The Enigma Code

An elementary introduction to the way the famous Enigma code used by the Germans during WWII. David Perry explains some of the history and the mathematics behind the code.
This is part of an outreach program
sponsored by NSF-VIGRE at UC Davis.

[@billdomb]

There are LOTS of lectures/vids on Enigma, but this is the BEST to understand the real decoding process.

[@uiscepreston]

This guy is a trooper, holding his tie up for an hour.

[@richardball8365]

Cryptologic mathematician at the NSA. Clearly very clever indeed. But doesn't think to simply clip the microphone further up his tie. It's interesting how great minds work!

[@frederickbowdler8169]

Or take a hammer to the enigma we should just have jammed German radio from beginning of the war with cheap jazz music drive em crazy.

[@WJack97224]

Excellent talk. Thank you David Perry. Good on ya mate. And thanks for posting this lecture.

[@jimbond8927]

This is quite helpful. I have read and seen a great deal about the cracking of the Enigma; this video helped me to understand the challenges and the breakthroughs of Turing and his colleagues.

[@cumberland1234]

Brilliant explanation, I have wondered for a long time how these machines work, most videos I’ve seen don’t go as in depth. Thanks for uploading.

[@kupfeli]

This is an awesome explanation! Only things missing (which are important details) are the ring-settings which determine when a rotor steps and the double-stepping mechanism. A normal odometer triggers the next ring after it gets to zero again, so at the 10th click (starting at 0). Using the ring-settings of an Enigma rotor you can change when this triggering of the next rotor starts, which makes for even more combinations. Apart from that we also have something called double-stepping which is a flaw of the mechanical setup of the rotor rotation mechanism using ratchets and pawls. When the second rotor rotates a click, the first one will too and the same is the case for the third rotor (near the reflector), so basically there are a few ring-settings less (for instance: if the second rotor steps, the first will too, but that means the possibility of only the second rotor is stepped is not there DURING encryption. In initial setup that setting is there). You need to have an actual Enigma mechanism to understand this. The number of non-used ring-settings is very small, so you can basically neglect it, or maybe not? Maybe, you can even find out the ring-settings because of this double-stepping flaw. Each flaw is a potential attack vector. I love the Enigma and basically all mechanical encryption devices. I dont like digital encryption, for the sake of liking a specific type of technology. Digital encryption is mechanical too in a sense, as a switch is an implementation of an abstract mechanical principle basically, a seesaw mechanism. As a transistor is a switch, we can conclude that a processor is mechanical. The fact the seesaw mechanism is driven by electrons and doesnt make it any different. Wait for quantum encryption where we really have non-mechanical concepts, like a situation where a switch can simultaneously be in a on and off position, this is not possible for an abstract switch definition being either on/off, hence our current computers are simply fast mechanical systems and the real next leap and change is quantum mechanics (where as I stated, mechanics is not a correct term, I would use quantum system for instance).

[@Tsynique]

There was one more variable in the Enigma. The operator also had to set up at which rotor position would it advance the next rotor. Not necessarily Z moves the next rotor but maybe A or G, etc. Maybe that was in one of the improved versions of the Enigma but either way it added a whole lot more keys to it.

[@BuddhatheBlackDog]

Good job David Perry.

[@cooldawg2009]

This was amazing, thank you so much. And thanks for keeping the mood very light, it made your explanations that much easier to follow

[@asd36f]

The Powerhouse Museum in Sydney has an Enigma machine, and 20 odd years I was able to visit the storage area and have a closer look at it - as a WW2 buff, it was a great thrill!

[@Varianna12]

Super course! Have been waiting for this.

[@adriaansmit4389]

I thought he was joking when he said that he would be going to hold his tie up during that whole lecture

[@LightningJackFlash]

Hahah I thought that too :) But then he actually does that throughout the whole lecture :P Isn't that sweet of him? :P I watched this for the first time in 2010.... It had about 1000 views then. now it's 1/3rd of a million.

[@Torchl146]

bro didn't you listen hes a cryptologic mathematician he likes complex solutions and doesn't live in the real world that much :D

[@Drokuz]

Awesome video, it was very well explained. Thanks for sharing!

[@KipIngram]

Oh man - you didn't even mention the other big weakness: no letter can ever possibly map to itself. That was very important too.

[@alanthomas8836]

The U-571 mentioned and listed on the board was the name of the eponymous U-boat in the movie released in 2000. However 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.

[@carpy1970]

Also completely missed out that the Polish only managed to crack the German army and airforce enigma transmissions (they couldn't decrypt navy transmissions), and that their methods of cracking it become unusable 6 months later when the Germans changed their encryption procedures. While Turing and the British did gain information from the Polish, they created a new method of hacking the transmissions that was useable to decrypt German navy transmissions and also still worked after the germans changed their procedures. I guess this is the usual case of mericans wanting to gloss over the fact that the british had much to do with WW2 at all......

[@cirrus1964]

How did Turing decode messages before these codebooks where found? As far as I understood, these books only confirmed what they already knew.

[@staninjapan07]

Thanks very much, I thoroughly enjoyed that.

