Math5248, Cryptology and Number Theory,
Lec 002 Fall 2009 Course Page


Location and time: LindH 229, 02:30 P.M. - 03:45 P.M. , Tu,Th
Lecturer: John Baxter, office Vincent Hall 254
(612) 624-9851
baxter@math.umn.edu
Textbook: Crypto,
by Paul Garrett (available now at Alpha Print, 1407 Fourth Street SE, Dinkytown, 612-379-8535).
We will only cover some of topics in this text. Chapters 1--13 will be the main focus. Some additional material might be presented in the lectures.
The goal of the course is to understand the mathematics underlying modern cryptology (the theory of encryption and decryption of messages). Besides discussing cyphers, our emphasis will be on the relevant parts of number theory, together with some other topics from algebra.
Background reading: The web page of Bruce Schneier is an excellent source of current information about computer security, including cryptography. His newsletter is also available there.
Homework assignments, exam schedules and any extra notes will be posted to this page later. 40% of the grade will be based on two midterm (take-home) exams (20 % for each exam), 30% of the grade will be based on homeworks, and 30% will be based on the final exam (probably in-class).
All tests and examinations will be open-book, open notes, calculators allowed.
Web Calculator page 1 ... Web Calculator page 2 ... Wolfram Alpha
Vigenere Calculator page ... Factoris
midterm examination 1:a take-home exam starting Thursday, October 15, 2009, due on Tuesday, October 20, 2009.
This exam will cover: all sections from Chapter 1 and Chapter 3, sections 1, 2, and 5 from Chapter 4, sections 2 and 3 from Chapter 6, sections 1 and 2 from Chapter 7, sections 1, 2, 3, 5 from Chapter 23 (Groups), the online notes about probability and frequency, and the treatment of Euler's Theorem, Fermat's Theorem and the Euler phi-function given in class.
the exam updated 6:50 am October 16. correction to Problem 1(a). ... solutions for midterm 1 .
midterm examination 2 : a take-home exam starting Tuesday, December 1, 2009, due at the beginning of class on Tuesday, December 8, 2009.

final examination will be a take-home exam, dates to be set soon.
Probability and Frequency ... the Euler phi-function ... Simultaneous congruences
Lecture for Monday, November 16 (Quadratic Reciprocity)
Gauss's Lemma ... Prime Powers
Assignment 1, due Thursday, September 17.
Solutions
Assignment 2, due Thursday, October 1. Updated with more detailed instructions
Solutions
Assignment 3, due Thursday, November 5. (updated)
Solutions
Assignment 4, due Tuesday, November 24. (Extra problem added. Extra problem should be done but not handed in.)
Feedback and Questions
It is very useful to get feedback and questions, both during and outside class. Office hour times will posted on my homepage after the start of classes. You can also make appointments to see me at other times. If you are near my office at any time you are welcome to stop in and check whether I am available. If I am busy we will schedule another time.
general information for all courses:
Incompletes: The Department policy is: The grade of "I" is assigned when a student has satisfactorily completed all but a small portion of the work of the course and has made arrangements to make up the work. You cannot get a grade of "I" just because you are behind in your work or it appears that you are failing the course.
Student Conduct: Academic honesty and respect for others are required in every course. Students are expected to follow the university policy on student conduct. Instructors and students are expected to follow the university policy on class expectations.
For an explanation of the general grading system of letter grades see the university grading policies.