The Coded Message in Cryptanalysis and Ways of It`S Analysis

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Updated: Mar 27, 2023
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Code Breaking, also known as cryptanalysis, is the study of analyzing information systems in order to study the hidden aspects of the systems.

During World War II, Bletchley Park in Buckinghamshire was Britain’s main decryption establishment. The Government Code and Cypher School were a closely guarded secret for years. The estate housed the intellect which regularly penetrated the secret communications of the Axis Powers (specifically German, Italian, Japanese, and Soviet signals). The teams also developed automatic machinery to help with decryption.

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These included things like Colossus, the world’s first programmable digital electronic computer. According to the official historian of British Intelligence, the “ultra’ intelligence produced at Bletchley shortened the war by two to four years. And ultimately saved thousands of lives. 

In the 1950s, an English mathematician, logician, philosopher, and cryptanalyst named Alan Mathison Turing began to develop his ideas behind code breaking and computing at Bletchley. His ideas would become influential in theoretical computer science and provided formalization of the concepts of algorithms and the Turing machine (essentially a general-purpose computer). During the second world war, he worked with the Government Code and Cypher School (GC&CS) at Bletchley Park.

While studying here, Turing led a number of operations. Early in the war, he and his team easily understood the German’s monoalphabetic cipher. But when the Germans created a new polyalphabetic cipher, the minds at Bletchley were hard at work trying to decrypt the new codes. Much of the time spent at Bletchley during the war would be devoted to understanding the German’s new ‘Enigma Machine.’ Under Turing’s control, the branch played a pivotal role in cracking intercepted coded messages that enabled the Allies to defeat Germany at many crucial points. 

The mathematics behind codebreaking is fairly simple. First, you must determine what type of code you have. There are three main types. The first one, a Caesar Cipher, involves sequences. The person writing the message must choose a key for their code. Instead of writing the letter A, one might write E. This would make the key 4. So to find any letter… A(n)= n+4, where n is the letter’s number in the alphabet (0-25), and 4 is the key value.

The second type is monoalphabetic ciphers. This type is also called frequency analysis. In this type, the code is based on one letter of the alphabet standing in for another letter consistently throughout the message. There is over 400 Septillion (403,291,461,126,605,635,584,000,000 ) ways to encrypt this type of code. In order to crack these codes, you must use the average frequency of letters used in the code’s language. You then find the average frequency of characters in the code and compare. For example, the letter E is used about 13% of the time. So, the letter or symbol used the most will most likely be E.


In the third type, a polyalphabetic cipher, the way the alphabet is scrambled changes throughout the code. This makes frequency analysis useless. But soon, the staff at Bletchley realized that in a long enough message, some patterns of the coded message would still show up. So, by counting how many letters separate those repeating patterns, the cryptographer can decide the length of the key. Once the length of the key is known, frequency analysis is used to discover the message.

The machines studied, used, and developed at Bletchley were some of the most advanced computers ever. After discovering that polyalphabetic ciphers were more effective, the Germans developed the Enigma Machine. In this system, the key would change for each letter typed. After realizing the change in coding, mathematicians at Bletchley quickly began work to build a machine smarter than the Germans. This led them through multiple early-stage computers. For example, the Colossus Computer was developed to help aid in the cryptanalysis of the Lorenz cipher. This computer used thermionic valves to perform Boolean and counting operations.

Then, the scientists began the groundwork for the ENIAC computer. The device was Turing-complete, digital, and able to solve a large class of numerical problems through reprogramming. It was the work of this computer that would enable the mathematicians to build The British Bombe. This device was an electro-mechanical device used by British cryptologists to help decipher German Enigma-machine-encrypted secret messages. The device was designed to discover some of the daily settings of the Germans Enigma machine. It was the success of this machine and the scientists at Bletchley that led to Ally’s ability to break Axis codes. One of the main questions that scientists at Bletchley Park attempted to answer is, Can you create an unbreakable code? Well, at first, the logicians thought the answer was no.

This is because one must follow a set of rules to encrypt the information of a code. Therefore, it was thought that with enough time and data, those rules could be uncovered. But, as staff at Bletchley discovered, one could create this ‘unbreakable’ code. It is created using one-time pad encryption, which uses a key as long as the message itself. This way, there are no encrypted patterns left in the message, leaving nothing to analyze. For this to work, the sender and the recipient have the same pad/key. For each message transmitted, a new pad/key must be used. Unfortunately, this method doesn’t always work. This is because the sender and recipient MUST have a matching pad/key.

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The Coded Message in Cryptanalysis and Ways of It`S Analysis. (2023, Mar 27). Retrieved from