Activity Report 2003

Laboratory of Cryptography and System Security (CrySyS)
Department of Telecommunications
Budapest University of Technology and Economics

The laboratory has three types of activities: research, teaching, and maintaining industrial partnership. Following this classification, this report is divided into three parts.


In 2003, we continued two ongoing research projects on detecting and preventing network denial-of-service attacks, and on using smart cards at potentially untrusted terminals. In addition to these two projects, we started a new research activity on security in ubiquitous computing. In the following, we give a breif description of these projects, and a list of related papers that were published in 2003.

Detecting and preventing DoS attacks

Denial of Serice (DoS) attacks occupy a distinguished place among the most dangerous issues in Internet security. Although there are several ideas and solutions for some areas of this problem, in most cases, it is possible to carry out some type of DoS attack against existing internet systems. In this project, we are developing models for DoS attacks and some basic methods that could be used to prevent them. The main scientific questions that we want to answer are the following: (a) What are the possible boundaries of DoS protection methods? and (b) How much threat can be dealt with?

Researchers involved in this project: Boldizsár Bencsáth and Prof. István Vajda

Publications: BVB03softcom, BV04cts

Smart cards and untrusted terminals

Smart cards, having no user interface, are unable to communicate with the user directly. Communication is only possible with the aid of a terminal, which leads to several security problems. For example, the terminal may perform a man-in-the middle attack. Although the problem is widespread, it has relatively little literature. We have developed a solution which can alleviate the problem. It is based on a new concept called conditional signatures. We are currently implementing a prototype of our proposal and extending it with privacy protecting mechanisms.

Researchers involved in this project: István Zsolt Berta, Prof. Levente Buttyán, and Prof. István Vajda

Publications: BBV04itcc, BB03et1, BB03et2

Security for Ubiquitous Computing

The vision of ubiquitous computing is to surround people with all kinds of embedded computing devices that could assist them in their everyday activity and make their life easier. Providing security in a ubiquitous computing environment can be very challenging for several reasons, including the following:

In this project we are working on the following specific topics: We obtained support for this project for 4 years (2004--2007) from the Hungarian Scientific Research Fund (OTKA in Hungarian).

Researchers involved in this project: Prof. Levente Buttyán, Prof. István Vajda, and Attila Bognár
Note 1: Some parts of this project have been carried out in collaboration with the group of Prof. Jean-Pierre Hubaux at the Swiss Federal Institute of Technology -- Lasuanne (EPFL)
Note 2: We intend to recruit at least two new PhD students for this project in the near future.

Publications: BH03monet, CBH03ieeetmc, BH02mc2r, CBH03sasn, VB03suc, FBH03pwc, CHB03mobihoc, BBHJ03mobihoc, JHB03fc, FHB04wiopt

Publications in 2003

Journal and magazine papers:
[BB03et1]  I. Zs. Berta, I. Berta,
Hardware and Software Security I,
Elektrotechnika, vol 2003/10, 2003.

[BB03et2]  I. Zs. Berta, I. Berta,
Hardware and Software Security II,
Elektrotechnika, vol 2003/11, 2003.

[BH03monet]  L. Buttyán and J.-P. Hubaux,
Stimulating Cooperation in Self-Organizing Mobile Ad Hoc Networks,
ACM/Kluwer Mobile Networks and Applications (MONET), Vol. 8 No. 5, October 2003.

[CBH03ieeetmc]  S. Capkun, L. Buttyán, and J.-P. Hubaux,
Self-Organized Public-Key Management for Mobile Ad Hoc Networks,
IEEE Transactions on Mobile Computing, Vol. 2 No. 1, January-March 2003.

[BH02mc2r]  L. Buttyán and J.-P. Hubaux (eds.),
Report on a Working Session on Security in Wireless Ad Hoc Networks,
ACM Mobile Computing and Communications Review (MC2R), Vol. 7 No. 1, March 2003.

[GBK03ieeeds]  F. Gärtner, L. Buttyán, K. Kursawe,
From Fault-Tolerance to Security and Back,
IEEE Distributed Systems Online, Vol. 4, No. 9, 2003.

Conference and workshop papers:
[CBH03sasn]  S. Capkun, L. Buttyán, and J.-P. Hubaux,
SECTOR: Secure Tracking of Node Encounters in Multi-hop Wireless Networks,
ACM Workshop on Security in Ad Hoc and Sensor Networks (SASN 2003)
Fairfax, VA, USA, October 31, 2003.

[VB03suc]  I. Vajda and L. Buttyán,
Lightweight Authentication Protocols for Low-Cost RFID Tags,
2nd Workshop on Security in Ubiquitous Computing, in conjunction with Ubicomp 2003,
Seattle, Washington, USA, October 12, 2003.