[@camieabz]

Non-mathematician. Zero interest in (typical?) algebra, never mind abstract algebra. That guy made things interesting enough for non-mathematicians to grasp. Good talk. +1

[@localbod]

Thanks for sharing.Very informative.

[@Rachel-Pham]

ive been recommended this for a reason

[@won20529jun]

Great lecture!

[@PuI2ePLaYaZ]

one of the greatest minds in cryptology... but couldn't "decrypt" the fact that If you took a minute of your time to move the mic will save you the rest of the lecture holding it in place

[@tyraelarchangel183]

That's more a stubborn/awkward thing. He probably felt too awkward to move it, after he'd already held it up for a minute or so. By then it would be really awkward to just move it 20 minutes into the lecture. The stubbornness comes from not caving in to the awkwardness. It's kind of like if you go to a drive-thru, and the line seems long. You may say "I should just go somewhere else", but you decide from stubbornness/laziness to wait. Well, now you've been waiting for 2 minutes and still haven't moved. Is it too late to just get out of line? Well, you'd have to wait until you get a few spots ahead to actually pull out (maybe you're blocked in now). By that time is it worth it? After all by then you've moved up a bit and can now order at the speaker........ but the line is still going so slow, it still may just be faster to go somewhere else.... but you already have so much time invested in it.... do you stay? Who know after you order the line may go fast... but judging from the information you already have, it's not. But after waiting 20 minutes in line is it even worth it anymore to go somewhere else? If it would only take 10 min to go somewhere else that would be better than waiting 20 more minutes in this line.... but we don't know how much time is left, or if the place we want to go will even be that fast! So in the end you, and most people, just wait it out. If you decide from the get go (i.e. before you really get into the line) to leave, that's different. I've done it, a lot of people have done it. But I've also done the above where I know I should leave and cut my wait time, but I'm too stubborn, lazy, and don't have enough information (who knows if the other restaurant isn't just as busy), and I just wait for an eternity... It's kind of like that. Logic dictates X, and most of us would choose X given enough time and knowledge. But in the moment, without knowing exactly what's going to happen, or not caring right then, we instead just keep with Y instead of changing to X.

[@dozog]

The problem is not only how far up the microphone is. If he pulls the microphone higher, he places it closer to his mouth, but also more into the "shadow" of his chin. Notice when the lady uses his microphone. She has to be almost perfectly in front of the mic to be amplified.

[@dozog]

Part of what you re talking about is called "sunk cost fallacy". The speaker moving up the microphone is different because if the higher position works, there is no ambiguity about having made the right decision. Awkwardness may have been part of the reason he kept with his chosen strategy.

[@sau002]

Excellent video

[@papoocanada]

@Channellock12 the best - and slower and complicated - was the One Time Pad. The rotored Enigma was improved to become the Type X machine with 5 rotors and plug boards. Then, the Rockex machines, one regular tape en clair but coded by a second tape. Today they mostly use a sort of teletype with scramblers.

[@KipIngram]

There were actually five rotors in the early Enigmas - you picked three from the five. So you had 5*4*3 = 60 ways of doing that - not just the six you'd have if you were just ordering three rotors. Later on it went to eight, with three chosen. And the German Navy added a fourth rotor.

[@ZanagKraun]

@Channellock12 I believe it was a machine called the M-209 and a lot of Navajo code talkers..

[@agentdark64]

4:00 That's exactly the level of encryption you get with the enigma IF and only IF you only need to worry about the plugboards and you have correctly worked out the rotor settings. And only having to work out the rotor settings reduces the amount of combinations for brute forcing. If you know part of the plain text, you only need to work out rotor settings where the letters come out the same as each other respective of where they are the same in the plain text message. For example, if the message is always known to start with hello, then you know a good chance letter at position 3 & 4 should be the same after the correct rotor settings and there is only like 17576 rotor settings to go through which is possible brute force using modern computers today.

[@MrDaiseymay]

I think his casual tone---seems to imply, that the Enigma machine was nothing to be in awe of. In other words, he's basing his views and attitudes from the perspective, that 75 years of advance and improvement has been gained. FROM THIS AMAZING MACHINE.

[@MarKiv987]

Any one have idea wer to find the second part this lecture?? I'm really looking for more insightful video on how enigma was broken...

[@roncarney9158]

That bloody tie! Why didn`t he just move the mic higher?

[@granskare]

I was in Turkey 1957-1959 and Det 3 was the unit that worked with NSA, I was just a support person.

[@DutchManticore]

@SacredSocietyAP It's something a lot of teachers do. Teachers at my university also mess around with their microphone/mic.clips all the time.

[@daftpunk3401]

Great video and I searched for more but unfortunately couldn't find any other David's materials, even if he did some cryptology lecturing years ago.

[@JimTLonW6]

Very interesting, and it does, at long last, answer my question why a letter couldn't cipher to itself.

[@matambale]

@5:02 Error: both K and H translate to Y in his solution. Guessing that there is a typo, and 'XH' should have been 'XK', or that 'CYCIK' should have been 'CYCIH'

[@b43xoit]

The movie _Das Boot_ also depicts the use of an Enigma machine.

