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Lecture #1:  Introduction & Caesar cipher


I tried to show a video tape about cryptography (COMAP's Cracking the Code, about 15 or 20 minutes long, perhaps intended really for a high-school audience). I was unsuccessful: instructional technology is terrible! It later turned out that the machine was broken, although I didn't know this at the time. I finally needed to have it repaired late in the semester to show a videotape about Enigma.

I discussed who the course was aimed at: not math or CS majors, but people who wanted to see current controversies in public policy and whose interest and training in math were not deep yet who might have some slight desire to have the relevance of math shown to them. I said that it was my responsibility to teach them math, and that my success would be measured by how they responded. It was their responsibility to be alert and to come to class -- the material was highly non-standard, and few classes would be straight classical lectures.

Among the public policy issues I mentioned were intellectual property, privacy (e.g., medical and financial records), government policies (U.S. and others) about secret/confidential communication, and the security and success of e-commerce (transactions "on the web").

I discussed my own background a bit (interest in mathematical and practical aspects of crypto, and in the policy questions), and mentioned the interest in crypto of the teaching assistant, Mr. Radomirovic.

I had brought in a cell phone and a laptop computer. I remarked that most cell phone conversations in the U.S. could be readily overheard -- they were almost public. I stated that, paradoxically, I could be arrested for taking the laptop out of the country with certain programs on it, but that if I printed out the programs and took them out of the country, there would be no legal problems! Later in the course I distributed copies of Matt Blaze's essay, "My Life as an International Arms Courier", which discusses some aspects of this situation.

I mentioned the considerable amount of current change occurring in this field, and tried to contrast things I had said in the fall in this course with what I can say now. In particular, I touched on changes in U.S. export regulations, the breaking of the DVD encipherment, and the substantial weakening of European cell phone privacy protection.

I gave out the anonymous questionnaire [PDF|PS|TeX] about math and policy whose results are available. I gave out a student information sheet [PDF|PS|TeX]. I gave out information about the course [PDF|PS|TeX]. I had people break up into small groups and try to decipher a Caesar cipher (with only a very rough discussion of what such a cipher was). I also gave frequency distributions of the letters in the message [PDF|PS|TeX]. I also gave out copies of the relative frequencies of letters in English from Beutelspacher's book (page 10).

The first homework assignment followed my constructing a web page of student names and majors and e-mail addresses. Each name was written in a different color. Each student got an e-mail message from me asking them to examine the web page and report what color their name was. In some cases I was also able to ask questions and give information about the course in answer to what they had written on their information sheets. Thus I was able to check that students could communicate by e-mail and could look at the web.


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