Cryptography

The History and Mathematics of Codes and Code Breaking

Tag: decipher

Great Mind Games, Britain

As discussed in the book, initially, the British were quiet and low-key when it came to the fact that they could decode Germany’s messages during the first world war. But then, Winston Churchill and the British Royal Navy decided to let it be known that they knew how to break the codes all along. Upon learning that their codes could be broken, the Germans began to invest their smarts into the Enigma machine technology. So should the British just have stayed quiet about their decoding abilities? Personally, I say no.

By letting Germany know that they could decode their messages after the fact, I believe it could have made the British feel as if they established some type of superiority over Germany. Such as a taller person dangling an item over the head of a shorter person, knowing that the shorter individual cannot reach it. It’s like a “Na-na-na-boo-boo,” moment for the British. They were so proud of their achievement, of course they were not going to stay quiet about it for too long.

And even then, it is not as simple as to say that they were just proud. They knew that it would give Germany this kind of doomed feeling even though everything was revealed after the fact. Germany must have been so secure with themselves, so secure with their encrypting strategy only for them to find out that their messages could be decoding the entire time. It is like a punch in the gut, believing something of yours was great all along only to be proven that it is not really all that good. Maybe I am reading too deep into this, but I believe there could have been some type of psychological aspect to this, and if this was done just to play mind games with Germany, it was smart.

But then it led to the creating of the Enigma machine, which was maybe not particularly great, but great mind tricks, Britain.

Solving an Encryption is Easier Said than Done

I believe that the examples in the book would be harder to decipher when no assistance is given. It would be hard to decipher the message while not knowing what type of cipher it is. Telling the readers what kind of code the message is encrypted as gives a hint in how to solve it. If there was no hint, the receiver of the message would have to just guess on how to decipher the message. There are ways to get clues on what type of code is used such as frequency analysis; however, frequency analysis may not be very helpful depending on what type of code was used.

It is easy to understand Singh’s examples in the book because he is trying to teach the readers how to decode the message. The examples that Singh gives are also easy to crack since no one is trying to keep the message hidden anymore. It is easier to decode the messages now than it would be during the time of war. I think that it is harder to decipher codes when in certain situations. The idea that the contents of a message can help alleviate impending war can put an enormous amount of pressure on a person’s shoulder. When I am in stressful situations, an exam, for example, I often make silly mistakes because of how nervous I am. That feeling is a thousand times worse during the times of war because it is not a grade that is at stake, it is the livelihood of a country.

 

How was the German cipher deciphered in World War II?

At the Brechley Manor, in addition to Knox, the deciphering community, there is also a mathematics wizard, Turing. He graduated from Cambridge University and relied on his research on cryptography after the war. He became one of the pioneers in the era of electronic computing.

First of all, they started with the development of a machine that can imitate or explain every “dummy mystery” of the German Defence Force, so that it can launch all the coding procedures that are frequently changed when the main command of the German army is issued day and night, and when the adult orders are issued. After a difficult attack, the British finally made the machine with the above functions and named it “bomb.”

At the end of 1939, the “bomb” deciphered the German code, and the British were ecstatic. Since then, the German secret plan and action plan has been continuously transmitted from the Brenchley Manor to Colonel Menzies, and then directly to Churchill’s desk. In fact, most of the German actions during the “World War II” failed to win the British, but the British have always concealed the source of intelligence, and have never caused doubts from opponents.

On July 2, 1940, Hitler released the first “Sea Lion” combat plan, which is also the British local landing operations plan. At the beginning of the campaign, Churchill and the Air Force staff learned most of the German Air Force – sometimes even all of them – through “super secrets”.

In response to the command of the German Air Force Commander Goring to seize the air superiority, the Royal Air Force has developed a plan to concentrate its superiority against the enemy. Since the number of aircraft of the British Air Force is not much in Germany, the fighter squadron and the main defensive forces can only be concentrated at the appropriate time, in the right place and at the appropriate height to deal with the enemy’s main attack power. Relying on early warning radars and deciphered German military intelligence, the Royal Air Force can always take advantage of the arrival of the Nazi Air Force to accurately intercept the interception, without the need for time and space patrols to guard against German raids – the British Air Force has greatly reduced the pilot’s physical consumption and gasoline Wait for strategic material consumption.