[@ChrisOBrien666]

Very interesting video but neglects to mention an extremely fundamental flaw in the Enigma machine that helped in breaking it was that a character can NEVER be encrypted to itself.

[@cluxseltoot]

I would have liked to have asked a question about different cultures and the messages sent - were any of them frivolous or just plain communication? EG: Did they send salutations or gossip?

[@petermostyneccleston2884]

In one of the books about the work going on in Bletchley Park, it mentions that it was possible that the code breakers knew about the Blitz on Coventry, but no more than four hours prior to the attack. It is unclear in that book, which city was to be bombed. Another source said that the Airforce codes meant that the code for London, was exactly the same as for Oxford. This is another reason why the British did not react, as it was likely to be unclear which city would be Blitzed in under four hours. I have not seen any sources which say that anyone had found out, or if they had not. There is however evidence that the code breakers of Bletchley park, kept information away from the Admiralty, and were choosing which of the convoys to allow through, and which ones were allowed to be attacked. This was purely to let the German military think that the British have not cracked the Enigma codes.

[@Eric-ye5yz]

How did the information deciphered get distributed with out getting cracked ..... what encryption did the allies use to share the information?

[@leoschrickel611]

There actually was a mistake/typo in his initial puzzle as the symbols representing Y in the solution were shown to be both K and H

[@brown3394]

it was UP not BY. "can attain UP remaining on the level" is the only possible answer that makes sense.

[@jimbob1427]

Interesting talk 👍

[@DinHamburg]

are there other videos with this guy ?

[@ZER0--]

58:00 There were machines with have eventually 10 rotors.

[@RedcoatT]

In the attack on Coventry, the British were aware that a major attack was going to take place, but the code name used to identify the target was unknown, so a general warning went out, placing all of the civil defence on high alert. However the claim that the British might have evacuated Coventry if they had known it was the target is nonsense, no town was ever evacuated because it was under threat from bombing. The British had already evacuated all the women and children from the major towns who were willing to go, any further evacuation would have impared the war effort more than the bombing would have, so it was never an option

[@pedroruiz193]

59:00 Hubris turned against the nazis. They NEVER considered their Enigma cipher could have been broken. They would explain it every other possible way except the cipher being broken every day a couple of hours after 7:00 AM. Credit goes to the Polish mathematician that found an ALGORITHM to break Enigma. An algorithm means that it is not brute force (trying out every possible configuration of rotors, plugboard, etc....) but a shortcut that reduces drastically the number of possible configurations to be tried out. But the Polish mathematicians stopped there: they didn't know how to implement the algorithm they had discovered. Even if it was a shortcut, it was still too many calculations to be done manually, even by hundreds of people crunching numbers with pencil and paper, in an efficient way (before the nazis changed the configuration every day at 7:00 AM, only 24 hours from the first intercepted message to find the configuration for that day). The credit for inventing an electromechanical device that could implement the Polish algorithm and find the configuration in a couple of hours after 7:00 AM goes to Alan Turing.

[@memonic1]

Read about Rajewski's cryptographic bomb that enables the automation of Enigma decryption :)

[@fritsvanzanten3573]

Can we see part 2 somewhere?

[@iprice77]

Going over a bump and the CD continuing is not error correction, its pre-buffering. Reading over a scratch in the optical media is error correction :P Bouncing the laser way off the track isn't error recoverable because you cant read the error recovery data either :P

[@rods6405]

Yeah he got that wrong!

[@florianritter7871]

Could it be “vigenere” this 8-letters on 21:48?

[@rlingren]

Its interesting that no one asked how they made a space or sent numbers or Lat and Long. Obviously it is easy with a full typewriter keyboard, WWII technology, I can think of several ways to encode numbers and symbols like ° ' " . but all require sequences of letters that are in aggregate much longer than the numbers they replace. It seems really inefficient and they were all about efficiency, and does anyone know why the 4 letter spaces 4 letter spaces sequence ? thanks

[@patbates3835]

WE USE TO SPELL THE NUMBER IN TEXT FORM IN THE ARMY

[@rigomiller6524]

h and k both = y in the cryptogram example at 5:45

[@frederickbowdler8169]

Surely when you press A a switch is thrown which blanks out the A light bulb and that is why an A never translates as A. Am I correct.?

[@mike94560]

So... How did they do numbers? I would not want to put Lat/Long in plaintext. And spelling it all out seems odd.

[@HeatherWalt]

Would have been great to compare the enigma code to other coding platforms that existed back in WWII.

[@KipIngram]

Well, you didn't mention that the visible ring on the rotor could be adjusted by an offset relative to the wiring. The visible ring controlled when the rotor turned over its neighbor, and the wiring was independent of that. The offset for each rotor was also part of the daily setup. And, you didn't mention the double step. I guess it's not really that important - it weakens the code space size a little, but it's not really germane to understanding how the thing works. But in fact it DOESN'T work exactly like an odometer. The offsets, though, were important - that added another factor of 26^3 to the size of the configuration space.

