridge brainiacs, they also employed lots of aristocrats - because they were thought to be able to keep secrets! I suppose it might be true that some of them are used to keeping family skeletons stuffed well into cupboards.

Alan Turing lived in the park but also lived, at some point, off-site. He would bike in each day on a really ancient bicycle, renowned for the chain falling off as he was going along. Instead of getting a new bike or having it fixed, he worked out how many revolutions he could pedal before it fell off, then would count as he pedalled. When he was at doom minus one, he would pedal backwards the same number, then continue. Eccentric people, these code-breakers!

What else? Oh yes, mugs were very precious and everyone would write their names on and decorate them. Mr Turing would keep his mug safe when not in use by padlocking it to his office radiator...

Where was I? Oh yes, Alan Turing and his crazy old bicycle. Another interesting thing I found out - he had terrible hayfever, with which I sympathise, so he would also be wearing his gas mask as he rode along, pedalling backwards. Must have looked a total nutter.



No bombs at Bletchley

The manor house itself is smaller than I expected. I suppose that's because they always take wide-angle photos of it. In fact, given that at the peak of activity there were 10,000 people working there, the whole place seemed too small - although of course not all of the huts are still there. They managed to be very discrete - the park didn't get bombed directly, so either the Germans didn't work out how important it was, or they just didn't find it. A few bombs were dropped nearby, they reckon because a lost enemy plane saw the railway station and decided it was a good place to ditch his bombs before heading home. Fortunately they didn't blow up anything important. This was helped by the fact that the manor house's last private resident had planted a lot of trees to try to muffle the sound of the local church's bells, which kept him awake a night. Good trees. The force of one blast knocked one of the prefab huts of its foundation but a bunch of people just hoisted it back on, without even disturbing the workers inside!

Pigeons with parachutes

One great story was about the homing pigeons that they used to carry messages home. Apparently the life expectancy for a human with the job of transmitting messages from the battlefield was just six weeks, so using pigeons must have saved a lot of lives. They would sometimes put them into little waterproof packets and then parachute them into France, for example, to be picked up by our people or by the resistance. They would then attach their messages and send the little birdies home. The pigeon parachutes were so cute! Bombers and other aircraft would also sometimes carry a pigeon on board, so that if they were shot down, they could send their last coordinates home. On one occasion they didn't manage to attach the message but the pigeon flew home anyway. His owner deduced, just by looking at his condition and how tired he seemed (?!), that he had flown 130 miles. On this basis the search and rescue team were able to rescue the pilots from the sea - 128 miles off the coast!

The wrong tea cups

So what about the most important question - did the cafe use those greeny-blue tea cups from wartime? No! Perhaps they can’t get hold of enough. They did have some mock-ups of a 1940s house, which looked an exact replica of my Nan’s house, but even that didn’t have the right teacups. I don’t know why this has become an obsession for me. I’ll work on getting over it.




OK, codebreaking, that’s what I should tell you about.

Enigma

The most well-known stories are always about the Enigma machines, which just look like big old typewriters. A guy explained how they worked - by using particular settings on three wheels and a set of plugs, you could get some mad number of possible combinations, running into billions. The Germans (and Italians etc) would change the settings every day at midnight. So even after the folk at Bletchley had deduced the settings, they were only good for cracking 24 hours worth of messages. Things must have proceeded at a frantic pace there. Brainy folk would use nothing more than grids drawn on paper and brainpower to try to crack the settings being used for that day, then they would have to break the codes and then translate the messages. After all that, some of the messages would be trivial and not be useful. I don’t honestly think that most of us these days would have the concentration needed to do that work. Imagine being told that for the next six years you have to decipher codes using a ruler and a grid, in eight hour shifts. Given that most people’s attention span is 20 minutes. But I guess the adrenaline and knowing that lives would be lost if you screwed up were good motivators.

After a while they realised that as the war got going the number of messages being encrypted would increase and people could not keep up. They were already working 24 hours a day. So they built a machine that could mechanise the process of working out the Enigma settings. These huge machines were called Bombes and consisted of a lot of wheels with alphabets on that would spin around and deduce the possible settings. It saved time and then the codebreakers could get to work on that day’s messages more quickly. I thought it was weird that they were called Bombes, which would surely be confused at some point with ‘bombs’ and my friend and I speculated that they could be named after the continental dessert - only to later find out that we were correct. They named the machines after ice-creams!

We would have really been stuffed if it hadn’t been for the Poles. Before the war even started they had been working on Enigma machines, after realising their military potential (the machines were originally just used for encrypting private messages between banks and that sort of thing). Both Britain and France had a chance to get a machine and other intelligence but turned it down in the 1930s. Good thing Poland didn’t make the same mistake and were also willing to brief everyone else on the matter once war did begin!

We would also have been worse off if it were not for the soldiers and sailors who recovered Enigma machines from U-boats etc, as well as the documentation. If you could recover a sheet of settings from behind enemy lines, you could have the Enigma settings for the next month!

Well done to anyone who’s still with me. There will be a test at the end (not really).

Colossus

The thing that impressed me most, though, was not the cracking of the Enigma codes but the cracking of Lorenz codes. It’s so impressive because of the sheer complexity of the code but also I loved it because the whole thing was essentially started by a policeman and finished by someone from the post office.