On August 13, 1940, over Sussex and Kent, 80 German “Donil 17” bombers, and a larger number of “Junker 88” dive bombers, flew to the British hinterland and coastline to carry out bombing missions. Due to the dense clouds in the sky, the German escort fighters could not take off as planned, and the bombers had to attack alone.

The British Air Force Command had already known the German action plan in advance. When the German plane was found on the radar, it immediately launched an operational plan that was already ready. In this confrontation, the German Air Force lost a total of 47 aircraft and more than 80 were injured. The British Air Force lost only 13 aircraft.

So actually in the WW1, the cipher of the German military should not be posted. It directly results in that the cipher of WW2 is deciphered.

Ethical? Necessary.

In the movie “The Imitation Game,” there is a scene that Alan Turing and his team deciphered a message indicating that there is going to be an attack on the British Navy. After celebrating for finally able to beat the Enigma Machine made by Germany, they calmed down quickly and decided not to present the message to the British Navy. It’s confusing for me at first of why they chose to keep the attack as a secret, but I then understood the importance of keeping some of the messages private for the good of the big picture. It took unimaginable great effort for Turing’s team to figure out how to defeat the Enigma Machine. They can’t risk the chance to let the German Intelligence find out that they cracked the code. If they changed the Enigma Machine into other types of encrypting methods, more damage than a team of warships would be made and the war might have gone in another direction. In special times, some small sacrifices need to be made to win the war.

      It’s just like what Admiral Hall did to President Wilson. If they can’t find a source of retrieving the information that they can explain, the Germans will change the encrypting methods, and the British cryptanalysts will lose the advantage. Is it ethical? It’s probably not. However, it’s the war situation; so it needs to be treated differently. Admiral Hall did this so that the American, the most powerful country in the world, can join the Allies and fight German. It’s the war strategy and leads to an acceptable result. When the messages were spread out later, the damage made can be accepted for the privilege of the great world war.

On the other hand, after the Americans joined the Allies, it’s also helping the Americans if they have access to decipher the German messages. Therefore, it’s necessary for Admiral Hall to keep some messages secret. It’s too much to risk as they will lose all of their achievements the fact that they broke the German Code was known.

The Greatness of the Great Cipher

I see The Great Cipher is synonymous to the simple monoalphabetic substitution cipher, just on steroids. The concept is the same—one cipher letter or multiple cipher numbers represent a number of plaintext letters. However, what makes the two so different in their difficulty to be cracked lies in the sheer possibility of combinations that could be created from each cipher.

The cipher key was not limited to just one letter replacing another; instead, a few numbers represented syllables. Thus, this opened up a lot more possibilities to stump cryptanalysts.

Before, it was clear in monoalphabetic substitutions that one cipher letter represented one letter of the plaintext. Therefore, we were only faced with a certain amount of different cipher keys to deal with. Even though a completely random monoalphabetic cipher would yield so many possibilities, frequency analysis could easily help decipher it. But now with a cipher with undeterminable characteristics (does “1” represent a letter or does “123” represent one letter? Or a syllable? I’m guessing they did not know how many numbers represented how many letters), patterns that lead to the cracking The Great Cipher become less obvious. There is a multitude of syllables that exist in the French language, making combinations all the greater in amount. This increases the difficulty because although we might see a string of numbers or other patterns, the specific plaintext it refers to—whether it be just one letter or two or three—has much more holes and traps. 

In addition, many people might still be familiar with only the mono alphabetic substitution (since cryptology was still developing), so people might have not thought in a “numbers now represents syllables” way just yet. A reason for the people’s unfamiliarity would be that since the Great Cipher was made by two people (the Rossignols) who already knew how to crack extremely hard ciphers, their knowledge of the weakness of strong ciphers bolstered their knowledge to build something knew that didn’t fall into the traps of the simple mono alphabetic substitution cipher. As such, because they thought five steps ahead of everyone else. In addition to their death, the Great Cipher remained unsolved for 200 years because the only people smart enough to crack hard ciphers and used the weakness of those to create a new super hard to crack cipher had died. In short, their knowledge of the Great Cipher died along with them until it was unearthed 200 years later.

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