Thread: More on The Enigma

A major factor in the success of the Allies from the second half of 1941 onwards was the cracking of the Enigma machine. Enigma was the name of a family of ciphering machines that used a complicated system of substitution alphabets and rotor machines which made German military transcripts almost impossible to crack by Allied intelligence. Polish Military Intelligence made the first significant breakthroughs in the 1930s but the constantly evolving system meant that it was a continuous battle to unravel this complex system. This was particularly true of the German Navy’s Enigma ciphers which had always used more secure procedures. Thus it was crucial that cipher material be captured at sea to assist in the code-breaking. The first capture of Enigma material occurred in February 1940, when rotors VI and VII, the wiring of which was at that time unknown, were captured from the crew of U-33. On 9 May 1941, the Royal Navy captured U-110 with a complete Enigma machine, codebook, operating manual and other crucial information. Naval Enigma machines or setting books were captured from a total of seven U-boats and eight German surface ships during the war. One such captured U-boat was U-505, a Type IXC U-boat captured by the USN in 1944. The U-boat was towed back to America and the crew rescued. However, to protect the secret of the capture of the vital Enigma materials the prisoners were isolated from other POWs, the Red Cross was denied access to them, and their families were informed that they had all been killed. The Enigma materials were eventually forwarded to Bletchley Park, the secret site of British code breaking operations where they helped to continue cracking German naval codes and assisted in the eventual Allied victory in the Battle of the Atlantic. Today the U-505 is on display at the Museum of Science and Industry in Chicago.

German soldiers enciphering message on an Enigma machine during World War II



Enigma machine used on board a U-Boat

These are my own photographs of Colossus, which I took during a visit arranged by the college I was attending.
It looks like an old telephone exchange because that's exactly what it was made from, but the machine shown wasn't used for communications.

The original was designed and built by Dr. Tommy Flowers and a team of telephone engineers at the GPO research station at Dollis Hill in North London. They were then dismantled and moved under great secrecy to Bletchley Park.

This is a modern rebuild of the world’s first electronic computer; called Colossus, it was used at "Station X", Bletchley Park in 1944 to break the Lorenz teleprinter cipher used by the German high command, and it helped the Allies to confirm that the Germans had swallowed the pre-"D-Day" deceptions hook, line and sinker.
Contrary to popular belief, Colossus was not used to break the Enigma code; that was the job of the "Turing Bombe", stolen code books and a couple of Enigma machines provided by the Poles, not to mention the heroic work by the teams of mathematicians. The Turing Bombe didn't actually decode the messages but was used to find the settings for the wheels and plugboard on the Enigma machine.

Between 1943 and the end of WW2 in 1945, ten of the Colossus machines were built, and they were so successful in finding the code wheel combinations on the Lorenz coded teletype machine allowing the messages to be decrypted that many bombing raids by the RAF and the 8th USAF and resistance sabotage were aimed at cutting landline communications, forcing the Germans to use radio, which could then be intercepted. At the end of hostilities only three messages were left unread, they were finally decoded using the rebuilt Colossus.

At the end of the war, Churchill was so worried about the technology falling into "Uncle Joe's" hands; the "Iron Curtain" was about to descend across Europe that he ordered a complete security blackout for 30 years and also the total destruction of all the Colossus machines, although there were rumours that parts for two of the machines found their way into storage in a basement at GCHQ, Cheltenham. That security blackout and the whole security culture of Bletchley Park was so complete that there are some stories of married couples who worked there during the war not even knowing that their spouse also worked there.

It was only after 1975 that the wartime work of Bletchley Park, including breaking the famous Enigma code came to light, by which time the whole site at Bletchley had fallen into disrepair. Thanks to the dedication of many volunteers things are looking up for Station X.

Until 1975, the US thought that they had built the first electronic computer with ENIAC, sorry, Britain did it first, and it is now acknowledged that Colossus was the first. As for films like "U571" in 2000, well as they say in Hollywood "Why let the truth get in the way of a good story".

This rebuild took one man, Tony Sale about 14 years of research and construction to piece together the machine from little more than 9 grainy pictures found in the UK National Archive at Kew, some drawings on the backs of envelopes and the memories of some of the people who worked there.

---

On the technical side, there were two types of Colossus, version 1 developed from a unit called "Heath Robinson" which contained 1500 valves, vacuum tubes to you, and version 2, which contained 2400 valves to continually read and re-read the Murray (Baudot) code 5 bit teleprinter paper tape at 1500 characters per second and apply Modulo 2 mathematics (Exclusive OR) to find a particular set of characters. Once those characters were found, the start positions for the wheel combinations indicated by Colossus were tried on a different machine called "Tunny", and if German plain language popped out then the message was then translated into English. Finding the wheel settings was made marginally easier from time to time because the operators sometimes made errors and resent messages without resetting the wheels.

