The History and Mathematics of Codes and Code Breaking

Month: October 2015 (Page 1 of 5)

Computer Ciphers

Two resources from today's class:

  • An ASCII table, showing how to translate characters (like "a" and "@") into numbers that computers can understand.
  • Today's Computer Cipher Worksheet, which features several questions about binary numbers. We went over questions 1 through 4 during class today. See if you can make sense of question 5 before class on Monday.

Little Brother Links

A few Little Brother links for you, most of them mentioned in class...

  • Cory Doctorow blogged about my blog post about our in-class debate map activity.
  • On Twitter, I asked Cory Doctor about the terms "surveillance" and "security" as they apply to this debate. Here's what he said.
  • Here's that streamgraph showing the use of words in Little Brother from start to finish.
  • Cory Doctorow wrote a sequel to Little Brother called Homeland that describes the continuing adventures of Marcus Yallow.

Paper #2 - Lessons Learned

Here's the info on your second paper assignment: Paper #2 Assignment (Fall 2015). I'll share a rubric for this assignment just as soon as I draft one. Note that a draft is due Wednesday, October 28th. Final papers are due Monday, November 2nd.

Update: I now have a draft rubric available for this assignment. Paper #2 Rubric (DRAFT)

Little Brother Debate Map (2015)

I snapped a photo of the debate map we constructed during class on Monday. We'll talk more about Little Brother in class tomorrow, and I thought you'd want a copy of the debate map for reference. Recall that orange Post-it notes captured pro-security arguments made by characters in the novel, while magenta Post-it notes captured pro-privacy arguments. Click on the image for a better look. And if you're really interested, check out the 2012 debate map and the 2014 debate map.

Little Brother Debate Map 2015

Timeline Assignment

Instead of a bookmark assignment this week, I would like you to continue enhancing the cryptography timeline we explored in class last week. You have two tasks:

First, select two existing contributions to the timeline and improve them. Verify the description, as best you can. Include a credible source with citation and, where available, a link. Make sure there's an associated image or other type of media with citation. And add your initials as contributor.

Second, add two new contributions. See your textbook, our Diigo group, or the Wonders & Marvels essays by past students for ideas. Be sure to cite a credible source, add an image or other type of media, and include your initials.

Here's the Google spreadsheet that powers our timeline, and here are some instructions for using TimelineJS: general formatting instructions, embedded media options.

Your timeline contributions are due by the start of class on Wednesday, October 21st. Please note: Any work you did in class last week counts toward this assignment, and if you worked with a partner during class, you can both count your contributions. This means that most of you are already half done!



When privacy becomes a privilege

Since Marcus was questioned by the National Homeland Security after “being at the wrong place at the wrong time”, his freedom has been taken away from him. During the journey, he has fought himself all the way to the end of the story for his rights,  freedom and privacy. In this specific setting, these rights, freedom and privacy are no longer what we “suppose to have”, but rather a privilege that need to be earned.

Coming from a country where websites or tools such as Google, Facebook, Gmail, and Twitter are all blocked, I witnessed people’s different attitudes and approaches to this seemingly harsh censorship. Some would, as Doctorow suggests, getting around the Great Firewall of China by using an encrypted connection to computer in some other country (p. 112); some would physically get through this firewall, which is what I ended up doing. Either way, people would take some risks or make some sacrifice for the privilege to own their privacy. On the other hand, others, probably happen to be the majority of the population, either don’t really care about this censorship or choose to do nothing with it.

That really got me thinking, why would we care about privacy anymore while a lot of people around us seem to think it’s no big deal? And again I asked the question I asked when I wrote the first paper: why would we care about data mining if we are doing nothing wrong? Doctorow offers his answer to the questions in “Little Brother”– because privacy does matter. It is not about doing something wrong or shameful, but about doing something private, about having some corner of our lives that is ours, and knowing no one else gets to see it. (p. 57)

The False Feeling of Security

I greatly enjoyed the class debate passages (p. 92-93, 175-182) in Little Brother. In the first debate, Marcus brings up the effects of terrorism and the problems with reactions to it.

Marcus' argument about the effects of terrorism involves the types of reactions societies have to acts of terrorism. Post-attack, his school system decides to install cameras in every classroom and hallway. He argues that this reaction gives into the terrorists' goals, because it fosters fear in the students and does nothing to truly protect them. In general, I agree with Marcus. The cameras give a false sense of security, pretending to be preventative measures when in truth they can do nothing to defend the students in the event of an attack, or to prevent one from happening. All the cameras do is watch and wait, ready to catch evidence to incriminate terrorists, which will be of no comfort to the victims of the attack. Therefore, the cameras are not much more than constant reminders of the events of the past and of all the fear there is to be felt in this world.

