Announcements will appear for awhile on the course home page and then be archived here.

• 16 Nov. I ran my solution to PS5 to generate some sample output. (Hopefully it's correct.) This file can be found on the Zoo in directory /c/cs467/assignments/ps5.

• 14 Nov. I just posted notes for today's lecture 19 (.pdf) (which also include a bit of next Thursday's lecture).

• 13 Nov. I have revised Problem set 5 (.pdf) again to make it easier to program and to avoid some annoying special cases.

  1. p₀ should be an odd prime. This insures that p₀+1 is not prime, so u ≥ 2, p ≥ 7, p-1 is composite, and every prime divisor of p-1 is proper (i.e., less than p-1).
  2. In the Lucas test, it is enough to try all of the prime divisors of p-1. One doesn't have to try all (proper) divisors. The "proof" to be printed out that g is a primitive root should only consider prime divisors q of p-1.

  These corrections appear in revision 3 of the assignment handout.

• 12 Nov. In Problem set 5 (.pdf), p should be chosen as u*p₀ + 1, not u*p₀ - 1. This allows p-1 to be easily factored. The correction appears in revision 2 of the assignment handout. Thanks to Eric for pointing out this error.

• 9 Nov. I posted notes for this week's lecture 17 (.pdf) and lecture 18 (.pdf).

• 9 Nov. Problem set 5 (.pdf) consists of a single programming problem to find primitive roots of large primes that would be suitable for use in various discrete-log based protocols. It is due on Thursday, November 16.

• 6 Nov. Solutions to problem set 4 (.pdf) are available.

• 6 Nov. I posted notes for last week's lecture 15 (.pdf) and lecture 16 (.pdf).

• 27 Oct. I posted notes for last Tuesday's lecture 14 (.pdf). Notes for lecture 13 (.pdf) were posted last week and listed on the lecture notes index page but not announced here. I've gone through all of the lecture notes and changed the links to other lecture notes to point uniformly to the HTML version of the page rather than the PDF version. Someday maybe I'll fix it up so that the links on HTML pages point to other HTML pages, and links on PDF pages point to PDF pages. In the meantime, I try to keep a complete set of links on the lecture notes index page.

• 23 Oct. Solutions to problem set 3 (.pdf) are available.

• 22 Oct. I posted a study guide for midterm examination (.pdf) and solutions to problem set 2 (.pdf).

• 18 Oct. I posted notes for Tuesday's lecture 12 (.pdf).

• 18 Oct. I just posted Problem Set 4 (.pdf). It is due before midnight on Thursday, October 26. I apologize for making it due on the same day as the midterm, but I think you will find it useful as preparation for the midterm, both for the material that it covers and as samples of the kinds of questions I like to ask (in contrast to problems taken from the textbook). None of these problems requires a computer, but a calculator will certainly be useful.

• 18 Oct. The midterm examination will be given in class on Thursday, October 26.

• 13 Oct. I posted notes for Thursday's lecture 11 and also corrected a minor typo in lecture notes 10.

• 12 Oct. I just posted notes for Tuesday's lecture 10.

• 10 Oct. Late-breaking news: We will be meeting in AKW 400 from now on, starting today.

• 10 Oct. Problem Set 3 (.pdf) is available. It is due before midnight on Thursday, October 5.

• 5 Oct. I've released expanded notes for today's lecture 9 and corrected a minor error in lecture notes 8.

• 4 Oct. I've posted notes for lectures 7 and 8, and draft notes for tomorrow's lecture 9. The math symbols don't always look nice in a browser. Remember that PostScript and PDF files are also available. Links to them can always be found in Lecture Notes.

  I've also posted three handouts on number theory that summarize and extend the material in the lecture notes. Links to them can be found in Handouts.

• 28 Sep. Problem Set 2 (.pdf) is available. It is due before midnight on Thursday, October 5.

• 26 Sep. I've posted notes for Lecture 6. They attempt to correct the confused presentation I gave about MAC's in yesterday's lecture. The method I gave for using a MAC with an encryption function to achieve secret authenticated communication has problems. Better is to encrypt the message first and then compute the MAC from the ciphertext rather than compute the MAC directly from the plaintext message.

  Also, you should make a point of reading section 30 on constructing stream ciphers from block ciphers using CFB or OFB modes. You are responsible for this material even though it was not covered in class. Please feel free to ask me or the TA about anything that isn't clear, both in this section and elsewhere.

• 25 Sep. I've posted notes for Lecture 4 and Lecture 5.

• 24 Sep. I've corrected the README file for the Problem Set 1 data. It contained an incorrect analysis of the cryptanalysis algorithm for the half_a_freq.dat data file. I had originally thought the probability that a random 3-letter message would be correctly decoded was 3/4. Upon a more careful analysis, the correct probability is 1/2 + 3/25 = 0.62.

• 23 Sep. Four frequency tables have been posted to Zoo directory /c/cs467/course/assignments/ps1 for use in Problem Set 1. Two are test files; the other two are actual letter frequencies derived from two major works of literature, Shakespeare's The Merry Wives of Windsor, and James Joyce's Ulysses. You should run your program on both of these files in order to get a feeling for the sensitivity of your results to variations in the observed letter frequencies. See the README file in the same directory for information on the two test files.

• 19 Sep. Problem Set 1 is available. It is due before midnight on Tuesday, September 26.

• 17 Sep. I've made major revisions to the notes for Lecture 2 (now at revision 2) and Lecture 3 (now at revision 1). Lecture 2 has two new sections on the probabilistic model and statistical independence that were discussed briefly in class but omitted from the earlier revision of the notes. Lecture 3 reflects more closely the topics actually covered in class.

• 13 Sep. I've posted notes for Lecture 2 and Lecture 3.

• 6 Sep. I've posted draft notes for Lecture 1. When possible, I will post draft notes in advance of the lecture and revised notes afterwards. Each new revision will carry a revision number so you can easily tell whether a copy on hand is the latest or not. The draft version will be designated revision 0.

• 4 Sep. Welcome to the CPSC 467a web site. Look here for announcements and course materials.

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• 4 Sep. A final examination will be given at the officially scheduled time, Tuesday, December 19, 9:00 am. Please take this into account when making your end-of-term travel plans. I do not plan to give an early exam for the convenience of those who want to leave campus early.