[@LightningJackFlash]

I remember watching it for the first time in 2010, when it had about 1000 views ;)

[@Trifecta3x3]

Most of these views came after the movie "The Imitation Game" which inspired people's historical curiosity.

[@James_Bowie]

@@Trifecta3x3 ... and that movie was 50% bollocks.

[@lqr824]

40:11 "There aren't going to be messages longer than..." But in a single day there might be several thousand messages encrypted with the daily cipher, no? Does that not suffice to use letter frequency to figure out what the daily setting's first letter's map is? That should give you enough letters to get the frequency counts you need to simply approach statistically? Granted, for further characters positions we'll have fewer and fewer messages with so many characters, but why weren't at least short messages broken this way? (Or were they?)

[@Jasooonthemachine]

I don’t think it would have been possible to apply frequency analysis on messages sent on different machines on the same day as each machine would have had a different key. The key is the main defence against frequency analysis.

[@lqr824]

@@Jasooonthemachine How would each message have had a different key? The recipient must know the key in order to decipher. A key based on the date would be the same key for each message. A key based on time could vary more but make retransmission require a complete re-encoding. I'm no expert but the impression I got is that a book said on date X/Y/ZZZZ, you use rotors 1 3 5 8 9 at positions d n e o d, and for each message you must reset to that starting point??

[@rustycherkas8229]

The "Gov't issue config settings for today" (that water soluble ink stuff) tells ALL operators how to initially configure the machine each day, all day... Each operator, for each message(!), must think up 3 "random" letters. The operator encrypts those 3 letters (twice) to get a string of 6 encrypted letters. The last 3 of those are ignored for the moment; the first 3 are the "key" to decrypting the message. Operators were instructed to NEVER use the same key twice when encrypting (especially re-encrypting) any message. Some did, some didn't... The operator sets the rotors to match those first 3 letters... This is the "encryption seed" for the machine to encrypt this one message by lighting indicator lightbulbs whose values are the "cyphertext"... The radio transmission (morse code) of the cyphertext would be prefaced with those six (encrypted) letters followed by the cyphertext. The listening British can write down all the cyphertext they receive and KNOW that those first 3 letters are the key to decrypting the whole message... but, what were the German's "daily configuration" settings that encrypted those 3 letters from plain text??? If the British knew those configuration settings for each day, they'd be mirroring exactly what the intended German receivers would be doing... But, the Germans didn't share each days settings with the British, leaving only 10 quadrillion possibilities to try...

[@jasonguyperson]

I can't believe he held his tie that long.

[@papoocanada]

we were still using all of them as late as 1970 in Canada. Typex was fun, so noisy , bang bang bang. 10-4 nnnn

[@franzbernasek4058]

Great , Super

[@jbalmyetsh7095]

There is a flaw in the Cryptogram as CYCIK is either CYCIH or XH should be XK

[@fritsvanzanten3573]

Yes, the Y is encrypted as H as well as as K (hm, this sounds weird). Funny/tragically enough in many a text or video about cracking Enigma there is a crib 'Keine besonderen Ereignisse' that is spelled as 'Keine besondere Ereignisse' , without the 'n'. One starts to wonder.... I hope Alan Turning wasn't plagued by this.

[@bonbonpony]

05:36 I solved it before this point, but It bothered me why is "Y" supposed to be encoded by two different letters: "H" and "K". Looks like some kind of a typographic error to me :P

[@BunnyFacedAssasin]

i fucking wasted 15 minutes cause of that shit.

[@mrewan6221]

I found that too, and assumed a mistake was made somewhere: either the original encrypter, the typesetter, or the presenter.

[@brown3394]

the real answer to the puzzle is "man can attain UP remaining on the level"

[@dylanwhostones]

No but that was mid 1943 nearly 3/4 of the way through the war. The Germans always had access to the merchant code and that told them when and where the the convoys were going....and they could always trianglulate the convoy position using the transmittions from patrol bombers and convoys.

[@SirCutRy]

What if you use the keyword's hash as the Vigenére keyword?

[@SirCutRy]

That is *exactly* what I was thinking.

[@iisagodonearth]

SirCutRy because you said it twice

[@marcinpasnicki248]

If you want to learn more about breaking the Enigma you should read XYZ by Dermot Turing

[@PreservationEnthusiast]

Too much about the Poles and the French in that. The English were the ones who did the really clever stuff!

[@marcinpasnicki248]

@@PreservationEnthusiast You are probably right after all they just built larger version of Polish bomba.

[@DraperPierce]

The British contributions to Enigma cryptanalysis are not denigrated by adding more details than in any previously-published book I've read about what the Poles did with the cryptanalysis, and certainly not the amazing story of how the codebreakers made their way from Poland to France, and then out of occupied France -- XYZ was an amazing read, and I highly recommend it to everyone who cares about the history!

[@filipdurczewski1326]

Well done Poland

[@quantumbits]

Does anyone know...since machines dont know launguage, how did Turing's machine "Christopher" know when to stop?

