We will begin with a brief discussion of "classical" cryptography and its limitations. Following this, we will define a notion of "perfect" security and see what can and cannot be achieved in this sense. This will lead us naturally to the modern, complexity-theoretic appraoch to cryptography in which security is based on the assumed

No advanced mathematics background is assumed, but students are expected to possess "mathematical maturity" since many of the concepts will be abstract and rigorous proofs will be given occasionally throughout the semester. Discrete mathematics (probability theory, modular arithmetic) and complexity theory are also helpful, but the necessary prerequisites will be discussed in class.

A graduate cryptography course will be offered next semester (Spring, 2003). The graduate course will not assume that students have taken the undergraduate course; therefore, there will be a fair amount of overlap between the two. In any case, I welcome students who wish to take both. The graduate version will cover more material in far greater depth, will assume slightly more mathematical background, and will focus more on rigorous proofs of security. If you have questions about which version is "right" for you, please see me.

- The class meets Monday, Wednesday, and Friday from 10-10:50 in 1121 CSIC.
- The textbook for the course is "Cryptography: Theory and Practice, 2nd edition" by Stinson.
*The second edition is very different from the first edition. Please do not use the older version of the book.*Additional readings will be listed on the course homepage. **Grading**will be based on 6-7 homeworks assigned throughout the course (40%), a midterm (25%), and a final exam (35%).*Note that homeworks make up a significant portion of the final grade!***Graduate students**taking the course (both Masters and PhDs students) will be required to do additional problems for homework. Their grades will also be curved independently of those of the undergraduate students.**Homework**- You may collaborate on the homeworks with at most one other student in the class. Each student must independently write up their own solutions. Cheating will not be tolerated!
- You may consult outside references when doing the homework, as long as these sources are properly referenced, you write up the solution yourself, and
*you understand the answer*.

- Feedback is very important. Please let me know (via email, if you like) if anything covered in class is unclear. Most likely, other students are having the same difficulty.
- Check the course homepage frequently since all handouts will be distributed via the web and an updated syllabus will be maintained on this page.

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