The History and Mathematics of Codes and Code Breaking

Tag: Mary Queen of Scots

Watch Out for the Middleman

The section of the book that most caught my attention can be found at the beginning of Chapter 10. Marcus is in the early stages of setting up the Xnet and is beginning to realize that his heavily encrypted system is most likely already infiltrated by members of Homeland Security. He asks himself what the right course of action would be and makes clear his intentions of feeding the false information to both sides in what he calls a "man-in-the-middle attack". The process of steaming open letters is described and Marcus uses the metaphor of being a fat spider in the middle of communication to cause as much havoc as possible.

I find the idea of "man-in-the-middle attack" very interesting and it is something we have discussed a few times in our cryptography course. A prime example of this attack can be found in Singh chapter one when Mary Queen of Scots is imprisoned but still sends out instructions to attack Queen Elizabeth with weak encoding methods. Cryptanalysts were able to intercept Mary Queen of Scots's letters, thus allowing her to be incriminated and manipulated by Queen Elizabeth's men. Marcus's solution to the problem of a "man-in-the-middle attack" is crypto of course. He describes a confusing method of encryption involving a double key which creates a double enciphering. I, however, was more interested in Marcus's form of attack rather than his double key form of defense.

Environments that promote or discourage confidence in codes

Before the development of the Vigenère cipher, those sending encrypted messages understood that if the message was found, any good codebreaker would be able to decipher it. Mary Queen of Scots experienced a very different environment. She had total faith in her cipher and never guessed that anyone would be able to decipher her messages if they were intercepted. Because of this, Mary Queen of Scots did not bother to write discretely about her plans with her aides.
Before the Vigenère cipher was developed, those that wrote and sent encrypted knew the risk of interception did not speak so plainly about the topic of the message as someone that had confidence in their encryption would. This kind of environment that fostered insecurity was complete with numerous Black Chambers. Black Chambers were centers where messages intercepted through the mail system were then analyzed and attempted to be deciphered. Through this, valuable messages that had been deciphered could be then given or sold to various European powers as crucial intelligence.
Due to these kinds of operations, there was no way for people to be totally confident in their ciphers, something that got Mary Queen of Scots executed. The development of Vigenère cipher allowed for a greater confidence in the security of people's messages.

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Be vague and Roman Numerals

After the execution of Mary Queen of Scots but prior to the development of more complex ciphers, like the Vigenère cipher, "anybody sending an encrypted message had to accept that an expert enemy codebreaker might intercept and decipher their most precious secrets." (Singh, p. 45) Because of this, it is safe to assume people writing the encrypted messages would still be very careful with what they were actually saying, and how the things that they wrote could potentially incriminate them. Messages would have been written in vague enough language that even if the text were to be deciphered, the cryptanalysts would either not be able to tell what the exact plan was or, even if they could figure it out, would not be obvious enough to be used in a court of law. (I don't know how the rules for this worked in that time but today people can claim the way a message is interpreted is completely wrong.)

Going off in a completely different direction now, as I was reading I was thinking of different types of ciphers. When I the name Louis XIV, I fixated on the Roman Numerals. It made me curious about the use of Roman Numerals in cipher alphabets. I think it would add a layer of complexity because the cryptanalysts would have to try to figure out which combinations of letters would represent a number, and then which letter was represented by that number. One weakness, however, would be that it would be very easily identifiable as Roman Numerals because of the small number of letters used in Roman Numerals. I tried to look up Roman Numeral ciphers but nothing came up on a quick Google search.

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Securing Codes

As I read the first chapter of The Code Book by Simon Singh, I found that the ways to protect yourself while making encryptions is what resonated with me most deeply. Obviously, Mary Queen of Scots was not able to cover her tracks and was executed for her participation in a conspiracy that would try to kill Queen Elizabeth. Before taking Cryptography, I had always assumed that encryptions and codes were secure regardless of the strength of the enemy. Now I realize that one had better make sure that they either have a strong communication system or a strong encoding system. However, there are many more things that a code maker can do to protect themselves.
In my opinion, the largest mistake Mary Queen of Scots made was not changing her codes between her and her conspirators. Although changing the key of their encryptions would be a more thorough cover, changing the cipher can be done often and will deter the efforts of any hackers. Simply by putting a number in the text of an encoded message, the receiver would know to shift the numbers in the text to change the message. There are simpler ways to enhance an encryption as well. This could involve intentionally misspelling words to make the message more difficult to decode, but remain legible for the recipient. These changes enhance an encryption and help to protect the sender. There are many more truths I hope to discover in Cryptography.

