Cryptography (WS 2024/25)

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.

Material

Date	Who	Lecture 15:00–17:00 (HS i1)	Practicals 14:00–15:00 (HS i1, i5, or i14)
04.10.2024	ME	L1 – Introduction	–
11.10.2024	ME	L2 – Symm. Primitives 1 – Block Ciphers & Friends	T1
18.10.2024	ME	L3 – Symm. Primitives 2 – Lightweight Crypto	T2
25.10.2024	ME	L4 – Symm. Primitives 3 – Cryptanalysis	T3
08.11.2024	ME	L5 – Symm. Modes 1 – Authentication	T4
15.11.2024	ME	L6 – Symm. Modes 2 – Encryption	T5
22.11.2024			KU Exam 1
29.11.2024	ME	L7 – Asymmetric Primitives 1 – Factoring, RSA	T6
06.12.2024	ME	L8 – Asymmetric Primitives 2 – Discrete Log, ECC	T7
13.12.2024	ME	L9 – Asymmetric Primitives 3 – PQC	T8
Holidays			-
10.01.2025	ME	LA – Protocols 1 – Authentication, Key Exchange	T9
17.01.2025	ME	LB – Protocols 2 – Advanced Protocols, Privacy	TA
24.01.2025			KU Exam 2
		VO Exam	-

All lecture videos from WS 2020/2021 are available as a YouTube playlist.

If you want to TeX your assignment sheet solutions for the practicals, find the LaTeX source here.

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 versions of this course: WS 2023/2024, WS 2022/2023, WS 2021/2022, WS 2020/2021 (YouTube playlist), WS 2019/2020

Administrative Information

Our communication channel for questions is Discord.

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 TeachCenter 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. Generally, if you tick a task, you must attend the corresponding exercise class on-campus (otherwise, attendance is not required). Alternatively, up to 2 times per semester, you may instead hand in your written, well-readable solution (schriftliche Ersatzabgabe) of all tasks you ticked to your tutor in case you cannot attend a class (e.g., due to Corona). In this case, your tutor may decide to request a short 10-minute virtual assignment interview via Discord on one of the tasks you ticked. We treat the involvement of ChatGPT and similar tools the same way as the involvement of another natural person. That is, for involvement that qualifies as plagiarism or an impermissible level of assistance, the consequences will be the same in both cases.

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 is a "second-chance" exam in February where you can re-take a KU exam (e.g., if you missed the main date or it didn't go so well).

Lecture Dates

Date	Begin	End	Location	Event	Type	Comment
2025/01/10	14:00	15:00	HS i1	Abhaltung	KU	fix/
2025/01/10	14:00	15:00	HS i14	Abhaltung	KU	fix/
2025/01/10	14:00	15:00	HS i5	Abhaltung	KU	fix/
2025/01/10	15:00	17:00	HS i1	Abhaltung	VO	fix/
2025/01/17	14:00	15:00	HS i1	Abhaltung	KU	fix/
2025/01/17	14:00	15:00	HS i5	Abhaltung	KU	fix/
2025/01/17	14:00	15:00	HS i14	Abhaltung	KU	fix/
2025/01/17	15:00	17:00	HS i1	Abhaltung	VO	fix/
2025/01/24	15:00	17:00	HS i11 "SIEMENS Hörsaal"	Abhaltung	KU	fix/
2025/01/24	15:00	17:00	HS i2	Abhaltung	KU	fix/
2025/01/24	15:00	17:00	HS i1	Abhaltung	KU	fix/

Lecturers