[BVB03softcom]  B. Bencsáth, I. Vajda, and L. Buttyán,
A Game Based Analysis of the Client Puzzle Approach to Defend Against DoS Attacks,
IEEE Conference on Software, Telecommunications and Computer Networks (SoftCom 2003),
Split, Dubrovnik, Ancona, Venice, 7-10 October, 2003.

[FBH03pwc]  M. Félegyházi, L. Buttyán, and J.-P. Hubaux,
Equilibrium Analysis of Packet Forwarding Strategies in Wireless Ad Hoc Networks -- the Static Case,
8th International Conference on Personal Wireless Communications (PWC 2003),
Venice, Italy, 23-25 September, 2003.

[CHB03mobihoc]  S. Capkun, J.-P. Hubaux, and L. Buttyán,
Mobility Helps Security in Ad Hoc Networks,
4th ACM Symposium on Mobile Ad Hoc Networking and Computing (MobiHOC 2003),
Annapolis, Maryland, USA, 1-3 June, 2003.

[BBHJ03mobihoc]  N. Ben Salem, L. Buttyán, J.-P. Hubaux, and M. Jakobsson
A Charging and Rewarding Scheme for Packet Forwarding in Multi-hop Cellular Networks,
4th ACM Symposium on Mobile Ad Hoc Networking and Computing (MobiHOC 2003),
Annapolis, Maryland, USA, 1-3 June, 2003.

[JHB03fc]  M. Jakobsson, J.-P. Hubaux, and L. Buttyán,
A Micro-Payment Scheme Encouraging Collaboration in Multi-Hop Cellular Networks,
7th International Financial Cryptography Conference (FC),
Gosier, Guadeloupe, FWI, January 27-30, 2003.

Accepted papers (to be published in 2004):
[BHC03jcs]  L. Buttyán, J.-P. Hubaux, and S. Capkun,
A Formal Model of Rational Exchange and its Application to the Analysis of Syverson's Protocol,
to appear in the Journal on Computer Security, special issue of selected papers from CSFW 15

[BBV04itcc]  I. Berta, L. Buttyán, and I. Vajda
Mitigating the Untrusted Terminal Problem Using Conditional Signatures,
International IEEE Conference on Information Technology (ITCC 2004)
Las Vegas, NV, USA, April 5-7, 2004.

[FHB04wiopt]  M. Félegyházi, J.-P. Hubaux, and L. Buttyán,
Equilibrium Analysis of Packet Forwarding Strategies in Wireless Ad Hoc Networks -- the Dynamic Case,
2nd Workshop on Modeling and Optimization in Mobile, Ad Hoc and Wireless Networks (WiOpt 2004)
Cambridge, UK, March 24-26, 2004.

[BV04cts]  B. Bencsáth, I. Vajda,
Protection Against DDoS Attacks Based On Traffic Level Measurements,
International Symposium on Collaborative Technologies and Systems,
San Diego, CA, USA, January 2004.


New Special on Security in Information and Communication Systems

The lab played an important role in the setup of the new Special on Security in Information and Communication Systems that CS students can choose in the 7th semester of their curriculum. The special consists of 5 courses and 18 laboratory exercises. In addition, many of the students usually do their 3 semester and 1 diploma projects on a topic that is related to the chosen special.

During spring and summer 2003, our lab coordinated the establishment of the special, had a leading role in the definition of the curriculum, and specifically worked out 1 course (Network Security Protocols) and two laboratory exercises. Another course (Foundations of Secure Electronic Commerce) and 3 more laboratory exercises will be worked out in 2004.


Boldizsár Bencsáth, István Zsolt Berta, and Attila Bognár provided help in the correction of the tests and exams during the whole year.

Laboratory exercises

The exercises were developed by Boldizsár Bencsáth with the help of István Zsolt Berta and Attila Bognár. The exercise sessions were supervised by Boldizsár Bencsáth and István Zsolt Berta.

Student semester projects

Projects supervised by Prof. Levente Buttyán:

A book

Prof. István Vajda and Prof. Levente Buttyán completed a book that is entilted Cryptography and Its Applications (in Hungarian), which will be published in 2004 by TypoTeX.

Industrial partnership

The lab participated in a government funded project where we wrote a technical report on how to increase the efficiency of today's anti-virus tools.

Miscellaneous notes

The laboratory was formerly known as Ebiz Lab. The laboratory has been called CrySyS Lab since January 2003.

There were some changes in the set of members of the lab: Prof. Levente Buttyán joined the lab in January 2003. István Verók left the lab in the summer of 2003.

buttyan (at)