The Lorenz machines were used by German high command - so Hitler would use them to send top secret messages to his chiefs. Like Enigma they looked like massive typewriters (actually they looked to me like ye olde cash registers). They were much harder to crack, though, because unlike Enigma’s three wheels and a bunch of plugs, Lorenz machines had twelve wheels, leading to a stupidly huge big number of possible permutations. They also changed the settings not every day but after EVERY message! It sounds impossible to crack, right?

Britain only became aware of the existence of these messages being sent because of a policeman listening to the airways, scanning for anything interesting and coming across a strange series of pips that were too rapid to be morse code. Well done that copper! To record them they used a Victorian machine called an undulator (lovely name and well done the Victorians!), which would record the sounds as a squiggly line. Then they would ‘translate’ this line onto ticker tape on a teleprinter, as a series of punched holes. Unfortunately that’s as far as they got, at first, as it was all enciphered gibberish. So they had all these paper tapes of important messages from Hitler and no way to read them.

Fortunately one day someone made two big mistakes. Some poor German guy sent a really long Lorenz-encoded message. The message was so long they reckon it would have taken him about 1.5 hours to transmit. Then the receiver informed him that because of bad atmospherics, he would have to re-send it. Mistake number one: he should have changed the settings but decided not to, presumably because it was a faff and he was grumpy by then. Mistake number two: he used abbreviations to shorten the message, again because it was so long and he was grumpy. Luckily for Bletchley, this meant that they suddenly got hold of two tapes that used the same Lorenz settings (which should never have happened) but with tapes of different lengths, because the second message was shortened. Some braniacs locked themselves away for a few weeks with pencils and squared paper and deduced not only (without ever having seen a machine) that the Lorenz machine used twelve wheels but also cracked how to decode it. They showed us the diagram the boffins drew and it was as though they had been given the machine and drawn a schematic of its workings, bloody amazing.

Don’t worry I’m nearly out of facts. They built a sort of machine to work out Lorenz settings based on this knowledge (bearing in mind that there were new settings for every message) but because it had to read those paper teletype tapes, it was so unreliable and frustrating to use. The tapes would snap or stretch or get out of line. The machine was so fiddly and patched they called it Heath Robinson. They were able to translate the messages eventually but sometimes only six weeks after receipt, which is no use at all during a war.

Luckily a clever chap called Mr Flowers, who worked for the Post Office, designed Colossus for them, a huge beast of valves and wires and light-bulbs blinking on and off. It was the first programmable computer. There were spools (like you put old films on) to spin the paper tapes round at 30 mph. So they would stick a tape in Colossus and it would decode it automatically. Well done Mr Flowers! They have a replica at Bletchley up and running and if you are interested in early computers it’s quite a sight!

That is all.

[Minty]

Brilliant post!

I'd never heard of the Lorenz machines - I thought all the Germans used was the Engima ones. Will have to investigate this further! I remember reading about the sailors who drowned jumping into an abandoned submarine in order to get an intact Enigma machine because it was worth more than all their lives put together to stop the Wolf Packs singing millions of tonnes of shipping.

Why doesn't it surprise me to learn that the British government didn't reimburse the guy that built Bletchley? They stitched up Flowers as well - tried to throw him off the project at one stage for "wasting resources" when most of the bits & pieces that went to make it had come from his own salvaging or out of his own pocket! We dish out gongs to gonks & real heroes & heroines are forgotten.

Random German bombs were a common hazard in WW2 over Britain. The unspoken rule of thumb for any nazi plane on its own was if it came under attack or was about to be they were to jettison any bombs or wing pod fuel tanks they had to stand a better chance. Robert Stanford Tuck got his sister's husband killed in this manner when he attacked a stray Heinkel & it jettisoned its bombs over his sentry post. Another problem was the early bomb cradles in German bombers stood the bombs upright, & occasionally the bombs would stick when they tried to drop them. They daren't bang the top of the stuck bombs, in case the bombs went bang - so the navigator would desperately push on the exposed parts of the bomb that could be reached trying to get it loose & trying not to lose any fingers in the process.

Result, random bomb drops, one of which allowed what would have been football's first major fraud and tax dodge scandal to go unpunished. One hit King's Park football club's Forthbank park in Stirling. The damage wasn't much (they played further matches until they were mothballed for the duration of the war by the authorities - this happened a lot in Scotland), but after the war the owners used this as an excuse to fold the original club & start a "new" one at a new ground - Stirling Albion - to thwart held over investigations into illegal under the counter payments of players (rumour was they were paying the biggest wages of any British football club via owner & local coal magnate Tom Fergusson, but not according to their accounts!).

Pigeons with parachutes! It's like something from Allo Allo!

[Caspin]

I know, you couldn't make this stuff up! Those pigeons had some adventures, that's for sure.

Yes, they told the story of the guys who went into the sinking submarine to get the Enigma. Incredible people. One of those who survived and brought back some of the papers was only 16 - he'd lied about his age when he enlisted.

What is also incredible that everyone involved kept their mouths shut, even afterwards, to keep the park's secrets as they'd promised. Nowadays it would be all over FB in about ten seconds! You can imagine someone posting a picture "here's me cracking Enigma" and then their 500 'friends', of which they've met 15, would 'like' it.

I must go back some time - the ticket lasts a year but I wouldn't begrudge them another entrance fee, there's so much there that needs to be preserved - as the National Museum of Computing was closed for a school group and it looked really interesting. Plus there are some exhibitions of the museum that I need to study again to absorb. There was bit on spies and double-agents that I didn't even get to - and I bet that's interesting!