[@arindamchakraborty8450]

actually the machine was desgined to find the settings of a particular day. Now the rotors rotate checking each of the possible rotor settings (eliminating some of the settings as a letter cannot be encoded into itself and for other reasons). Whenever the desired settings is reached the internal circuit faces an open circuit so the electricity for the next move of the rotors is cut and the rotors , i.e. Christopher(the bombe actually, I really dont know from where the director got that name and the story of Turings' friend, perhaps to present the homosexual nature of him?) stops. By the positions of the rotors one can easyli do the rest of the job of decoding the messages, keeping in mind that theres an Enigma was available at the Bletchly Park

[@quantumbits]

Thanks. But how does the machine recognise a setting is "desired" and therefore choose to open the circuit? How could it recognise when a right character or word fit the original message?

[@arindamchakraborty8450]

It actually does not open the circuits like we open our windows when we wish. The rotors and all the moving parts faces each circuit representing each of the settings when they are rotating and as it is impossible to build 150 million^3 circuits you can understand most of the circuits was made by combining different moving parts of the machine. When ever the Bombe is tasked to find a settings it starts brute attack on the possible settings with the help of the clues inserted in the machine.Now the rotors started rotating and all the moving parts forms different circuits on each step of the rotors thereby checking the settings. The principle of Operation of the machine lies in "whenever the desired circuit(equivalent to the desired settings) is reached the combination of these moving parts will create a loophole somewhere(i.e. opening the circuit) and the conduction of current will be stopped." The mechanism was built that way. I cant explain you with further more technical details as I am just a rookie in Cryptography. Have a nice day.

[@quantumbits]

I have a feeling the movie was not quite accurate...as I am sure they did not expect the machine to find a solution without the crib.

[@eritain]

Yes, Turing's bombe was built from the beginning around the assumption that there would be a crib. It wasn't a last-hour flash of insight as dramatized in the movie. It's the whole reason the machine needs rows and rows of wheels on it to begin with. And don't get me started on "Christopher." Bletchley Park did build the first fully programmable electronic computer in the world, but it was a different machine from the bombe and neither one was named Christopher.

[@cluxseltoot]

All this intelligence yet he still speaks into his tie!

[@lohphat]

The kenngruppen weren't explained. The actual encryption key selection was more complicated and varied across military branches. users.telenet.be/d.rijmenants/en/enigmaproc.htm

[@neilonaniet]

Did nobody think to come on and adjust his mic?

[@robharris5467]

for a brilliant guy re clipping his tie higher up seems to defeat him!

[@dozog]

The problem is not only how far up the microphone is. If he pulls the microphone higher, he places it closer to his mouth, but also more into the "shadow" of his chin.

[@19shadowmaster77]

Rob Harris You have to put the microphone ahead ( in line with the sound waves), doesn't matter a lot how much closer...

[@mhern57]

Luca Gandolfo how about just unclipping it? I can't believe the host of this gathering or anyone else for that matter would let him go on without suggesting at least that. little help!

[@19shadowmaster77]

mhern57 I don't know... All i can say, is that this type of microphone are less used respect the model with a little metallic arc that goes on the side of the head. 😉

[@ANTINUTZI]

... I'm a double non-alumnus of F&M College. His confusion with microphones does not therefore surprise me.

[@rcovil]

He forgot about the Ring Settings. Each ring on the rotors was rotated too.

[@robertrannin2076]

+Ron Covil weren't ring settings a little more infrastructure, in that it wasn't a regular daily setting, more of a field modification? greatly increased permutations, no doubt.

[@clayz1]

The ring setting IS the rotor setting.

[@rexmundi2237]

Le Chiffre aka "the cipher" is the bad guy in James Bond novel Casino Royale.

[@minimushrooom]

But K and H are both encrypted as Y in the first puzzle?

[@shawn98ag2]

jqbtube in his next slide he shows that Y is encrypted to H so its a mistake. confused the hell out of me when i tried to solve it in 5 minutes.

[@hazelmira2224]

jqbtube 8uyy7

[@TheArdvaark]

The one time pad refers to coding using teleprinter traffic which is what the German Lorenz coding machine used - this was the preferred machine of Hitler and the High Command. It had nothing to do with Enigma. The Typex was the coding machine that British Intelligence used and the Germans never broke that. Although Rockex was up and running by 1943 it wasn't used in the same quantities as Typex.

[@jurjenvanderhoek316]

This guy is so intelligent ... why does he not detach the microphone from his tie?

[@WJack97224]

I read that an Enigma machine was sent by mistake to someone in Poland and it was recognized and then reverse engineered and then carefully reassembled and returned to the sender. Is that a myth?

