60446
EPspectra: a formal toolkit for developing DSP software applications
The software approach to developing Digital Signal Processing (DSP) applications brings some great features such as flexibility, re-usability of resources and easy upgrading of applications. However, it requires long and tedious tests and verification phases because of the increasing complexity of the software applications. This implies the need of a software programming environment capable of putting together DSP modules and providing facilities to debug, verify and validate the code. The objective of the work is to provide such facilities as simulation and verification for developing DSP software applications. This led us to developing an extension toolkit, EPSPECTRA, built upon PSPECTRA, one of the first toolkits available to design basic software radio applications on standard PC workstations. In this paper, we first present EPSPECTRA, an ESTEREL-based extension of PSPECTRA that makes the design and implementation of portable DSP applications easier. It allows the drastic reduction of testing and verification time while requiring relatively little expertise in formal verification methods. Second, we demonstrate the use of EPSPECTRA, taking as an example the radio interface part of a GSM base station. We also present the verification procedures for the three safety properties of the implementation programs which have complex control-paths. These have to obey strict scheduling rules. In addition, EPSPECTRA achieves the verification of the targeted application since the same model is used for the executable code generation and for the formal verification.
15684093
Efficient Authentication and Authorization of Mobile Users Based on Peer-to-Peer Network Mechanisms
This paper presents a peer-to-peer based authentication and authorization infrastructure to minimize authentication delays when mobile users roam across different wireless networks. The basic idea is to avoid exchanging security information between networks visited by a roaming user and the user's home authentication, authorization, and accounting (AAA) server that is typically located in the home network possibly far away from the visited network. Instead, authentication and authorization of a roaming user shall be supported by an AAA server in the visited network. We propose that the AAA server that is responsible for authentication and authorization in a newly visited network locates the AAA server in the previously visited network and retrieves the required security information from that AAA server. The AAA servers can be organized in a peer-to-peer manner and peer-to-peer mechanisms can be applied for searching and transferring security information between them. We propose several mechanisms for quickly locating the previously responsible AAA server in order to decrease authentication delays. The performance of these mechanisms is evaluated by simulations. Real performance measurements show the rather low performance overhead of application level forwarding used in peer-to-peer networks.
15273022
Open Location-Based Service Using Secure Middleware Infrastructure in Web Services
Location-based services or LBS refers to value-added service by processing information utilizing mobile user location. For this kind of LBS, the role of security service is very important in the LBS that store and manage the location information of mobile devices and support various application services using those location information. And in all phases of these functions that include acquisition of location information, storage and management of location information, user management including authentication and information security, and management of the large-capacity location information database, safe security service must be provided. We show the security methods for open LBS in this paper.
2255453
TCP offload through connection handoff
This paper presents a connection handoff interface between the operating system and the network interface. Using this interface, the operating system can offload a subset of TCP connections in the system to the network interface, while the remaining connections are processed on the host CPU. Offloading can reduce computation and memory bandwidth requirements for packet processing on the host CPU. However, full TCP offloading may degrade system performance because finite processing and memory resources on the network interface limit the amount of packet processing and the number of connections. Using handoff, the operating system controls the number of offloaded connections in order to fully utilize the network interface without overloading it. Handoff is transparent to the application, and the operating system may choose to offload connections to the network interface or reclaim them from the interface at any time. A prototype system based on the modified FreeBSD operating system shows that handoff reduces the number of instructions and cache misses on the host CPU. As a result, the number of CPU cycles spent processing each packet decreases by 16--84%. Simulation results show handoff can improve web server throughput (SEPCweb99) by 15%, despite short-lived connections.
35762748
Improved SQUARE Attacks against Reduced-Round HIEROCRYPT
We present improved SQUARE attacks against the NESSIE and ECTP candidate block ciphers HIEROCRYPT-3 and HIEROCRYPT-L1, designed by Toshiba. We improve over the previous best known attack on five S-box layers of HIEROCRYPT-3 by a factor of 2 128 computational steps with an attack on six layers for 128-bit keys, and extend it to seven S-box layers for longer keys. For HIEROCRYPT-L1 we are able to improve previous attacks up to seven S-box layers (out of twelve).
17995343
Automatic design of nonlinear filters by nearest neighbor learning
Nonlinear filters have been used not only in noise elimination but in a wide variety of image processing applications. Traditionally the design of a digital filter is a manual task and the user accomplishes it based on previous experiences. Unfortunately often this is not a trivial task. Thus some works try to overcome this difficulty constructing the filters automatically by computational learning neural networks, genetic algorithms and statistical estimation. These works use typical input-output images of the application as the training samples. Many different kinds of filters can be easily constructed using this approach. This paper proposes the use of nearest neighbor (NN) learning to automatic filter construction. The kd-tree (k-dimensional binary tree) is used to accelerate the NN searching. A texture recognition application example is depicted.
4378334
Semantics and implementation of schema evolution in object-oriented databases
Object-oriented programming is well-suited to such data-intensive application domains as CAD/CAM, AI, and OIS (office information systems) with multimedia documents. At MCC we have built a prototype object-oriented database system, called ORION. It adds persistence and sharability to objects created and manipulated in applications implemented in an object-oriented programming environment. One of the important requirements of these applications is schema evolution, that is, the ability to dynamically make a wide variety of changes to the database schema. In this paper, following a brief review of the object-oriented data model that we support in ORION, we establish a framework for supporting schema evolution, define the semantics of schema evolution, and discuss its implementation.