The rebuild isn't just a "representation" of what the machine looked like, it really does work.
Ironically, the only place in the world where new type 807 valves, used quite extensively on the machine, can now be obtained is Russia.

If you're interested in finding out more, visit this website: http://www.codesandciphers.org.uk/

The "bedstead" paper tape transport system. The lamp for reading the holes in the punched tape can be seen in the middle of the picture. Six photocell tubes were located on the other side of the rack. Six photocells were used, five to read the Murray code and one to read the drive sprocket holes to provide a synch pulse signal.
The components shown in this picture clearly show how nothing except the concept, bedstead and circuits were designed for the job, the rest was cobbled together from already existing telephone exchange equipment; Tommy Flowers was after all an engineer employed at the Post Office Telephone Research Station at Dollis Hill, North London.
The back of the main rack showing the banks of valves, resistors, some PO "3000 type" relays, a few uniselectors and a novel cooling system.
The recreated radio monitoring site shows a BC221 hetrodyne wavemeter for accurate frequency setting and five RCA receivers type AR88, sometimes used in the "diversity mode" where a number of receivers, each with its own separate aerial, antenna to my American friends, were all tuned to the same frequency and the audio outputs were combined and the receiver AVC lines were connected together in an effort to reduce signal fading due to the atmospheric conditions which affected MF and HF radio transmissions.

Legal note:
The photographs are my own, taken by me and not reproduced from any other source.

Excellent post Brian, with some great pictures also.

I keep meaning to make a vist to Bletchley, someday i will ...

Tony Sale has my full repsect, the time on research alone makes the mind boggle...

Looking at those pictures showing the size of Colossus you can imagine it actually working during the years of WW2. Very nice post Sir.

On the direct orders from Churchill, all but two of the Colossus machines at Bletchley Park were totally destroyed, apparently to “finger sized” pieces.

The two surviving machines were redeployed to GCHQ at Cheltenham, not into storage as was first thought but rebuilt and re-instated for their original roles.
Such was the security surrounding Bletchley Park, nobody not in the immediate “need to know” circle were aware of the existence of Colossus or the methods used to decrypt the Lorenz cipher, least of all our “gallant allies” on the other side of the Iron Curtain.

Following the fall of Berlin and the end of hostilities in Europe, the Soviets “liberated” a number of the Lorenz cipher teleprinters which they thought were unbreakable, totally unaware that the UK could and in fact were decrypting everything sent using the machines. They thought that merely having the corresponding receiving teletype machine was useless without the code wheel settings, which of course it was.

The Colossus computers remained in service at GCHQ monitoring Soviet communications until some time in the 1960s.

Many of the secrets of Station X are still locked away and no doubt will remain so for some time to come, but the BBC and Bletchley Park Trust have identified some of the major “brains” behind the codebreakers, the heroes of Station X:

Alan Turing
Mathematician, genius and “father of the modern computer”. The brain behind cracking “Enigma”.

William T (Bill) Tutte
Mathematician and pattern finder who somehow managed to find the mathematics to hand decrypt the Lorenz cipher, and who in later life went on to advise RIM (Blackberry) on encryption algorithms.

Dr Tommy Flowers
Engineer. The man who along with his team at Dollis Hill devised a method to use a machine to find the Lorenz wheel settings based on Tutte’s work then designed and built the first examples of Colossus.

The unnamed thousands of people employed at Bletchley whom history will never be able to name.

They are all heroes of Station X; and of course Tony Sale who brought Colossus back to life.

CodeBreakers: Bletchley Park’s Lost Heroes. On BBC iPlayer.

Additional documents about Colossus

Originally Posted by brianw

Many of the secrets of Station X are still locked away and no doubt will remain so for some time to come

Do you believe that these secrets will ever be told Brian? If not do you have theories as to why so ...

As they say in security circles; “If I told you that, I’d have to kill you”.

Seriously, many government documents are covered by rules which stipulate how long they should remain locked. You’ve probably heard about government papers being released often in the first week of January every year. For most government matters the lock is usually between twenty-five and thirty-five years, just long enough so that the content becomes out-of-date. Other more sensitive security matters are locked away for long enough to ensure that all those people involved or mentioned in them, for example agents have died and taken their secrets with them, for instance the seventy-five year rule.

I should imagine that the seventy-five year rule would apply to some of the files from Bletchley Park, so that would mean full release in 2020/21, but for the stuff which went on with Colossus at GCHQ, well that’s at least after 2035, but who knows? GCHQ have always been a law unto themselves.

I’ve no doubt that some extremely sensitive documents, particularly those concerning our darker dealings with the Soviet Union during and after the war have been marked as “Never to be disclosed” and no amount of Freedom of Information Act requests are going to get to those documents to see the light of day.

Before you ask. No, I don’t have any connection now or in the past with the security service although I used to work in the Home Office as a radio engineer, where I did on occasion come into contact with some minor sensitive material.