Now showing 1 - 10 of 80
  • Publication
    JASMINE: A Java tool for multimedia collaboration on the internet
    ( 2003)
    Shirmohammadi, S.
    ;
    Saddik, A. el
    ;
    Georganas, N.D.
    ;
    Steinmetz, R.
    Although collaboration tools have existed for a long time [8], Internet-based multimedia collaboration has recently received a lot of attention mainly due to easy accessibility of the Internet by ordinary users. The Java platform and programming language has also introduced yet another level of easy access: platform-independent computing. As a result, it is very attractive to use Java to design multimedia collaboration systems for the Internet. Today there are many systems, which use Java for multimedia collaboration. However, most of these systems require the shared Java application to be re-written according to the collaboration system's Application Programming Interface (API)-a task which is sometimes difficult or even impossible. In this paper, we describe a practical approach for transparent collaboration with Java. Our approach is transparent in that the Java application can be shared as is with no modifications. The main idea behind our system is that user events occurring through the interactions with the application can be caught, distributed, and reconstructed, hence allowing Java applications to be shared transparently. Our architecture allows us to make the huge installed base of Java applications collaborative, without any modification to their original code. We also prove the feasibility of our architecture by implementation of the JASMINE 1 prototype.
  • Publication
    Biometric hash based on statistical features of online signatures
    ( 2002)
    Vielhauer, C.
    ;
    Steinmetz, R.
    ;
    Mayerhöfer, A.
    This paper presents a new approach to generate biometric hash values based on statistical features in online signature signals. Whilst the output of typical online signature verification systems are threshold-based true-false decisions, based on a comparison between test sample signals and sets of reference signals, our system responds to a signature input with a biometric hash vector, which is calculated based on an individual interval matrix. Especially for applications, which require key management strategies (e.g. e-Commerce, smart cards), hash values are of great interest, as keys can be derived directly from the hash value, whereas a verification decision can only grant or refuse access to a stored key. Further, our new approach does not require storage of templates for reference signatures, thus increases the security of the system. In our prototype implementation, the generated biometric hash values are calculated on a pen-based PDA and used for key generation f or a future secure data communication between a PDA and a server by encryption. First tests show that the system is actually able to generate stable biometric hash values of the users and although the system was exposed to skilled forgeries, no test person was able to reproduce another subject's hash vector. During tests, we were able to tune the system to a FAR of 0% at a FRR level of 7.05%.
  • Publication
    VC management for heterogeneous QoS multicast transmissions
    ( 2002)
    Schmitt, J.
    ;
    Wolf, L.
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    Karsten, M.
    ;
    Steinmetz, R.
    A crucial component of the interaction between ATM's and the Internet's Quality of Service (QoS) architectures is the efficient mapping of RSVP (Resource reSerVation Protocol) as the Internet's signalling protocol onto the according ATM mechanisms. In particular, this article focuses on one of the most contrary characteristics of RSVP and ATM signalling. This is the support for heterogeneous reservations by RSVP over the ATM subnetwork, taking into account that ATM only allows for a homogeneous QoS within a single Virtual Circuit (VC). We present previous approaches to the solution of this problem and argue for more sophisticated and efficient approaches to manage ATM VCs taking into consideration ATM tariffs and resource consumption.
  • Publication
    Verfahren zur Diensteerkennung und Diensteinformationsbereitstellung im Vergleich
    ( 2002)
    Kirchner, H.
    ;
    Schönfeld, W.
    ;
    Steinmetz, R.
  • Publication
    Modeling IP-based mobility management
    ( 2002)
    Schönfeld, W.
    ;
    Meissner, A.
    ;
    Kirchner, H.
    ;
    Steinmetz, R.
  • Publication
    Verfahren zur Diensteerkennung und Diensteinformationsbereitstellung im Vergleich
    ( 2002)
    Kirchner, H.
    ;
    Schönfeld, W.
    ;
    Steinmetz, R.
  • Publication
    Biometric authentication for ID cards with hologram watermarks
    ( 2002)
    Croce Ferri, L.
    ;
    Mayerhöfer, A.
    ;
    Frank, M.
    ;
    Vielhauer, C.
    ;
    Steinmetz, R.
  • Publication
    Vulnerabilities and security limitations of current IP telephony systems
    ( 2001)
    Ackermann, R.
    ;
    Schumacher, M.
    ;
    Roedig, U.
    ;
    Steinmetz, R.
    Within the traditional telephone system a certain level of quality and security has been established over the years. If we try to use IP Telephony systems as a core part of our future communication infrastructure (e.g. as classical PBX enhancement or replacement) continuous high availability, stable and error-free operation and the protection of the privacy of the spoken word are challenges, that definitely have to be met. Since manufacturers start deploying new end systems and infrastructure components rather fast now - a critical inspection of their security features and vulnerabilities is mandatory. The critical presentation of the theoretical background of certain vulnerabilities, testing and attacking tools and the evaluation results reveals, that well-known security flaws become part of implementations in the new application area again and the security level of a number of examined solutions is rather insufficient.
  • Publication