Overview

  • Lecturer: Dominique Unruh
  • Semester: Winter 2026/27
  • Level: Bachelor / Master
  • Time/Room: TODO
    (Not every time, see the “important information” in Moodle for details.)
  • Further links: RWTHonline view, Moodle Room TBA
  • Exam: TBA

Description

Cryptography is the science of processing data in the presence of an adversary. It encompasses encryption and signatures, but many other things, too. In this lecture, we will explore the most important concepts of modern cryptography, learn what security means (mathematically), how to prove it, and how to construct cryptographic schemes.

The lecture targets the theoretical foundations, not the practical implementation of deployment-ready cryptographic schemes. However, a good understanding of the former is necessary to understand the latter, too.

Materials

Most materials and information are in the Moodle room.

Content

The module covers the following topics:

  • Foundations: security goals, attack models, and the game-based security framework
  • Pseudorandomness: one-way functions, pseudorandom generators, and pseudorandom functions
  • Symmetric cryptography: secret-key encryption, CPA and CCA security, message authentication codes, authenticated encryption
  • Hash functions: collision resistance, the random oracle model
  • Public-key cryptography: key encapsulation, public-key encryption (IND-CPA, IND-CCA), digital signatures
  • Hardness assumptions: discrete logarithm, RSA, Diffie-Hellman, and related problems; introduction to lattice-based assumptions
  • Security proofs: reduction-based arguments, hybrid proofs, and standard proof techniques

In addition, the module covers selected advanced topics, which may vary by semester. Possible topics include zero-knowledge proofs, post-quantum cryptography, identity-based encryption, secure computation, or cryptographic applications in decentralized systems.

Guests

Non-RWTH-members who wish to take this course must be registered via the proper channels (as a “Zweithörer” or “Gasthörer”). However, if you wish to follow the course in an inofficial capacity (i.e., access the course materials, etc.) contact me, and I invite you to the Moodle room. (Note: inofficial participation does not include any supervision, exams, or other things that require personnel resources on our side.)