Cryptanalysis (SS 2023)

Course Number 705068 and 705069 | Sommersemester 2023

Cryptanalytic attacks and how they guide cryptographic design

Content

Cryptanalytic attacks define the security of cryptographic algorithms, and understanding them is crucial to understand cryptographic design. This lecture aims to give you some in-depth knowledge of several recent state-of-the-art topics in cryptography, with a focus on cryptanalysis:

  • Classic and quantum algorithms for factoring and discrete log
  • Cryptanalysis of block ciphers (differential, linear, algebraic)
  • Cryptanalysis of hash functions and stream ciphers
  • Lattices and continued fractions in cryptanalysis

In the exercises, you will implement some of these attacks to solve cryptanalytic challenges. In the seminar, additional selected topics may be presented by participants — see below for a list of suggested topics.

Material

Lecture and Seminar

Date Who Lecture (16:00-17:30 16:15-17:45 in HS i1) Video (2021)
02.03.2023 ME L1 – Discrete Logarithm YouTube
09.03.2023 ME L2 – Factoring and Continued Fractions YouTube
16.03.2023 MN L3 – Quantum Cryptanalysis YouTube
23.03.2023 RW L4 – Lattices YouTube
30.03.2023 ME L5 – Linear Cryptanalysis YouTube
20.04.2023 MN L6 – Differential Cryptanalysis YouTube
27.04.2023 ME L7 – Advanced Differential Attacks YouTube
04.05.2023 ME L8 – Sponges & Stream Ciphers YouTube
11.05.2023 HH L9 – Algebraic Attacks YouTube
25.05.2023 MN LA – TLS security & Protocol Attacks YouTube
01.06.2023 you Seminars (TB)
15.06.2023 you Seminars (T2, T9)
22.06.2023 you Seminars (TC, T3)
29.06.2023 you Exam

We have two guest talks this year by Roman Walch (L4) and Hosein Hadipour (L9).

Previous versions of this course: SS 2022, SS 2021 (YouTube playlist), SS 2020

Exercises

Date Topic Where
16.03.2023 Team registration deadline TeachCenter
16.03.2023 T1 – Asymmetric Cryptanalysis After L3 in HS i1
20.04.2023 T1 – Submission deadline (23:59) git
28.04.2023 T1 – Assignment interviews (individual slots) Office
27.04.2023 T2 – Symmetric Cryptanalysis After L7 in HS i1
01.06.2023 T2 – Submission deadline (23:59) git
tbd T2 – Assignment interviews (individual slots) Office

Administrative Information

For questions outside lecture times, contact us via the #cryptanalysis Discord channel or by email.

Exercises (KU)

In the exercises, you implement cryptanalysis techniques from the lecture in teams of 2. To get a grade, you submit your implementations for 2 assignments, which we will discuss with you in a final interview (“Abgabegespräch”). Use TeachCenter to register your team and git for your submissions. We usually won’t need the 16:30–17:15 KU timeslots (except for question times and seminar presentations).

Lecture exams and seminar talks (VO)

There are 2 ways to get a grade for the VO:

  • Exam mode: Write exam at the end of the term or take an oral exam later. Register for an exam date in TUGRAZonline or contact us if none is available.
  • Seminar mode: Participate actively in KU+VO and give a seminar presentation in one of the last lectures (30 minutes) accompanied by a short report (8 pages) in your team, for example on
    • Block Ciphers: Division Property | MitM and Biclique Attacks | Boomerang Attacks | …
    • Hash Functions: Rebound Attack | Cryptanalytic Exploits (MD5 Certificates etc.) | …
    • Authenticated Encryption: Security Proofs and Robustness | …
    • RSA: (In)Security in Practice | Secure Key Generation | …
    • Post-Quantum: Coding-based Cryptography | Lattices and Learning with errors | …
    • Implementation Security: Secure Masking | Statistical Ineffective Fault Attacks | …

Grading

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 to the strictest extent possible.

Literature

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:

Lecturers

Maria Eichlseder
Maria
Eichlseder

Assistant Professor

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Marcel Nageler
Marcel
Nageler

PhD Student

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