Cryptography

This course is listed

• in Aachen RWTHonline as Cryptography,
• in Bonn Basis as MA-INF 1103 - Cryptography.
• in eCampus as * MA-INF 1103 - Cryptography. (+sign-up),

Cryptography deals with methods for secure data transfer. In earlier times this was the domain of military and intelligence agencies, but today modern cryptography has grown into a key technology, enabling e-commerce and secure internet communications. Its many applications range from credit and debit cards, mobile phones, tv decoders, and electronic money to unforgeable electronic signatures under orders and contracts in the internet.

In the course, we discuss two of the current standard tools, namely AES and RSA. Further topics are key exchange, including group cryptography and discrete logarithm, digital signatures and identification, and cryptographic hash functions. We will consider these primitives in the modern light of reducible security (or provable security).

Michael Nüsken

Notice: This course is given in a flipped classroom format.

• Plenum: Wednesday, 12⁰⁰ c.t.-14⁰⁰, b-it  2.113 and digital lecture room. (Room was b-it 0.107 before 2025-11-07.)
  Discussions of questions and items related to exercises, lectures and everything.
• Tutorial: Monday 12⁰⁰ c.t.-14⁰⁰, b-it 0.107 and digital tutorial room.
  Guided help for present exercises and topics.
  Presentations of just reviewed solutions.
• Consultation time (optional): Monday, 14⁰⁰ c.t.-16⁰⁰, digital lecture room.
  This is for personal questions.

First meeting:

• Monday, 27 October 2025, 12⁰⁰ c.t.-16⁰⁰, Introduction & Speed grouping, b-it -max 0.107 and digital lecture room.

You will find notes and exercises at sciebo until September 2026.

Lecture recordings, exercise handin and feedback are handled via the eCampus pages of the course.

It is strongly suggested to prepare a crib sheet: one A4 sheet, both sides, handwritten by yourself, with the -in your eyes- most important things about the course. This is also allowed during the exam.

Pre-exam meeting: Wednesday, 4 February 2026, in/after the plenum.

Exam1: Tuesday, 17 February 2026, 13⁰⁰-16⁰⁰, b-it-max 0.109.

Exam1 review: Wednesday, 25 February 2026, 11⁰⁰-12³⁰, tba.

Exam2 (repetitions): Wednesday, 31 March 2026, 13⁰⁰-16⁰⁰, b-it-max 0.109.

Exam2 review: tba.

• Jonathan Katz & Yehuda Lindell (2015/2008). Introduction to Modern Cryptography, CRC Press. Webpage.
• Mike Rosulek (2017+). The Joy of Cryptography. Webpage including PDF.
• Boaz Barak (2019+). An Intensive Introduction to Cryptography. Webpage.
   
• Mihir Bellare & Shafi Goldwasser (2001). Lecture Notes on Cryptography. PDF.
• Dan Boneh & Victor Shoup (2017). A Graduate Course in Applied Cryptography.
• Johannes A. Buchmann (2004). Introduction to Cryptography. Birkhäuser Verlag, 2nd edition. ISBN 0-387-21156-X (hardcover), 0-387-20756-2.
• Joachim von zur Gathen (2015). CryptoSchool. Springer. ISBN 978-3-662-48425-8.
• Nigel Smart (2002), Cryptography: An Introduction. McGraw-Hill. ISBN 0-077-09987-7. This first edition is out of print, but a new edition is available online (PDF).
• Nigel Smart (2015). Cryptography Made Simple. Springer, ISBN 978-3-319-04041-7. Webpage including PDF. Errata.
• Howard M. Heys (2001). A Tutorial on Linear and Differential Cryptanalysis. Technical Report CORR 2001-17, Centre for Applied Cryptographic Research, Department of Combinatorics and Optimization, University of Waterloo, Mar. 2001. (Also appeared in Cryptologia, vol. XXVI, no. 3, pp. 189-221, 2002.) PDF on author's webpage.
• Douglas R. Stinson (2005). Cryptography - Theory and Practice. Discrete Mathematics and its Applications. Chapman & Hall / CRC Press, Boca Raton FL, 3rd edition. ISBN 1584885084, 600pp.

There is a long list of free online books about cryptography.

Further topics:

• James S. Kraft & Lawrence C. Washington (2014). An introduction to Number Theory with Cryptography.
• Steven Galbraith (2018). Mathematics of Public Key Cryptography. Webpage including PDF.

• ... for the course: None.
• .. for participating in the exam: Present twice in the tutorial.

4+2 SWS.

• Master in Media Informatics: Computer and Communication Technology, 8 ECTS credits.
• Master in Computer Science at University of Bonn: MA-INF 1103, 9 CP.