This concept reminds me of the heightened security after terrorist attacks, like 9/11. Post-9/11, airport security was entirely remade, and incredibly tight procedures were created. However, while some of these procedures can prevent and protect, they have their issues. The new procedures in any post-attack scenario increase security on the target of the attack--in this case, planes. The problem is, airports and planes are just one potential target, and it's unlikely that, having used that method, a terrorist group will choose to use it again. This isn't to say that increased security and tightened protocols are poor uses of resources. They are, of course, necessary and good. However, they do not automatically mean that everyone is safe. In fact, it seems to me that even as new security measures are important, they also allow the terrorists to accomplish their goal. Without the precautions, we leave ourselves open to other attacks via the same battle-tested methods. However, with the precautions, we focus our attention on one group of targets, associate fear with said targets for some period of time, and use valuable (but necessary) resources to defend them, without any real knowledge of the next potential target. These are the problems of being on the defensive, but they are issues to which I believe cryptography can hold the answers.

Why Do We Want Privacy?

"It's not about doing something shameful. It's about doing something private. It's about your life belonging to you" (Doctorow 57).

The idea in Little Brother that made me think the most was the idea of personal privacy and why that is so important. On page 57, Marcus compares a betrayal of personal privacy to a situation where you had to use the bathroom in a glass box in the middle of New York City every time you had to go. Everyone uses the bathroom, but it is a private and personal part of our lives, not something we want to share with everyone. So while Marcus didn't have anything really illegal, and definitely not at all related to the terrorist attack, on his phone, he didn't want to give "severe haircut lady" his password because his phone had private information that was his personal space. Throughout the novel, Doctorow explores the balance of protecting privacy and stopping terrorism. Homeland Security's efforts to find terrorists causes divorces and fights, things brought to light when their privacy was compromised. Xnet begins in the first place so kids can play video games and email away from the snooping DHS. This widespread desire for a private corner of our lives is why cryptography is so prevalent in our lives. As Vanderbilt students, our emails, web browsing, and phone calls are likely (and hopefully) nothing illegal: emailing professors about homework, calling home to parents, and ordering a pizza. But that doesn't mean that we want everyone to be able to see that. Cryptography allows everyone a sense of privacy and a way to create that privacy. However in this novel, Doctorow asks an important question: how much of this personal privacy are we willing to give up in the face of terrorism? Whether you agree more with Marcus or his dad, I think everyone would agree that the government in Little Brother gave far too little respect to personal privacy.

Inaccurate Accuracy

Though there were a lot of interesting insights made throughout the novel regarding cryptographic security, the point that most stood out to me had to do with the "paradox of the false positive."  In chapter eight of the novel, Marcus comes up with the idea to clone arphids in order to create a high number of unusual travel patterns and consequently bog down the DHS's tracking systems. He goes on to describe how anytime you are trying to collect data on a wide scale, lets say for example from one million people, the test's percentage of accuracy needs to be the same as the uncommonness of the thing being looked for. For example with one million people being tested, a 99% accurate test would still find 1,000 positives, which would be very unhelpful if you're looking for only one specific person. The more people, and the less common the variable you're searching for, the more unusable your test becomes.

What I thought was so interesting about this point is that when looking at the math for this sort of data mining, it seems so illogical. The probability of finding usable data in this manner becomes more and more difficult as the amount of data increases. However, just hearing the phrase "99% accuracy" creates an inherent false sense of security. This false sense of security becomes dangerous when we rely heavily on technologies such as these to find information for us. What happens when the accuracy is lower than 90%? Lower than 80%?

One thing we have discussed in class more than once is the idea of data mining, especially in schools, to attempt to find patterns that would predict crime before it occurred. The point that always gets brought up in favor of this sort of data mining is that it potentially could keep students safe, which of course would be beneficial. However, lets say that these measures were implemented at Vanderbilt, with 12,725 students, and the test had a reasonable 95% accuracy rate of finding potential threats. Theoretically 636 students could be found potential threats by the system. It's improbable and illogical to question over 600 kids in order to find a possible one or two actual suspects. Though neither Marcus nor I were making the claim that all data mining is useless, seeing the numbers on how useful it really is puts the idea into a better perspective.

Cryptography by the People for the People

The passage that stuck out to me the most from the novel was Marcus’ description of the use and benefits of cryptography from page 57. Even though it’s at the beginning of the book, this passage gets to the core of how cryptography works for us today. Cryptography is used by everyone because is as accessible to everyone. Thankfully, our government does not have a monopoly on cryptography; “the math behind crypto is good and solid, and you and me get access to the same crypto that banks and the National Security Agency use” (Westerfeld 57). Because it is so widely used, we can be sure of its effectiveness.
The quote continues to discuss how cryptography is useful to us today. Even if we do not have anything to hide, “there’s something really liberating about having some corner of your life that’s yours, that no one gets to see except you.” This reminds me of the article I read regarding the actions of the National Security Agency and invasion of civilian privacy due to bulk data collection. The fact that personal information as well as government intelligence is encrypted using the same means shows that the government has access to all of our information as well. This is not a bad thing; access to this information can be useful in ensuring peace. The question still remains: when does government access of individual data cross the line from protection to trespassing?

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