TMA4160 Cryptography - Fall 2020

Lecturer: Jiaxin Pan
Assistant: Shuang Wu
Schedule Room
Lectures: Thursday 12:15-14:00 see the schedule
Friday 10:15-12:00
Exercises: Wednesday 16:15-17:00
Visiting hours: Thursday 14:00-15:00 836 in SBII
Exam: 16.12.2020


23.08.2021: Resit exam and its answers are uploaded here

19.11.2020: There won't be any so-called control interview.

17.11.2020: This week's lecture will be on zoom. Link can be found in the blackboard.

05.11.2020: Please also be aware of the messages in Blackboard.

05.11.2020: There is no lecture on 06.11. and 13.11..

30.10.2020: (Partial) Answer to Homework of Week 35: Exercise 3. Only c) and d) are not secure PRGs.

28.10.2020: Please check the Blackboard message "Til alle studenter i TMA4160"

16.10.2020: For the twin Diffie-Hellman part of today's lecture, it is mostly from In particular, the answer to Exercise 10.14 (in BS) is the proof of Theorem 2, and the discussion of Twin Hashed ElGamal is from Section 4. I think my note explains well. You could read the original paper for more details.

08.10.2020: For tomorrow's lecture, it would be good if you could have a look at Exercise 11.14 (a and c) and Exercise 10.14 in BS.

02.10.2020: Reference group meeting and response.

  • Comment 1: It would be better to provide a clear overview of material used in the lecture.
    • Response: In the lecture plan, there is a column mentions the material used in the corresponding week's lectures. But it is a bit brief and I sometimes made meaningful minor changes during the lecture rather than "repeating" the lecture notes. To be more precise about this, in the Blackboard system, there is a detailed summary of each week's teaching.
  • Comment 2: It would be better to slow down the speed of writing on the "white board" (:= iPad) and have a good balance between writing and speaking.
    • Response: I will pay attention to it. I needed to adjust when I switched frequently between looking at iPad and the audience. I will try to improve it.
  • Comment 3: It would be good to post the slides before the lecture.
    • Response: I preferred to use hand-writing a few weeks ago, since it can help me to slow down my speed and it was also suggested by some of you. And it is also for logistic reasons.
  • Comment 4: The lectures explained very well about the concepts and intuitions of the contents. It would be better to explain a bit more about the details. For instance, some details were not entirely obvious. It would be good to have some more examples.
    • Response: It is a very good suggestion. I will put more focus on the important details. Moreover, I will select some important exercises (from your homework) as examples to explain during the lectures. It is worth mentioning that this semester's exam will be different to the old exams to refer the different focuses of our lectures. Exercises in our homework do reflect our focuses, in particular, those we have discussed during the lectures. Thus, when you later prepare for the exam, please pay attention to the homework and those explained during the lectures, rather than the old exams. Nevertheless, the old exams are still beneficial.
  • Comment 5: The current wiki page is very nice. It would be better to post contents in the wiki rather than the Blackboard.
    • Response: It is please to know. I will keep both pages updated. In particular, I will post the detailed summary in the Blackboard. I find it distracting to post too many messages in the "Message" channel in the wiki.

18.09.2020: As a reminder, catalogue for stream/recordings of our lectures is:

07.08.2020: Our lecture starts from Week 34.

06.08.2020: Some notices:

  • Our course will be taken place as usual, namely, on campus. However, this may change overtime. If you plan to take the course, but suspect that it is not possible for you to attend the lectures in person (for instance, you are in a risk group and shouldn't meet too many other people), please let me know via email. Or if this happens during the semester, please also send me an email.
  • We may post some additional notes (which is used in the teaching or simply useful) in our blackboard system. Then I will let you know here.


You should be familiar with basic abstract algebra such as groups, rings and fields.

You will find the lectures more interesting or enjoyable if you know something about computational complexity and the analysis of algorithms. Using a computer algebra system (or equivalent) is required for some of the programming homework. Previous experience with computer algebra systems is helpful, but not required.

Reference group

Deleted due to GDPR.

Course material

Changes: Please note that this semester we will make changes to the previous lecture, namely, our curriculum will reflect basic concepts in modern cryptography. It will put more focus in cryptographic constructions (for instance, public-key encryption) and its proofs rather than cryptanalysis (for instance, algorithms for solving discrete logarithms). We will have a good balance between informal intuitions and formal definitions and proofs. We may also cover some interesting applied topics if there is time.

Lecture notes: All our lectures are based on material available online, either the following notes or some additional notes (or slides) in our Blackboard system. It will be mentioned explicitly in the class and lecture plan.

  • The previous lecture notes follow some of the lectures, but it mainly focuses on intuitions. It may be updated throughout the course.
  • Some of our lectures will follow the notes from Boneh and Shoup as well. It is written in a more formal manner and in the style of modern cryptography.

Again, we will announce which contents a lecture is based on during the lecture, and we will state it in the lecture plan.


You should be able to get by with just the lecture notes (and possibly the supplements), but some of you may find Stinson or the book of Katz and Lindell useful. Note that they do not cover the entire curriculum.

The curriculum is defined to be the material covered by the lecture notes, the lectures and the exercises.

2023-09-21, Jiaxin Pan