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
    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
    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
    Transitivity based enrollment strategy for signature verification systems
    ( 2001)
    Vielhauer, C.
    ;
    Steinmetz, R.
    ;
    Mayerhöfer, A.
  • Publication
    On the aggregation of deterministic service flows
    ( 2001)
    Schmitt, J.
    ;
    Karsten, M.
    ;
    Steinmetz, R.
    It is common belief that "flat" Quality of Service (QoS) architectures, e.g. the IETFs Integrated Services architecture (IntServ), are not scalable to large networks, e.g. the global Internet. This is due to the ambitious goal of providing per-flow QoS and the resulting complexity of fine-grained traffic management. One solution to this problem is the aggregation of traffic flows in the core of the network, thus creating a hierarchical resource allocation system. While one might suspect that aggregation leads to allocating more resources for the aggregated flow than for the sum of the separated flows if flow isolation shall be guaranteed deterministically, we show in this article that for IntServ's Guaranteed Service flows this is not necessarily the case even if flow isolation is retained. We compare different approaches to describe the aggregated traffic and analyze their impact on bandwidth consumption and ease of flow management. Furthermore, we perform a thorough numerical evaluation of the derived results with respect to their behavior in response to changes in exogenous parameters like the traffic specifications of the flows or the configuration of the network. Applications of these theoretical insights and numerical evidence could be to use the derived formulae for resource allocation in either a hierarchical IntServ, IntServ over DiffServ (Differentiated Services), or IntServ over ATM (Asynchronous Transfer Mode) network.