Blog Post #1

I can honestly say that going into this class I had very little knowledge of what cryptology is or its implications. I had most likely heard the word in passing but never fully tried to comprehend the true meaning. The first chapter of Singh was to say the least an eye opener. I was shocked by the widespread use and history of codes and ciphers. The chapter expanded on the history of ciphers in various societies and cultures. The main example of the first chapter is Mary Queen of Scots and her cipher mishap. This situation displays the risks of ciphers. As discussed in class, sometimes a weak cipher can be worse than no cipher at all. The reasoning behind this is the false sense of security that a cipher can give the sender and recipient. Mary Queen of Scots also made the mistake of trusting someone else to deliver and keep the secrets safe. As the saying goes, “loose lips sink the ship.” Well in Mary Queen of Scots case deception, ciphers, and double agents sank that ship. The discussion in class led me to realize that Mary had no other option than to trust that her correspondences were honest since she had very limited resources. This ties into another topic that we discussed about the impact that resources has in ciphers. In Mary’s case, the limited option of resources and possible ways of communication forced her to relay on her a double agent. She had no way to change the cipher or strengthen it without him knowing so she was sort of doomed. If she was more vague and a little less trusting in the strength of the cipher she could have saved herself but that did not happen. The discussion in class aided me in seeing the scope of ciphers along with the potential drawbacks of them.

Blog Post #1

What surprised me most in the first chapter of this text was just how old cryptography is. I guess I had never really thought about it's origins before the reading. I thought it was really interesting to learn of the origins and to begin learning some history. It made me draw come comparisons to cryptography today. Cryptography really has come a long way since Queen Mary used it from her jail cell. Although it's incredibly unlikely that a ruling leader would ever be held in jail by another, if the situation would arise, and they needed to use cryptography, it would happen quite differently. First of all, I think they would have a better understanding of the likelihood of the messages being intercepted and broken, and would not use such plain terms to describe their plan. Mary and Babington's foolishness reminded me of in middle school, a group of girls would speak in pig latin, thinking nobody else could understand them. Unfortunately for them, many people also knew of this "secret" language, and those who didn't quickly caught on. Another advancement is simply the difficulty of the cipher that would be used today. In this day and age, a simple substitution cipher, like the one used by Mary and Babington, would be deciphered in minutes. To really keep something private, a much more advanced and complicated cipher would be needed.

Better Safe than Sorry

In the “Tube” chapter, Captain Waterhouse visits Detachment 2702 and discusses with Colonel Chattan the possible height problem of the women working the bombes. All of the women that work with the bombes need to be tall enough to wire up the tall machines, and Waterhouse and Chattan entertain the idea that the Germans can obtain the personnel record of Detachment 2702. The personnel record would reveal that there are an abnormally large number of tall women working at 2702. Waterhouse and Chattan then assume that the Germans have an open channel to retrieve the records and discuss possible solutions.

The dilemma that Waterhouse and Chattan face resembles a situation in which two parties are exchanging messages but do not know that a third party is reading the messages. As seen with Mary Queen of Scots, assuming that one’s cryptosystem is secure can lead to carelessness and result in severe consequences. The conclusion reached in class discussion is to act like there is a third party that can decrypt one’s messages and to take extra measures to conceal the meaning of the message through euphemisms or symbols. The military officers in this scene assume the position that their enemy is able to access their data freely.

Their solution to this problem is quite innovative. Instead of outright closing the channel and blocking their enemy’s access, they keep the channel open so the Germans won’t suspect anything. They also decide to feed false information through the channel to fix the height anomalies in their personnel records. Their strategy effectively turns their disadvantage into an advantage. Using an enemy’s advantage (breaking the cipher) to manipulate them (feeding them false information) is an ingenious strategy. But this strategy requires the knowledge that the original cipher is broken and that a third party can read the message. Employing this strategy requires an essential assumption discussed earlier in the course: no message is completely secure, and to be safe (and paranoid), one should act like the cipher is broken.

Image: "Bombe detail," by Garrett Coakley, Flickr (CC)

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