Facinating but it stopped just as he was explaining the flaw, where's part 2?
Simon Singh's book "The Code Book" is a history of code making and breaking. Besides teaching rudimentary cryptanalysis, it contains an excellent discussion of the Enigma machine and its failings. Most of them were operational. For example they only used one key per day and had boiler plate text in fixed positions within the messages. This greatly reduced the security since the allies knew what certain blocks of text were supposed to say. These footholds in the plain text are called cribs by cryptanalysts.
However, Enigma's greatest vulnerability was that each symbol make two trips through one of the encoding stages. This didn't seem too bad to its creators, but it was a critical flaw with respect to double letters which in effect sent one symbol through the machine four times! This produced patterns in the cipher texts which could predict what the daily key was.
Update: I went back and read up on the flaw again. The two trips through the machine meant that a letter could not encrypt to itself. So a repeated letter can't encrypt to itself twice. Now imagine that I keep typing the same letter over and over again. I can figure out what it is based upon the one letter not in the cipher texts. Given that the Nazis use the same key all day long, with boiler plate text, we can begin to exclude certain rotor settings based upon what isn't in the cipher texts.
This didn't seem too bad to its creators, but it was a critical flaw with respect to double letters which in effect sent one symbol through the machine four times! This produced patterns in the cipher texts which could predict what the daily key was.
The one and only time they sent the word "bookkeeper", their triple double letter jig was up!
What's interesting is that rotor machines like the Enigma (without the flaw) were still state of the art until the 70's The problem with symmetric key cryptography is key distribution which is creates a point of attack. During the 70's computers reached a level of computational power that allowed the use of public key cryptography, so it became state of the art.
I'll put in another plug for "The Code Book" which describes the true history of two key cryptography, one time pad cryptography, and Quantum cryptography which is the current state of the art.
This flaw (the letter was never encoded as itself) plus several others, including procedural mistakes, were detailed very well in a 1970s BBC "programme" The Secret War. (Those Brits are so funny with their high-falutin' spellings!)
In fact, some of the description the presenter uses in the YouTube video is very similar to William Woollard's narration in the old TV show.
In any case, I highly recommend this series, which spans six one hour episodes (a seventh was added later), and also details such things as the V1 and V2 program, magnetic mines, and radar. I'm not aware if it's on DVD.
I presume you are joking... There's a room at Bletchley Park with the real story of U-571 postered all round the walls.
Sure I was. Never trust Hollywood to let the truth get in the way of a good story.
BTW, from Wiki: U-571 was the name of the eponymous U-boat in U-571, a movie released in 2000, starring Matthew McConaughey, Bill Paxton and Jon Bon Jovi. The real U-571 was never captured by the Allies, nor was her Enigma Machine ever taken. The events in the film are loosely based on the British capture of U-110 and her Enigma and cipher keys.
The real U-571 was never involved in any such events, was not captured, and was in fact sunk in January 1944, off Ireland, by a Short Sunderland flying boat from No. 461 Squadron, Royal Australian Air Force.
BTW, from Wiki: U-571 was the name of the eponymous U-boat in U-571, a movie released in 2000, starring Matthew McConaughey, Bill Paxton and Jon Bon Jovi. The real U-571 was .
I met Jon Bon Jovi when he made his first appearance on TOTP, he was looking around the studio during rehearsals filming with his little camcorder and stopped to tell us a joke which cannot be repeated on a family forum.
@Phil thanks for the link I can now carry on watching
We were using machines that looked like modern versions of that Tiger calculator in technical college to learn some numerical analysis on in the mid 1970s. It's quite a treat to get square roots out of those things.
erco
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You discovered the numberphile channel on YouTube, isn't it great?
Be sure to also check out the maths rants by vihart and then sixtysymbols.
That's what has taken up most of my Christmas holiday!
But not yet surpassing the number of McDonald's hamburgers sold...
To quote the description on YouTube: "More on Enigma coming soon, including its flaw which was exploited by the allies."
[ Incidentally James (who's giving the talk) comes to our local juggling club sometimes (Cambridge UK)... Its a small world ]
Simon Singh's book "The Code Book" is a history of code making and breaking. Besides teaching rudimentary cryptanalysis, it contains an excellent discussion of the Enigma machine and its failings. Most of them were operational. For example they only used one key per day and had boiler plate text in fixed positions within the messages. This greatly reduced the security since the allies knew what certain blocks of text were supposed to say. These footholds in the plain text are called cribs by cryptanalysts.
However, Enigma's greatest vulnerability was that each symbol make two trips through one of the encoding stages. This didn't seem too bad to its creators, but it was a critical flaw with respect to double letters which in effect sent one symbol through the machine four times! This produced patterns in the cipher texts which could predict what the daily key was.
Update: I went back and read up on the flaw again. The two trips through the machine meant that a letter could not encrypt to itself. So a repeated letter can't encrypt to itself twice. Now imagine that I keep typing the same letter over and over again. I can figure out what it is based upon the one letter not in the cipher texts. Given that the Nazis use the same key all day long, with boiler plate text, we can begin to exclude certain rotor settings based upon what isn't in the cipher texts.
The one and only time they sent the word "bookkeeper", their triple double letter jig was up!
-Phil
http://www.youtube.com/watch?annotation_id=annotation_509771&feature=iv&src_vid=V4V2bpZlqx8&v=BdrrJ7qd4HA
I'll put in another plug for "The Code Book" which describes the true history of two key cryptography, one time pad cryptography, and Quantum cryptography which is the current state of the art.
http://ww2images.blogspot.com/2012/12/ncr-n-530-bombe-enigma-decryption.html
And this book is darn interesting!
http://davedupre.com/2009/02/05/the-secret-in-building-26/
it was a colbration that has been ignored.
http://www.imdb.com/title/tt0141926
I presume you are joking... There's a room at Bletchley Park with the real story of U-571 postered all round the walls.
http://en.wikipedia.org/wiki/The_Secret_War_(TV_series)
In fact, some of the description the presenter uses in the YouTube video is very similar to William Woollard's narration in the old TV show.
In any case, I highly recommend this series, which spans six one hour episodes (a seventh was added later), and also details such things as the V1 and V2 program, magnetic mines, and radar. I'm not aware if it's on DVD.
Sure I was. Never trust Hollywood to let the truth get in the way of a good story.
BTW, from Wiki: U-571 was the name of the eponymous U-boat in U-571, a movie released in 2000, starring Matthew McConaughey, Bill Paxton and Jon Bon Jovi. The real U-571 was never captured by the Allies, nor was her Enigma Machine ever taken. The events in the film are loosely based on the British capture of U-110 and her Enigma and cipher keys.
The real U-571 was never involved in any such events, was not captured, and was in fact sunk in January 1944, off Ireland, by a Short Sunderland flying boat from No. 461 Squadron, Royal Australian Air Force.
Friden (Holland, 1952): http://www.youtube.com/watch?v=7S0BETniokI
Tiger (Japan,1940): http://www.youtube.com/watch?v=6LCu3b_1yVY nice internal view & mechanical demo
And don't even get me started on Babbage's 5-ton, 31-place, hardcopy-printing difference engine: http://www.youtube.com/watch?v=0anIyVGeWOI
@Phil thanks for the link I can now carry on watching
However this is the peak of pocket mechanical calculator technology http://www.youtube.com/watch?v=ZDn_DDsBWws&list=UUoxcjq-8xIDTYp3uz647V5A&index=25