CS255: Introduction to Cryptography

Course Overview

Winter 2015


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), message integrity, digital signatures, user authentication, key management, cryptographic hashing, Network security protocols (SSL, IPsec), public-key infrastructure, digital rights management, and a bit of zero-knowledge protocols.

Prerequisites:   The course is self contained, however a basic understanding of probability theory and modular arithmetic will be helpful. The course is intended for advanced undergraduates and masters students.

Textbook Information

The following books can be used to supplement the lectures:

Note that the textbooks do not cover all the material discussed in class.


  • There will be a number of sections given by the TAs during the quarter.
  • Bi-weekly sections will be held on Fridays in Thornton 102 at 3:15pm-4:05pm.
  • Attendance at the sections is optional.

Homework Assignments

  • There will be three written homework assignments and two programming projects.
  • 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 three homework assignments and both 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. There will be no additional extensions.
  • Homework will be due on the due date in class or at 5pm under David's office door (Gates 492).
  • 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:

0.35 H + 0.35 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.

Students with Documented Disabilities

Students who may need an academic accommodation based on the impact of a disability must initiate the request with the Student Disability Resource Center (SDRC) located within the Office of Accessible Education (OAE). SDRC staff will evaluate the request with required documentation, recommend reasonable accommodations, and prepare an Accommodation Letter for faculty dated in the current quarter in which the request is being made. Students should contact the SDRC as soon as possible since timely notice is needed to coordinate accommodations. The OAE is located at 563 Salvatierra Walk (phone: 723-1066).