CSIC 4331/6331 - Cryptography

Mondays, 12:45-3:15
Monroe Hall B32

Instructor Information

Name: Arkady Yerukhimovich
Email: arkady@gwu.edu
Office: SEH4570
Office hours: Monday 3:30-5:00, Wednesday 3:00-4:00

Course description

This course will introduce students to modern cryptography with a focus on formal definitions and provably secure constructions of cryptographic protocols. Topics covered will include secret-key and public-key encryption, message-authentication codes, digital signatures, and advanced topics. See syllabus for additional details.


Jonathan Katz, Yehuda Lindell: "Introduction to Modern Cryptography. Second Edition." CRC Press 2014. (Available on Amazon)


Exam 125%(10% floating)
Exam 225%
Class participation10%

Homework policy

Homeworks will be assigned approximately every two weeks. Homeworks are due before class (by 12:45PM) on the due date. They must be submitted via Blackboard by this time to receive credit. Homeworks can be typed using your favorite tool (I am happy to help anybody interested in learning LaTex) or handwritten and scanned. But, make sure that what you submit is legible as it is what will be graded. No late homeworks will be accepted!

Students are welcome to work together on homeworks, however each student must write up and submit their own solutions. If you work on the homework with someone else, you MUST acknowledge them on your submitted homework.

Additionally, you may use outside resources (e.g., web search, other text books, lecture notes) to help with the homework. However, if you use any such resource, you MUST cite them appropriately. Moreover, the solutions you submit MUST be your own. Make sure to write-up your own answers and that you understand them, copying and pasting solutions is not acceptable. Submitted homeworks violating these guidelines will be considered in breach of the academic integrity code and will be prosecuted accordingly.

There will be 6-7 homework assigments over the course of the semester. The final homework grade will be the average of all homework scores with the lowest score dropped.

Laptop policy

I ask that students not use laptops or other electronic devices in class. I will make sure to lecture at a pace that allows for hand-written notes.

Tentative schedule

This is a tentative schedule for the class. I will update this as we go along. I will also post all homeworks and due dates here.

DateLecture Topic(s)ReadingHW OutHW DueQuiz
Aug. 26Probability review, principles of modern cryptography, perfect secrecy and the one-time padA.3, Chapters 1, 2HW0, HW1Quiz 1
Sep. 2Labor day: no classHW0 due
Sep. 9Asymptotics review, Limitations of perfect secrecy, computationally-secure encryption, proofs by reduction, pseudorandom generatorsA.2, 3.1, 3.2, 3.3HW2HW1 dueQuiz 2
Sep. 16Review of PRG and computationally-secure encryption, Proof of security of PRG+OTP encryption, pseudorandom functions3.3, 3.5.1Quiz 3
Sep. 23CPA security, construction of CPA-secure encryption3.4, 3.5HW2 due
Sep. 30modes of operation, CCA-secure encryption, padding oracle attack, Message authentication codes definitions and construction3.6, 3.7, 4.1, 4.2, 4.3.1HW3Quiz 4
Oct. 7Review MAC definition, CBC-MAC, authenticated encryption, hash function definitions and applications, review for exam4.2 - 4.5, 5.1, 5.6HW3 due
Oct. 14Exam 1 (in class)
Oct. 21Fall break (no class)HW4
Oct. 28Practical constructions of symmetric-key primitives, DES, 3DES, AES, Feistel networksIntro of chapter 6, 6.2 (All except 6.2.6), 6.3.1
Nov. 4Number theory, group theory8.1, B.1.2HW5HW4 dueQuiz 5
Nov. 11Cryptographic assumptions, Key exchange, Public-key encryption, Diffie-Hellman, El Gamal8.3 (except for 8.3.4), 8.4, 10, 11.1, 11.2 (through 11.2.1), 11.4.1 Quiz 6
Nov. 18El Gamal, RSA, Paillier, CCA security11.4.1, 11.5.1, 11.5.2, 13.2HW6HW5 dueQuiz 7 (same as HW problems)
Nov. 25Digital signatures, Hash-and-sign, RSA Signatures, Signatures from hashing12.1-12.4, 12.6, 12.7Quiz 8
Dec. 2Advanced Topics, review for examHW6 due
Dec. 9Exam 2 (in class)


  • NEW: To help with last minute questions before the exam, I will hold office hours on Monday morning 10:00-11:30 AM.
  • Office hours change for week of Nov. 25th will be Monday 3:30-5:00, Tuesday 10:00-11:30. No office hours on Wednesday.
  • HW6 is out. Due Dec. 2 (by 12:45PM)
  • Office hours on Wednesday November, 20 are moved to 2:00PM-3:30PM
  • HW5 is out. Due Nov. 18 (by 12:45PM)
  • HW4 is out. Due Nov. 4 (by 12:45PM)
  • No class or office hours on Monday, October 21. Enjoy your fall break.
  • Office hours for Monday, October 14th are moved to 10:00-11:30AM to enable last minute, exam-prep questions.
  • Our first exam will be in class on Monday, Oct. 14. The exam is closed book and closed notes. But, you are allowed to bring in a single (8.5" x 11") sheet of paper with notes on both sides. The exam will cover all material covered in class and homeworks through the Oct. 7th lecture.
  • HW3 is out. Due Oct. 7 (by 12:45PM)
  • HW2 is out. Due Sep. 23 (by 12:45PM)
  • Office hours for this semester will be Monday 3:30 (after class) - 5:00, Wednesday 3:00-4:00.
  • HW1 is out. Due Sep. 9 (by 12:45PM). I strongly advise people to start early in case you have any questions.
  • HW0 is out. Due Sep. 2 (by 12:45PM)
  • Office hours for the weeks of August 26 and September 2, will be by appointment only. I will pick regular office hours after I receive your HW0 responses. Do not hesitate to email me if you have any questions.
  • For anyone who is a bit rusty on probability, the following lectures give a good introduction to all the concepts we have used thus far: link.
  • Welcome to Cryptography - Fall '19