CS 255 Course Overview

(Winter 2005)



This course is an introduction to the basic theory and practice of cryptographic techniques used in computer security. We will cover topics such as encryption (secret-key and public-key), digital signatures, secure authentication, key management, cryptographic hashing, Network security protocols (SSL, IPsec), PKI, copyright protection, and a bit of zero-knowledge protocols.


The course requires a basic understanding of probability theory. Some knowledge of modular arithmetic will be helpful but not required. The course is intended for advanced undergraduates and graduate students.

Textbook Information

We will be using the following books:

  • Cryptography Theory and Practice, Second edition by D. Stinson.
  • Optional: Cryptography and Network Security, Third edition, by William Stallings.
  • Optional: Handbook of Applied Cryptography by A. Menezes, P. Van Oorschot, S. Vanstone.    Free!
  • Optional: Applied cryptography by B. Schneier.

and research papers handed out in class.


  • There will be four sections given by the TA during the quarter.
  • Sections will be held on Fridays in Gates B03 at 9:00am - 9:50am (Live on E2)
    • January 21,
    • February 4,
    • February 18,
    • March 4,
  • Attendance at the sections is optional.

Homework Assignments

  • There will be four written homework assignments and two programming projects. All programming projects will be in Java using the JCE.
  • You may collaborate when solving the written assignments, however when writing up the solutions you must do so on your own. 
  • Both programming projects can be done in pairs.
  • You must hand in all four homework assignments and the two programming projects.
  • Some of the assignments will contain extra credit questions. You must solve extra credit questions on your own.
  • Extensions:  each student has a total of 72 extension hours throughout the quarter. This automatic extension can be spent in units of 24 hours on any of the assignments and projects. Please mark the submission time for any late assignment.
  • Homework will be due on Wednesdays in class or at 5pm in the CS255 homework bin next to Gates 182.
  • It is an honor code violation to consult solutions to homework problems from previous CS255's.


There will be an in class final exam during finals week. No midterm exam.
Students can choose from one of two dates for the in class final exam. We will announce the date for the alternate final as soon as we have it.


Final placement in the class will be determined by the following formula:

0.4 H + 0.3 P + 0.3 F

  • H is your average score on the four written homework assignments.
  • P is the weighted average grade on the two programming projects.
  • F is your final exam score.