3206603
BGN Authentication and Its Extension to Convey Message Commitments
We instantiate the cryptosystem proposed by Boneh, Goh, and Nissim in TCC'05 [5] into an entity authentication scheme, in which an entity is authenticated by an interactive zero-knowledge proof on its private key. Completeness and soundness of our scheme is supported by the indistinguishability of BGN ciphertexts of sums and products, which essentially relies on the semantic security of the BGN cryptosystem. We further extend our scheme so that the authentication conveys Pedersen commitments on a message, while the BGN authentication serves the ‘proving you know how to open' functionality for the commitment. Our message commitment scheme is both statistically hiding and computationally binding provided the subgroup decision problem is hard.
28992997
Creating reusable WebQuest objects with WebQuest authoring engine
WebQuest is a constructivist lesson format for Web-enabled inquiry-based learning. A WebQuest exists in form of a Web site that contains a collection of Web pages. In this paper, we define the "WebQuest Object" which is basically a learning object. We also present the WebQuest authoring engine which enables one to generate WebQuest objects without the knowledge in Web page construction and publishing. The WebQuest authoring engine also allows ones to edit the metadata of the WebQuest so as to facilitate the reuse of the WebQuest objects.
10812167
A TCP-Friendly Stateless AQM Scheme for Fair Bandwidth Allocation
Queue management, bandwidth share, and congestion control are very important to both robustness and fairness of the Internet. In this article, we investigate the problem of providing a fair bandwidth allocation to those flows that share congested link in a router. A new TCP-friendly router-based AQM (active queue management) scheme, termed WARD, is proposed to approximate the fair queueing policy. WARD is a simple packet dropping algorithm with a random mechanism, and discriminates against the flows which transmit more packets than allowed. By doing this, it not only protects TCP connections from UDP flows, but also solves the problem of competing bandwidth among different TCP versions such as TCP Vegas and Reno. In addition, WARD works quite well for TCP flow isolation even with different round trip times. In other words, WARD improves the unfair bandwidth allocation properties. Furthermore, it is stateless and easy to implement, so WARD controls unresponsive or misbehaving flows with a minimum overhead
841469
Variable temporal-length 3-D discrete cosine transform coding
Three-dimensional discrete cosine transform (3-D DCT) coding has the advantage of reducing the interframe redundancy among a number of consecutive frames, while the motion compensation technique can only reduce the redundancy of at most two frames. However, the performance of the 3-D DCT coding will be degraded for complex scenes with a greater amount of motion. This paper presents a 3-D DCT coding with a variable temporal length that is determined by the scene change detector. Our idea is to let the motion activity in each block be very low, while the efficiency of the 3-D DCT coding could be increased. Experimental results show that this technique is indeed very efficient. The present approach has substantial improvement over the conventional fixed-length 3-D DCT coding and is also better than that of the Moving Picture Expert Group (MPEG) coding.
894881
Performance improvement of TCP Vegas over heterogeneous networks
Current IP network has become the dominant paradigm for all networking environments. The significant cause of packet losses in such heterogenous networks is no longer limited to network congestion. Traditional TCP interprets every packet loss as caused by congestion which may be not the case in the current Internet. Misinterpretation of wireless random loss as an indication of network congestion results in TCP slowing down its sending rate unnecessarily. We propose a new variant of TCP Vegas named RedVegas. By using the innate nature of Vegas and congestion indications marked by routers, RedVegas may detect random packet losses precisely. Through the packet loss differentiation, RedVegas reacts appropriately to the losses, and therefore the throughput of connection over heterogeneous networks can be significantly improved.
31127718
Detecting a Security Disturbance in Multi Commodity Stochastic Networks
Here is a multi-criteria approach to identify and evaluate network-flow monitoring strategies in a stochastic environment. We propose an analytical approach for assessing flow disturbance, based on limited sampling of arc-flow information in multi commodity, or multiple origin-destination (O–D), networks. A disturbance is defined here as abnormal network traffic beyond routine fluctuations. The network is characterized by arcs that are available with certain probabilities, suggesting a busy packet-switching/circuit-switching network, or simply network with failing components. Given the huge state space of such stochastic networks, our first objective is to bound the expected flow for computational efficiency. This is accomplished by extending available single-commodity-network results to the multi commodity case. The second objective is to determine the best placement of flow monitors to obtain the most accurate estimates of traffic flow, as represented by O–D pair traffic volumes in order to detect a disturbance. We followed a multi-criteria approach in defining and evaluating all possible monitor-placement strategies satisfying monitor availability. To assess a traffic pattern, O–D volumes are estimated using the lp-metric for p = 1, 2 and ∞, representing a decision-maker's risk-preference structure. The final objective is to define a disturbance metric providing confident assessments on the occurrence of a flow disturbance. In this regard, we use linear-regression to generate confidence intervals around the expected flow for each O–D pair. This is supplemented by the Fisher Method of Randomization, a non-parametric test, for small networks. Unlike the Fisher-test results, it appears the linear-regression “disturbance metric” is very sensitive to detecting “disturbance.” Preliminary results suggest that among the three lp metrics in O–D estimation, it appears that the best is the l2-metric, which provides the appropriate sensitivity and accuracy. Counter to intuition, it is also observed that the “disturbance” estimation error generally decreases as the number of sampled arcs decreases.
8897506
New architecture for dynamic frame-skipping transcoder
Transcoding is a key technique for reducing the bit rate of a previously compressed video signal. A high transcoding ratio may result in an unacceptable picture quality when the full frame rate of the incoming video bitstream is used. Frame skipping is often used as an efficient scheme to allocate more bits to the representative frames, so that an acceptable quality for each frame can be maintained. However, the skipped frame must be decompressed completely, which might act as a reference frame to nonskipped frames for reconstruction. The newly quantized discrete cosine transform (DCT) coefficients of the prediction errors need to be re-computed for the nonskipped frame with reference to the previous nonskipped frame; this can create undesirable complexity as well as introduce re-encoding errors. In this paper, we propose new algorithms and a novel architecture for frame-rate reduction to improve picture quality and to reduce complexity. The proposed architecture is mainly performed on the DCT domain to achieve a transcoder with low complexity. With the direct addition of DCT coefficients and an error compensation feedback loop, re-encoding errors are reduced significantly. Furthermore, we propose a frame-rate control scheme which can dynamically adjust the number of skipped frames according to the incoming motion vectors and re-encoding errors due to transcoding such that the decoded sequence can have a smooth motion as well as better transcoded pictures. Experimental results show that, as compared to the conventional transcoder, the new architecture for frame-skipping transcoder is more robust, produces fewer requantization errors, and has reduced computational complexity.