[@patbates3835]

NO, IT IS NOT MYTH. THE GERMAN DIPLOMATIC TEAM IN WARSAW WAS WAITING FOR A PACKAGE. THEY WENT TO THE POST OFFICE OR WHATEVER IT WAS CALL ASKING IF A PACKAGE ARRIVE, SEVERAL TIMES. POLISH OFFICIALS BECAME SUSPICIOUS AND ALERTED POLISH INTELLIGENCE AND SINCE IT WAS A FRIDAY AND THE POST OFFICE WAS CLOSED ON WEEKENDS, THE THREE CRYPTO SPECIALIST OPEN THE PACKAGE, AND FOUND AN ENIGMA MACHINE. THEY QUICKLY RECORDED ALL THE INFORMATION NEED, REWRAPPED THE PACKAGE IN TIME FOR THE MONDAY MORNING SUSPECTED APPROACH OF THE GERMANS DEMANDING THEIR PACKAGE. iT TOOK THEM THREE WEEKS TO SOLVE THE WIRING SETUP AND, BINGO, THEY COULD DECIPHER MANNY OF THE MESSAGES. THIS WORK ALLOWED THE POLES TO LEARN THE GERMAN TERMINOLOGY WHICH IDENTIFIED GERMAN UNITS, TANK TYPES, FUEL NEEDS, TROOP LOCATIONS, TO INCLUDE THEIR NEEDS, SUCH AS FOOD, CLOTHING AMMUNITION, COMMANDER RANK AND THEIR CODE IDENTIFIERS AND SO MUCH MORE LEAVING THE BRITS THE SIMPLE DUTY TO KEEP IT CURRENT WHEN CHANGED, THAT WITH ALL THIS INFORMATION TO START WITH. ALL THE GERMAN ARMY COULD BE MONITORED DAILY.

[@ZER0--]

The very best codes to encrypt are from languages you don't know. There were a number of American tribes whose codes were never broken (although it's ironic ,as it was the Europeans that wiped out most of the North American Indians).

[@Geographus666]

+Paul L That is "Security by Obscurity", which is something you do not want in cryptology. The strength of such an "unknown language code" relies solely on the enemy having no knowledge of the algorithm, in this case the language. At the moment they get a person speaking this language (e.g. by someone defecting or being kidnapped and being forced) the algorythm is known and your whole system is broken. Good codes rely on the secrecy of the key not the algorythm, so even if your algorithm is known, your system is secure as long as the keys are. This is called Kerckhoff's principle and is the basis of any modern cypher like e.g. AES.

[@ZER0--]

Geographus666 OK show off. (Only joking.) I still don't understand the public key system, but I understand that it is a very good system PGP relies on that system as far as I know(?). One of the only other things I know about encryption is that prime numbers are used for most bank transactions. If someone can crack primes then the banking system would be up a paddle without a creek.

[@TheArdvaark]

There are certain British codebreakers who wrote some very spurious claims after the war finished. The fact is that Dilly Knox was close to breaking the Military Enigma when we got certain info from the Poles and that enabled Knox to break the Military version in Jan 1940. Had it not been for that info it would probably have taken Knox another 6-12 months to break it - not 2 years. As for 1 messsage in 7, also not true. I know, I work at Bletchley Park and have access to the archive info there.

[@frederickbowdler8169]

Also Polish were sent German enigma by post mistake as two towns one in Poland and Germany have same name . A lot of myths and cover ups with security services that is their stock in trade .

[@sethlester1659]

6 cables = 12 connections = 26*25*24...*17*16*15 = 4,626,053,752,320,000 this means that there would be 487,845,124,504,657,920,000 keys. How did he get only 100,391,791,500 cable combinations?

[@AgentMidnight]

Seth Lester The official formula for unique combinations is (26!/14!/6!/(2^6)), the issue is that you are still double counting a lot of essentially equivalent keys on the switchboard, you have to divide out all the repeats. the 6! is simply all the unique orderings of the 6 plugs that lead to the same equivalent switchboards and the 2^6 means that each of the 6 plugs can be in either direction. Hope it helps!

[@sethlester1659]

Thank you, I knew there had to be some sort of oversight.

[@torch2k]

Good lecture, but his 'word whisker' - 'Okay ...' - was driving me nuts by the end, in no small part because I used to do the same during lessons.

[@craigduncan4826]

How though did the Germans send out the daily key to all the operators of enigmas? Like to tell them, today use plugs in position x y z and have rotors in a b c - send that over encrypted enigma from the night before? Cause if so, you just need to break the enigma once on one day and then forever you can read all their messages, since you will have the rotor/lead settings every day just the same as the German high command. Iv never heard anyone explain how they actually exchanged the encryption keys in the first place

[@IceMaverick13]

