Cryptography (WS 2021/22)

Content

Cryptography is the mathematical backbone of information security. This lecture covers the most important building blocks modern cryptographic protocols and their security, including:

• Authenticated Encryption, hashing, and symmetric primitives (AES-GCM, SHA-3, …)
• Asymmetric encryption and digital signatures (RSA, DH, DSA, ECC, post-quantum crypto, …)
• Authentication and key-exchange protocols, including an introduction to advanced privacy-preserving protocols

For all these building blocks, we will have a look at the design ideas and goals behind the algorithm, its security properties in practice, and some cryptanalysis techniques such as differential cryptanalysis. We will cover the necessary mathematical and methodical background so that you can try your own hands in the exercises at breaking ciphers to gain a deeper understanding of their design.

COVID-19 Info

The lecture (VO) is in presence in HS i1 as long as this is practical (green/yellow), subject to the TU Graz hygiene rules (3G required, TU Graz greenlight recommended). Recordings of all lectures from last year are available for those students who can’t attend in person. If on-campus teaching becomes impractical (orange/red), we’ll switch to virtual YouTube streaming. The written VO exam is in presence in the central exam weeks. As an alternative, oral virtual exams are possible at any time for those unable to attend in person. For the weekly exercises (KU), the default is in presence in small groups (3G) as long as this is practical. For those unable to attend, one virtual Discord group is available for registration in TUGRAZonline. The two written KU exams are in presence for all groups (see below for exceptions and backup plans). Use Discord for questions, updates, etc.

Material

Date	Who	Lecture 15:15–17:00 (HS i1)	Practicals 14:00–15:00
01.10.2021	ME	L1 – Introduction	–
08.10.2021	ME	L2 – Symm. Primitives 1 – Block Ciphers & Friends	T1, py sekelton
15.10.2021	ME	L3 – Symm. Primitives 2 – Lightweight Crypto	T2
22.10.2021	ME	L4 – Symm. Primitives 3 – Cryptanalysis	T3
29.10.2021	ME	L5 – Symm. Modes 1 – Authentication	T4
05.11.2021	ME	L6 – Symm. Modes 2 – Encryption	T5
12.11.2021			KU Exam 1
19.11.2021	ME	L7 – Asymmetric Primitives 1 – Factoring, RSA	T6
26.11.2021	ME	L8 – Asymmetric Primitives 2 – Discrete Log, ECC	T7
03.12.2021	DK	L9 – Asymmetric Primitives 3 – PQC	T8
10.12.2021	DK	LA – Protocols 1 – Authentication, Key Exchange	T9
17.12.2021			–
Holidays			–
07.01.2022	DK	LB – Protocols 2 – Advanced Protocols, Privacy	TA
14.01.2022	DK	LC – Outro	TB
21.01.2022			KU Exam 2
28.01.2022		VO Exam (Example Questions)	–

The lecture slides are reasonably self-contained, but often briefly phrased.
If you prefer full-text resources, you may find some of the following books interesting:

• Serious Cryptography, by J.-P. Aumasson
• Introduction to Cryptography with Coding Theory, by W. Trappe, L.C. Washington

Previous version of this course: WS 2020/2021 (YouTube playlist), WS 2019/2020

Administrative Information

Lecture Exams (VO)

The VO exam is a written exam (for the main exam dates; alternatively, you can contact us for an oral exam any time). We will ask 4 questions on different topics; you can find lists of example questions to test yourself on the last slide for each lecture. Please find the exam dates and registration in TUGRAZonline.

Exercise Sheets (KU)

We recommend to visit the KU and VO of Cryptography in the same semester. In the exercises, you practice the new topics in weekly exercise classes. The tasks are handed out after each week’s lectures, and due for the exercises of the following week, where one student will be selected to present the solution for each of the tasks. Thus, presence is mandatory if you tick any tasks. You need to solve 50% of all examples to complete the KU. Use the TU Graz Teach Center to tick the tasks you solved before each class. If you solve more than the required 50%, we will reward you with bonus points that are added to your exam results – for details, please check the lecture slides. Most of the exercises are pen-and-paper thinking exercises, but each sheet includes a bonus challenge that will require some programming. COVID-19 rules: You can optionally register for a presence group (lecture hall) or a virtual group (Discord) in TUGRAZonline. Presence groups will also switch to a virtual mode if necessary (orange/red).

Exercise Exams (KU)

The grades for the KU are based on two exams (and the required 50% tick rate), plus bonus tasks. The dates and place are announced on this website. All students that participate at least in the first exam will receive a grade (positive or negative). There will be a “second-chance” exam at the end of the term. For details on the conditions, check the slides of the introductory lecture or ask us. COVID-19 rules: KU exams are in presence for all groups. In case this is impossible, they move to a virtual mode supervised on Discord or WebEx. In case you are unable to join the main exam dates (e.g., sick, quarantine), there is a backup slot in February.

Lecturers