Hartmut Koenig

A survey of video encryption algorithms

The popularity of multimedia applications is rapidly growing nowadays. The confidentiality of video communication is of primary concern for commercial usage, e.g. in video on demand services or business meetings. A variety of video encryption algorithms have been proposed in order to fulfill the specific requirements raised by the peculiarities of video communication. Video encryption algorithms can be classified according to their association with video compression into joint compression and encryption algorithms, and compression-independent encryption algorithms. From this classification perspective, we give a complete survey of the representative video encryption algorithms proposed so far and present their properties and limitations. We show by comparing and assessing the surveyed schemes that each scheme has its own strengths and weaknesses and no scheme can meet all specific requirements. Hence, video applications have to select an appropriate video encryption algorithm that meets their confidentiality requirements.

A novel encryption algorithm for high resolution video

The popularity of multimedia applications is rapidly growing nowadays. The confidentiality of video communication is of primary concern for their commercial use, e.g. in video on demand services or in multiparty video conferences. Specific video encryption algorithms are strongly required in real-time multimedia communication to fulfill the strict timing requi-rements. In this paper we present a novel video encryption algorithm, called Puzzle, to encrypt video data in software. It is fast enough to meet real-time demands and provides a sufficient security. The algorithm can readily be incorporated into existing multimedia systems.

Improving the efficiency of misuse detection

In addition to preventive mechanisms intrusion detection systems (IDS) are an important instrument to protect computer systems. Most IDSs used today realize the misuse detection approach. These systems analyze monitored events for occurrences of defined patterns (signatures), which indicate security violations. Up to now only little attention has been paid to the analysis efficiency of these systems. In particular for systems that are able to detect complex, multi-step attacks not much work towards performance optimizations has been done. This paper discusses analysis techniques of IDSs used today and introduces a couple of optimizing strategies, which exploit structural properties of signatures to increase the analyze efficiency. A prototypical implementation has been used to evaluate these strategies experimentally and to compare them with currently deployed misuse detection techniques. Measurements showed that significant performance improvements can be gained by using the proposed optimizing strategies. The effects of each optimization strategy on the analysis efficiency are discussed in detail.

Cryptanalysis of a SIP authentication scheme

SIP (Session Initiation Protocol) is becoming the mostly deployed signaling protocol for VoIP (Voice over IP). Security is of utmost importance for its usage due to the open architecture of the Internet. Recently, Yoon et al. proposed a SIP authentication scheme based on elliptic curve cryptography (ECC) that claimed to provide higher security than other schemes. However, as demonstrated in this paper, it is still vulnerable to off-line dictionary and partition attacks.

Location-independent fall detection with smartphone

Due to demographic changes in developed industrial countries and a better medical care system, the number of elderly people who still live in their home environment is rapidly growing because there they feel more comfortable and independent as in a clinical environment or in a residential care home. The elderly often live alone and receive only irregular visits. Due to impaired physical skills the probability of falls significantly increases. The detection of falls is a crucial aspect in the care of elderly. Falls are often detected very late with severe consequential damages. There are existing approaches for automatic fall detection. They usually deploy special external devices. Elderly people often do not accept these devices because they expose their frailty. In this paper, we present a location-independent fall detection method implemented as a smartphone application for an inconspicuous use in nearly every situation of the daily life. The difficulty of our approach is in the low resolution range of integrated acceleration sensors and the limited energy supply of the smartphone. As solution, we apply a modular threshold-based algorithm which uses the acceleration sensor with moderate energy consumption. Its fall detection rate is in the average of current relevant research.

Designing and Verifying Communication Protocols Using Model Driven Architecture and Spin Model Checker

The need of communication protocols in todaypsilas environment increases as much as the network explores. Many new kinds of protocols, e.g. for information sharing, security, etc., are being developed day-to-day which often leads to rapid, premature developments. Many protocols have not scaled to satisfy important properties like deadlock and livelock freedom, since MDA focuses on the rapid development rather than on the quality of the developed models. In order to fix the above, we introduce a 2-Phase strategy based on the UML state machine and sequence diagram to satisfy the properties of communication protocols. We convert these models into PROMELA code for execution on the SPIN model checker. The results are compared with the developed UML models.

Puzzle: a novel video encryption algorithm

Networked multimedia applications have matured in recent years to be deployed in a larger scale in the Internet. Confidentiality is one of the primary concerns of these services for their commercial usages, e.g. in video on de mand services or in video conferences. In particular, video encryption algorithms are strongly required that fulfill real-time requirements. In this paper we present the video encryption algorithm Puzzle to encrypting video streams in software. It is fast enough to fulfill real-time constraints and to provide a sufficient security. Puzzle is a video compression independent algorithm which can be easily incorporated into existing multimedia systems.

OCTOPUS-a scalable global multiparty video conferencing system

This paper reports a joint work between the Hong Kong University of Science and Technology and the Brandenburg Technical University of Cottbus, Germany, in developing a global video conferencing framework called OCTOPUS that interconnects local conferencing systems over long distances. The system makes use of both high level information provided by the participants (to decide which videos are more important to them) as well as low level adaptive mechanisms to perform media scaling as the network and the processor intensities change. It is possible to provide a customized service to each conference participant according to his/her needs and the resources available at each site. OCTOPUS itself makes no assumption on the architecture of the local video conference systems. The paper presents the architecture and the design philosophy of the OCTOPUS framework.

Consistency support for a decentralized management in close multiparty conferences using SIP

Distributed multimedia applications such as conference and collaborative applications require an appropriate conference management. Close group conferences like meetings, discussions, tele seminars, or consultations need a strictly controlled group membership. Current conference systems achieve this by using a centralized group server as specified in the H.32x standards. Decentralized approaches are scarcely used so far, although they are more flexible. They avoid infrastructure dependencies and single point of failure problems which are often encountered in group server approaches, e.g. in classical virtual private networks. A decentralized conference management requires a consistency support by the underlying communication service. The session initiation protocol (SIP) has become a widely applied protocol to support the signaling of multimedia applications in the Internet It is also applied to support multiparty conference applications. The great majority of these approaches is related to open group and centralized organized conferences. For closed decentralized managed conferences, no solutions have been proposed up to now. In this paper we present such a group communication service based on SIP that ensures the consistency of decentralized managed group data.

GCSVA-a multiparty videoconferencing system with distributed group and QoS management

In this paper, we introduce the multiparty videoconferencing system GCSVA (group communication and scalability in videoconferencing over ATM). It has been designed for the support of collaborative applications. The main features of GCSVA are: a strong floor control organization, dynamic scalability of video streams according to the number and the performance of the connected hosts, and a distributed group and QoS management. We describe these features as well as the design decisions made for their introduction. Finally, we give a short overview about the group communication protocol which constitutes the central element of the approach.