Apologies in advance for responding to such an old question: So he mentioned it briefly in his lecture, but the settings were part of a sheet that was distributed with their codebooks. They would distribute these sheets out to the various relay stations and the primary points where Enigma operators were working. The sheets typically had a full month's worth of settings in them, so you'd open up your codebook and it would say that on the 2nd Sunday of the month, here's how to do the initial setup for your Enigma. So Enigma operators would simply plug through the settings as instructed, alongside adding their own personal encryption scheme with a "random" keyphrase. Now every operator didn't necessarily get their own sheet. A lot of times it would be like the head of a relay station would get a codebook and that month's sheet, and they'd go out into their operating room and tell the 10 messengers on staff that day what the settings were and go like that, for the sake of minimizing how many of these things were available. Additionally, the Germans changed codebooks several times throughout the war, like anytime Admiral Donitz thought that one of his subs were compromised and the book wasn't properly disposed of. And then again they changed them when Donitz insisted on going to a 8-choose-3 rotor layout for the Navy, instead of the standard 5-choose-3 that the Army and Airforce used. And then even more times when Donitz adopted the 4-rotor Enigma for the Navy over the standard 3-rotor. So now the actual code abbreviations, phrases, and other keywords were being changed in addition to the sheets themselves being changed. Every time a big change happened to the Enigma system, it just deleted all of the Allies previous work because old samples of decrypted messages and previous setup instructions were made obsolete by the new machine. Capturing a setting sheet did let the Allies read messages for a month and they did that several times throughout the war. They had captured Enigmas and several times got their hands on settings sheets that let them read radio messages. That was great in the short term, but they were trying to solve the long-term problem of not *needing* to capture settings sheets every single month to be able to read the messages.

[@JasonFahy]

Looks like I'm dense. Why isn't the number of possible plug combinations 26C2 x 24C2 x 22C2 x 20C2 x 18C2 x 16C2 = 7.23x10^13?

[@lobsterfork]

I am guessing you made a miscalculation when you glossed over the plug board. The plug-in board is basically 26! which is an absolutely massive number if it was all 26 letters, but it is only 10 pairs, so we can divide those out. Also, it does not matter what order the pairs are in, and it does matter what order the actual individual pairs are in. 26! is then divided by 6!10! and 2^10 So at the end of the day it is: 3 out of 5 possible routers: 60 possible combinations 26^3 for the number of options on each router (total of 3): 17576 possible combinations and the plugin board amounts to: 403291460000000000000000000 DIVIDED BY 2675441664000 So the final calculation is 150738274516158 (plug in board) X 60 (rotator configurations) X 17576(combinations of those rotators) = 158,962,554,773,760,150,279 possible ways to interpret enigma If you did one of these combinations every second through reduction, it would take you about 5 trillion years to break the code. Of course, You will never see a word that starts with xdrft, so that number can be reduced, but even then, it would still take millions if not billions of years.

[@dave28lax]

You've factored in that it doesn't matter which way round the cables are, but you forgot to factor in that the order of the plug cables is irrelevant, so A-B,C-D gets the same result as C-D,A-B. So you need to divide your result by the possible cable permutations, which is 6!

[@JasonFahy]

Aaaah, okay. Thank you!

[@beattoedtli1040]

The number 100'391'791'500 is 26! / (14! * 2^6 * 6!). Then of course 100'391'791'500 * 17576 * 6 = 10'586'916'764'424'000

[@beattoedtli1040]

dave28lax​ I did not intend any offense by my comment, nor to diminish your previous comment. If I had understood in time that nC2 denotes n *(n-1)/2, I would not have posted anything. (But why such a tone? Did I offend you? Let me post, maybe someone else finds it helpful?)

[@hansflaman7428]

Briljant, hold up mike for an hour!

[@bf3knifer]

i dont see why the plug board creates so much extra complexity, whether you swap letters one time or 10 times, the end result is still just one swap, just a different letter and it will be that same letter for the full duration of the day

[@ASMReading_]

If I understood right, it's because the plugboard isn't really there to create complexity for the ciphertext, it's there to significantly expand the number of potential daily keys. So while it's probably not mixing up the encrypted text all that much, the important number to look at isn't that just 6 sets of letters are swapped, but that there are over 100 billion ways to place the 6 cables in the 26 holes in the plugboard. That makes it so there's 100 billion times more ways now to arrange the board every day, i.e. 100 billion times more potential daily keys. Without the plugboard, there are just ~100,000 possible daily configurations/keys, and that's a small enough number to brute force by trying all possible configurations each day. With the plugboard, there's suddenly >10 quadrillion possible configurations/keys each day, which is no longer brute-forceable. So it's about expanding the key space and blocking brute force attacks, not obfuscating the text too much -- the rotors already take care of enough obfuscation. I think!

[@brown3394]

The solution is wrong the answer would have to be be "can attain UP remaining on the level" since the Y was already used, the only other 2 letter word left that can make sense is UP.

[@dylanwhostones]

The germans cracked the allied codes through the war as well- and the allies never knew that either, however the US changed the system in 1943 locking the Germans out after that. They knew the merchant code and thus were able to track allied convoy routes.

[@jimwilson946]

That simply isn't true. The Americans had no crypt analysis as it was disbanded at the end of the First World War and relied on the British to get them back up to speed. German agents in America reported the departure of convoys to their controllers, no need for code breaking!

[@ZER0--]

58:30 I think that the saddest thing is that people had to be sacrificed because otherwise the Germans would have known we cracked their codes. But imagine we did let them know we cracked their codes (!?) What would they do then as a code ?

[@hazelmira2224]

8 źZzz0 566uwu7ùew5aybs3 .

[@ZER0--]

Hazel Mira ?

[@taotoo2]

Paul L LOL

[@Dragonblaster1]

The Geheimschreiber ("Fish"). But that was cracked as well.

