Bonn-Aachen International Center
for Information Technology





city life
cosec >students >Teaching >Summer 2015 

Esecurity: secure internet & e-cash

This course is listed in Aachen Campus as Esecurity: secure internet & e-cash and in Bonn Basis as Esecurity: secure internet & e-cash oder MA-INF 3222 - Esecurity: secure internet & e-cash.


Prof. Dr. Joachim von zur Gathen


Michael Nüsken


Michael Nüsken

Time & Place

First meeting: Tuesday, 07 April 2015.

All times subject to agreement in class.


Pre-exam meeting: probably Tuesday, 8 September 2015, 1000, b-it 1.25 (cosec meeting room).

Exam: Monday, 14 September 2015, 1000, b-it 0.4.

Post-exam meeting: Monday, 19 October 2015, 1400, b-it 1.25 (cosec meeting room).

Exam2 (repetitions only): Wednesday, 18 November 2015, 1400, b-it 1.25 (cosec meeting room).

Post-exam meeting: Thursday, 14 January 2016, 1430, b-it 1.25 (cosec meeting room).


The screen notes (PDF 32.4MB) contain all handwritten stuff (last updated 17 July 2015, 17:46).




4+2 SWS.


Basic knowledge in cryptography is needed, as for example the course Cryptography held in the previous winter. Compare our programme.


This course is about various aspects of security in the internet. In the first part we deal with secure connections, whereas the second part considers electronic voting schemes involving further tasks.

In the internet a large variety of protocols ("chatting programs") are in use to make this or that `secure'. VPN, IPsec, SSL, PKI, PGP are just a few tokens that need explanations. We will try to understand a little of that and how things are used and made available.

The application issue this year deals with electronic cash. There are a variety of proposals about how to realize a counter part to real coins (cash!) in the internet. However, most of the approaches that are used in practive are account based. But then transactions are not anonymous. What we are heading for in this chapter are systems that are as anonymous as real coins are. In particular, they must be account free since otherwise the account manager sees all transactions. Thus a certain bit string may be a valid coin. The problem with bit strings as compared to real coins is: they are fairly easy to copy. But one should not be able to just duplicate coins because that would render that kind of coin worthless. There are solutions to this double spending problem. Further issues then arise: real coins can be transferred many times from owner to owner, in case of extortion we may want a tracing option, ...


We will put each member on the mailing list

[Sorry, you need to enable Javascript to see this.]
. You can also subscribe yourself. The list is intented for all participants of the course as a platform for discussions around the topic. Furthermore, announcements regarding the course are made here.

Imprint, webmaster & more