CS 178: Introduction to Cryptography (Winter 2017)

General Information

Instructor: Huijia (Rachel) Lin, rachel.lin(at)cs(dot)ucsb(dot)edu

TA: Priayanka Bose, priyanka (at) cs (dot) ucsb (dot) edu

Reader: Kirti Bhandari, kirtibhandari (at) umail (dot) ucsb (dot) edu

Time and location:

  • Class: Monday/Wednesday 11am-12:15pm, PSYCH 1902
  • Session 1: Friday 9:00-9:50am, 387 104
  • Session 2: Friday 2:00-2:50pm, PHELP 3525

Office hours:

  • Priayanka Bose: Tuesday 3:00pm- 5:00pm, Trailer 936
  • Rachel Lin: Wednesday 4:30pm-5:30pm, HFH 1153

Piazza: We will be using Piazza for class-related discussions, posting homework and materials, and announcement. The Piazza page for this class is available at https://piazza.com/ucsb/winter2017/cs178/home.


Cryptography provides important tools for ensuring the privacy, authenticity, and integrity of the increasingly sensitive information involved in modern digital systems. Nowadays, core cryptographic tools, including encryption, message authentication codes, digital signature, key agreement protocols, etc., are used behind millions of daily on-line transactions. In this course, we will unveil some of the "magic" of cryptography.

Modern Cryptography uses mathematical language to precisely pin down elusive security goals, design primitives and protocols to achieve these goals, and validate the security of designed primitives and protocols using mathematical proofs based on clearly stated hardness assumptions. Therefore, to learn cryptography, it is essential to understand its mathematical underpinning. In this class, we will see the inner-working of cryptography for several core cryptographic tools, from encryption, to message authentication codes, to hash functions, to digital signatures, etc.

Required background: Though the presentation in this class will largely remain at an intuitive level, the class still requires a certain level of mathematical maturity (students should be ready to understand mathematical definition and proofs, and to write simple ones). Exposure to basic probability, algebra / elementary number theory and theory of computing is also expected. If in doubt, contact the instructor!

Textbook and Resources

There is no mandatory textbook. The class will take contents from the following textbook and lecture notes. The instructor will post reading material after each class. Additional great resources that will help you to learn are:


There will be five homework, one midterm exam, and one final exam. Each homework accounts for 10% points, midterm 20% points, and final 30% points. Your final grade will depend on the weighted total points, and your ranking in the class.

Class Policy:

  • Every homework will be posted on-line on days indicated below in the syllabus by 11:59pm PST, and are due on days indicated below at 4:00pm PST. The homework can be submitted at the beginning of the class or to the homework box in the CS mail room.
  • Students can form groups of 3 (or less) to discuss about the homework. But each student must write down his/her own solution and acknowledge the collaborators.
  • The midterm and final exams must be completed independently. The only material allowed during the exam are 2 pages of hand-written notes. If additional material is allowed, the instructor will communicate before the exams.


The following is a rough list of topics to be covered in the class. This list will be changed and refined during the course depending on the pace of the class.

WeekDateContentReading MaterialAssignment
1 2017-01-09
  • Administration
  • Introduction to Cryptography
  • Block-Cipher
  • Pseudo-random functions
  • Homework 1 out
2 2017-01-16
  • Holiday, no class
  • Class Cancelled
3 2017-01-23
  • Symmetric Key Encryption
  • Modes of Opeartion
  • Homework 1 due
  • Hash Function
  • Homework 2 out
4 2017-01-30
  • Message Authentication
  • Public Key Encryption
  • Computational Number Theory
5 2017-02-06
  • El Gamal and RSA
  • Homework 2 due
  • Homework 3 out
  • El Gamal and RSA, II
6 2017-02-13
  • Signature Schemes
  • Certificates
  • Homework 3 due
  • Homework 4 out
7 2017-02-20
  • Holiday, no class
  • Midterm, in class
8 2017-02-27
  • ZK proofs, I
  • ZK proofs, II
  • Homework 4 due
  • Homework 5 out
9 2017-03-06
  • Fully Homomorphic Encryption, I
  • Fully Homomorphic Encryption, II
10 2017-03-13
  • Fully Homomorphic Encryption, III
  • Homework 5 due
  • Wrapping up
  • Q & A
11 2017-03-23
  • Final 12:00-3:00pm