Tobias Martin

Tree-Based Multicast Key Agreement

We present an analysis of a multicast key agreement scheme based on the iterated Diffie-Hellman key agreement protocol and binary trees. This scheme is extremely efficient for deleting single members from the group and joining of groups. It does not need a group moderator, and is self-synchronizing.

On the Security of the UMTS System

This contribution presents an overview of the security of the 3rd generation mobile radio system UMTS as currently standardised by the 3rd Generation Partnership Project 3GPP. We discuss the underlying principles and show to which extent the security of 2nd generation systems as GSM is improved and enhanced by UMTS. The UMTS Authentication and Key Agreement protocol, the security algorithms deployed for UMTS and the interworking mechanisms between 2nd and 3rd generation systems are described in detail.

Practical experiences with purenet, a self-learning malware prevention system

This paper introduces Purenet, which is a self-learning malware detection system aimed at avoiding zero-day attacks and other delays in patching application systems when attacks are identified. The concept and architecture of Purenet are described, specifically positioning anomaly detection as the system enabler. Deployment of the system in an operational environment is discussed, and associated recommendations and findings are presented based on this. Findings from the prototype include various considerations which should influence the design of such security software including latency considerations, multi protocol support, cloud anti-malware integration, resource requirement issues, reporting, base platform hardening and SIEM integration.

From pay-tv to pay-streaming: similarities and differences

In this paper, we want to point out similarities and differences between digital Pay-TV, which uses MPEG-2 transport streams, and its future analogue for IP based services, which we call Pay-Streaming. After an introduction to encryption, re-keying and key management in the European DVB model for Pay-TV, we consider existing (IPSec, IP multicast) and missing (key management) building blocks for Pay-Streaming in the Internet. We conclude with a discussion of some practical aspects related to the standard PC architecture.

Schlüsselvereinbarung für IP Multicast mit modifiziertem SSL/TLS

Das Secure Socket Layer-Protokoll (SSL) dient zur Absicherung jeweils einer Client-Server-Verbindung im Internet. Durch die Art und Weise der Ableitung der Sitzungsschlussel ist SSL nicht fur andere Verbindungstopologien (z.B. Punkt-zu-Multipunkt) geeignet. Die IP Multicast Technologie stellt (fur bestimmte Anwendungen hocheffiziente) Punkt-zu-Multipunkt-Ubertragungswege bereit. Wir stellen ein modifiziertes SSL/TLS-Handshake-Protokoll vor, mit dem Sitzungsschlussel fur solche Verbindungen vereinbart werden konnen.