Applied Cryptography 2

Course Number 705064 and 705065 | Sommersemester 2020

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. Topics to be covered include:

  • Modern algorithms for factoring
  • Cryptanalysis of block ciphers
  • Cryptanalysis of hash functions
  • Algebraic attacks
  • Lattices and continued fractions in cryptanalysis
  • Multi-party computation

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 slides

Date Topic Download
07.03.2019 L1 – Factoring and Continued Fractions Slides
14.03.2019 L2 – Secure Multi-Party Computation 1 Slides
21.03.2019 L3 – Secure Multi-Party Computation 2 Slides
28.03.2019 L4 – Linear Cryptanalysis Slides
04.04.2019 L5 – Differential Cryptanalysis Slides
11.04.2019 L6 – Algebraic Attacks Slides
02.05.2019 L7 – Hash Function Cryptanalysis Slides
09.05.2019 L8 – Advanced Differential Attacks Slides
16.05.2019 L9 – Lattices Slides
Conclusion Slides
Exam Questions Questions

Seminar

Date Topic Download
Seminar Schedule Assignment
16.05.2019 S1 – Lattices: The NTRU Cryptosystem SlidesJupyter example
23.05.2019 S2 – Asymmetric Cryptography: Discrete Logarithm Problem Slides
23.05.2019 S3 – Elliptic-Curve Cryptography: Advanced Topics Slides
06.06.2019 S4 – Homomorphic Encryption Slides
06.06.2019 S5 – Error-Correcting Codes and Cryptography Slides
13.06.2019 S6 – Password Hashing Slides
13.06.2019 S7 – The Importance of Context Slides

Exercises

Date Topic Download
21.03.2019 T1 – Asymmetric Cryptanalysis and MPC AssignmentSlidesAssignment Files
11.04.2019 Q1 – Asymmetric Cryptanalysis Question Session
TS – Seminar Assignment
09.05.2019 T2 – Symmetric Cryptanalysis AssignmentSlides
06.06.2019 Q2 – Symmetric Cryptanalysis Question Session

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:

Administrative Information

Important dates and deadlines

Date Event
04.03.2019 VO/KU registration deadline (TUGRAZonline)
21.03.2019 Team registration deadline (STicS)
21.03.2019 Assignment 1 release
11.04.2019 Assignment 1 question time
02.05.2019 Assignment 1 submission (23:59)
09.05.2019 Assignment 2 release
06.06.2019 Assignment 2 question time
13.06.2019 Assignment 2 submission (23:59)
27.06.2019 VO written exam

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 the Student Tick System (STicS) to register your team and upload 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
  • Seminar mode: Participate actively in KU+VO and give a seminar presentation in one of the last lectures (45 minutes)

You can find the exam dates and registration in TUGRAZonline.

Suggested seminar topics include:

  • Discrete Logarithm Problem
  • Block Ciphers: MitM Attacks, Biclique, etc.
  • Block Ciphers: Lightweight Crypto
  • Block Ciphers: Statistical Attacks
  • Block Ciphers: Division Property
  • Hash Functions: Multi-Collisions
  • Hash Functions: Rebound Attack
  • Authenticated Encryption: Modes, Robustness, Security notions, etc.
  • Authenticated Encryption: Permutation-based Cryptography, Tweakable Block Ciphers, etc.
  • Algebraic Attacks: Gröbner Basis, etc.
  • Elliptic-Curve Cryptography: Advanced topics
  • Lattices: The NTRU cryptosystem
  • Lattices: Learning with errors
  • Selected Topics: Tools in Symmetric Crypto (MILP, SAT, etc.)
  • Selected Topics: Backdoors in Cryptography
  • Selected Topics: Password Hashing
  • Selected Topics: Secure Multi-Party Computation
  • Selected Topics: Homomorphic encryption
  • Selected Topics: Error correcting codes and cryptography

Lecturers

Maria Eichlseder
Maria
Eichlseder

Assistant Professor

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Christian Rechberger
Christian
Rechberger

Professor

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Daniel Kales
Daniel
Kales

PhD Student

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Markus Schofnegger
Markus
Schofnegger

PhD Student

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