CS 5830: Cryptography
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Syllabus for CS 5830

Welcome to CS 5830, Cryptography. We will be studying cryptography and how to use it in practice. By the end of the course you should understand not only the basics of cryptography, but how to implement suitable cryptographic algorithms within broader projects. You'll also get a taste of modern theoretical cryptography here and there, but this course will not focus on theory and no higher-level mathematics will be needed.

A key aspect of the course will be implementing cryptographic schemes, as well as showing how to break poorly designed or implemented schemes. Some homeworks will target feature requests in a widely used cryptography library, bonus points will be awarded for pull-worthy code.

Instructor: Tom Ristenpart (https://rist.tech.cornell.edu) TA: Paul Grubbs (https://www.cs.cornell.edu/~paulgrubbs/)


Students should have programming experience (we will be focusing on Python), understand basic probability, know binary representations (ASCII), operations on bit strings (XOR), have some background on computer networking, file systems, etc. If in doubt shoot the instructor an email.


The class will involve a combination of lectures, in-class group exercises, homeworks, a prelim, and a final. You'll be graded according to the following:

  • Participation: 10%
  • Homeworks: 50% (each homework will count an equal amount)
  • Prelim: 20%
  • Final: 20%

There will be several opportunities for extra credit, as well.

Background reading

The following books should be helpful, but none are required if you don't want to spend the money:

Lecture schedule

A very preliminary schedule is below to give a taste of the scope of what we're hoping to cover. Homeworks will be due on the due date by 11:59:59pm EST. You can use in total 3 late days throughout the semeseter.

Date Topic Note
Jan 26 Intro & one-time-pads Slides
Jan 31 OTP Slides
Feb 2 CTR mode, computational indistinguishability & reductions Slides
Feb 7 Block ciphers Slides
Feb 9 Class cancelled (snow day)
Feb 14 Block cipher modes, CBC mode Slides
Feb 16 Padding oracle attacks Slides
Feb 21 No Lecture (February break)
Feb 23 Authenticated encryption, Message authentication Slides
Feb 28 Hash functions, HMAC Slides
Mar 2 Guest lecture: Paul Kehrer
Mar 7 Password-based AEAD Slides
Mar 9 TLS & TLS record layer Slides
Mar 14 Campus closed
Mar 16 Overview of practice midterm
Mar 21 In-class midterm
Mar 23 Overview of midterm
Mar 28 Paul's lecture on unit testing
Mar 30 RSA Slides
Apr 4 No lecture (Spring break)
Apr 6 No lecture (Spring break)
Apr 11 Key exchange & Diffie-Hellman Slides
Apr 13 Digital signatures & PKI Slides
Apr 18 Discrete log based digital signatures Slides
Apr 20 ECC crypto Slides
Apr 25 Hybrid encryption & ElGamal Slides
Apr 27 RNGs Slides
May 2 Cryptographic backdoors Slides
May 4 Summary & Internet Censorship Slides
May 9 (Tom traveling)