Teaching Applied Cryptography

Lectures Applied Cryptography

Summer semester 2020

Lecture: 20-00-1051-vl Provable Security

Teaching content:

This lecture shows how to formally prove security guarantees of cryptographic protocols. We focus on strong security guarantees and realistic adversary models. We use several different proving techniques. We will apply our knowledge to encryption schemes, some of which are used in practice, to gain a better understanding of their security properties.

  • Introduction to provable security
    • Definition of security
    • Introduction to computation security
    • Concept of a reduction
    • Cryptographic assumptions (OWF, factoring, discrete log, etc.)
    • Introduction to information theory
  • Symmetric encryption
    • Information theoretic secure encryption
    • Computationally secure encryption
    • OWF implies PRG
    • PRG implies encryption
  • Asymmetric encryption
    • IND-CPA security and ElGamal encryption
    • Proof of security of ElGamal
    • Naor/Yung scheme
    • Cramer/Shoup scheme
  • Extended security properties of encryption
    • Leakage resilient encryption
    • Random oracle model
    • Simulation-based security
    • Universal Composability Framework

Requirements: “Introduction to Cryptography” is recommanded but not mandatory.

Seminar: 20-00-1088-se Side-channel resilient cryptography

Teaching content:

Cryptographic schemes are classically secure against black-box attacks, where an attacker exploits weaknesses of the underlying cryptographic algorithm. When cryptography is implemented in practice, so-called side-channel attacks are a further threat to their security. Most of cryptography can be broken by side-channel attacks and countless examples illustrate that almost all the devices that are in use today are affected by them. Starting in the late 1990s, when Kocher showed that smart cards can be broken using timing or power analysis attacks, there has been a plethora of different side-channel attacks been discovered. Most recently, examples such as Foreshadow illustrate that even advanced computing machinery is vulnerable to side-channel attacks.

Leakage resilient cryptography is the discipline that formalises these practical attacks in order to use formal methods for demonstrating security against them. In particular, it defines new security models, so-called leakage models, that incorporate side-channel attacks into the classical security models, and design cryptographic schemes that are provable secure within them.

Requisites: The seminar is aimed at master students. Basic lecture IT security or basic knowledge in cryptography are recommended, but not mandatory.

Practicum: 20-001031-pr Blockchain Practicum

Teaching content:

This course is aimed at students who have attended the lecture Cryptocurrencies and want to understand and examine some aspects of this topic in more detail. It provides a platform to check novel applications based on Blockchain technology for their feasibility and usefulness.

Complex cryptographic systems and ideas from the lecture Cryptocurrencies should be understood in team work and implemented in a decentralized system. The students are asked to develop a project plan and outline, which should be implemented over the course of the semester.

The students get first experiences with the implementation of a more complex development project.

Requirements: This course is directed at students that finished the cryptocurrencies lecture with good marks and programming skills.

Winter semester 2019/2020

Summer semester 2019

Winter semester 2018/2019

Summer semester 2018

Winter semester 2017/2018