[@scottfuller5194]

ZER0 The British, continuing the original enigma work by the Polish cypher mathematicians, "broke into" the revised Enigma MACHINE.....knowing then how it functioned, they worked on reducing the astronomical number of possible permutations, based on mathematical analysis, human technical transmission errors by German enigma operators (repeating encrypted texts in plain language etc), various captured German code books (short weather code, short code, officers code etc, etc) the Atlantic UBoat grid location tables, wiring enigmas in series (this first British "bombe" replicating what the Poles did and showed the British how to do) secretly "acquiring" the enigma technical details held/registered in the British Patent Office, using captured enigma rotors (full set) and captured enigmas, using captured Luftwaffe enigma code books, "acquiring" trashed enigma messages from two German army offices, sending Bombers on specially targetted missions and using the German air defense enigma messages to match up by name, those targets, employing a very large series of "Y" radio intercept stations, "grid-locking" UBoats as part of the British/Canadian and US Direction-finding (HF-DF) "triangular fixing" radio system, using broken Japanese diplomatic codes (the Japanese Military attache in Berlin used to make very frequent, highly technical and very reliable intelligence reports back to Tokyo).....capture of short weather code books from "pinches" made from captured German trawlers, weather ships, UBoat resupply ships etc).....planting disinformation "lost" messages/where they would be easily "discovered and recovered" by German military and intelligence agencies, using British controlled double agents to spoon-feed the Germans a "barium meal" of partly true, mostly false intelligence reports, conducting clandestine commando raids used as tactical cover for special intelligence units "pinches" of enigma (and Lorenz) cypher materials, codes and related documents. There were many other cypher acquisition tactics used.....as now previously ULTRA Top Secret highly classified files are now being declassified and released into public archives......a most recent book: "The Third Reich Is Listening-German code breaking 1939-45" by author Christian Jennings, published and released in October 2018, now reveals the German code breaking successes/failures......!

[@diegorodrigues8287]

He is good in solve problems

[@deeremeyer1749]

I was under the impression that when you use 3-letter "encryption codes" each 3-letter code is permanently assigned to a work commonly used in whatever "industry" or "military service" and in the interests of brevity, simplicity and "speed" the "vocabulary" is kept very small and the actual ENCRYPTION is done so that day to day OR message to message the machines at BOTH ENDS are reset to a new "circuit" and UNUSED 3-digit "codes" are used and are entered as the "code" and the "clear text" at the other end is STILL just a 3-digit "code sequence" that any outside party trying to "decrypt" the messages has to have the DICTIONARY FOR or "cracking the code" doesn't mean jack shit. Any comments on Enigma machines being widely used commercially produced machines found all over the world long before WWII? How does "Enigma" relate to TELEPHONES? Or TELETYPES? Any comments on the similarity of a 3-letter "code message" used by a military force to 3-letter STOCK SYMBOLS used for "international business" going back to the invention of the STOCK TICKER?

[@sun11motty87]

So how did the enigma do numbers?

[@highwaysbyways4281]

They used the top row of the keyboard as numbers, and indicated that they were going to send a number by typing Y. So, for example, if they wanted to type the number 54, they would type YTR.

[@penklislawnmowing4508]

It come down to the author who wrote the book on a 100 ways a cat can catch a rat and 100 ways a rat can escape a rat

[@drdeak]

If he only knew that clip mic has a alligator clip on it...............that's why they call it a bloody clip mic!

[@davidelliott5843]

The British invented the electronic digital computer specifically to crack the Enigma. After WW2, they moved them out of Bletchley Park but kept them totally secret. No commercial use was considered. (1) because the military dong think like that. (2) because the Soviets used Enigma and Britain continued to crack their codes.

[@KANASR66]

they talk about how genius are the code breaker and Alan Turing,,,, and build a huge machine to decrypt the enigma code

[@vanyastaleva415]

I think both are great! If you know a movie about Arthur Scherbius, please share the link here

[@Dragonblaster1]

It is true that many of the perceived faults in the Enigma were in its implementation rather than innate to the machine. However, it takes more brains to crack a difficult cypher than it does to create one.

[@gamesmusichax8359]

"Work for NSA". "$20 is expensive". You poor man... Joking aside, people at the NSA should be making more money anyway, for what they do.

[@unvergebeneid]

Right, all that industrial espionage is probably making the US hundreds of billions so they deserve being paid well.

[@MothaLuva]

GamesMusicHax They should be put against a wall for what they do.

[@Dragonblaster1]

Di Pudriano You have no idea what they do, so enough of the fake outrage.

[@dylanwhostones]

Commercial version was easy from what I've read. The military machine was more difficult to understand. British code breakers have admitted the whole effort would have been put back two years had it not been for the Poles. War could have been lost by then. In the Med both the British and Italians were only able to decode about one message in 7 in 1941. The rest of the transmittions went unintercepted. Same was true of decoding German & British naval messages at that time .

[@organbuilder272]

What is it that is Okay - This comes up repeatedly. Is this a keyword. A ceasar shift.

[@bhagyalakshmi1053]

What is a Win -vnzuoted :

[@sergeolenek7414]

interesting, very