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    Efficient key authentication service for secure end-to-end communications
    (Springer, 2015) N/A; Department of Computer Engineering; N/A; Küpçü, Alptekin; Etemad, Mohammad; Faculty Member; PhD Student; Department of Computer Engineering; College of Engineering; Graduate School of Sciences and Engineering; 168060; N/A
    After four decades of public key cryptography, both the industry and academia seek better solutions for the public key infrastructure. A recent proposal, the certificate transparency concept, tries to enable untrusted servers act as public key servers, such that any key owner can verify that her key is kept properly at those servers. Unfortunately, due to high computation and communication requirements, existing certificate transparency proposals fail to address the problem as a whole. We propose a new efficient key authentication service (KAS). It uses server-side gossiping as the source of trust, and assumes servers are not all colluding. KAS stores all keys of each user in a separate hash chain, and always shares the last ring of the chain among the servers, ensuring the users that all servers provide the same view about them (i.e., no equivocation takes place). Storing users’ keys separately reduces the server and client computation and communication dramatically, making our KAS a very efficient way of public key authentication. The KAS handles a key registration/change operation in O(1) time using only O(1) proof size; independent of the number of users. While the previous best proposal, CONIKS, requires the client to download 100 KB of proof per day, our proposal needs less than 1 KB of proof per key lifetime, while obtaining the same probabilistic guarantees as CONIKS.
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    Evaluation of a mixed reality head-mounted projection display to support motion capture acting
    (Springer, 2018) Kade, Daniel; Lindell, Rikard; Department of Electrical and Electronics Engineering; Department of Media and Visual Arts; Ürey, Hakan; Özcan, Oğuzhan; Faculty Member; Faculty Member; Department of Electrical and Electronics Engineering; Department of Media and Visual Arts; College of Engineering; College of Social Sciences and Humanities; 8579; 12532
    Motion capture acting is a challenging task, it requires trained and experienced actors who can highly rely on their acting and imagination skills to deliver believable performances. This is especially the case when preparation times are short and scenery needs to be imagined, as it is commonly the case for shoots in the gaming industry. To support actors in such cases, we developed a mixed reality application that allows showing digital scenery and triggering emotions while performing. In this paper we tested our hypothesis that a mixed reality head-mounted projection display can support motion capture acting through the help of experienced motion capture actors performing short acting scenes common for game productions. We evaluated our prototype with four motion capture actors and four motion capture experts. Both groups considered our application as helpful, especially as a rehearsal tool to prepare performances before capturing the motions in a studio. Actors and experts indicated that our application could reduce the time to prepare performances and supports the set up of physical acting scenery.
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    Large-scale behavior of end-to-end epidemic message loss recovery1
    (Springer, 2002) N/A; Department of Computer Engineering; Özkasap, Öznur; Faculty Member; Department of Computer Engineering; College of Engineering; 113507
    An important class of large-scale distributed applications is insensitive to small inconsistencies among participants, as long as these events are temporary and not frequent. An efficient way for propagating information to participants in such cases is referred to as epidemic protocols. Epidemic protocols are simple, scale well and robust again common failures, and provide eventual consistency as well. They combine benefits of efficiency in hierarchical data dissemination with robustness in flooding protocols. These communication mechanisms have been mainly used for resolving inconsistencies in distributed database updates, failure detection, message loss recovery in multicast communication, network news distribution, group membership management, scalable system management, and resource discovery. In this paper, we focus on an end-to-end epidemic loss recovery mechanism for multicasting and give our simulation results discussing the performance of the approach in large-scale network settings. 
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    Ransac-based training data selection on spectral features for emotion recognition from spontaneous speech
    (Springer, 2011) Erdem, Çiǧdem Eroǧlu; Erdem, A. Tanju; Department of Computer Engineering; N/A; Erzin, Engin; Bozkurt, Elif; Faculty Member; PhD Student; Department of Computer Engineering; College of Engineering; Graduate School of Sciences and Engineering; 34503; N/A
    Training datasets containing spontaneous emotional speech are often imperfect due the ambiguities and difficulties of labeling such data by human observers. In this paper, we present a Random Sampling Consensus (RANSAC) based training approach for the problem of emotion recognition from spontaneous speech recordings. Our motivation is to insert a data cleaning process to the training phase of the Hidden Markov Models (HMMs) for the purpose of removing some suspicious instances of labels that may exist in the training dataset. Our experiments using HMMs with Mel Frequency Cepstral Coefficients (MFCC) and Line Spectral Frequency (LSF) features indicate that utilization of RANSAC in the training phase provides an improvement in the unweighted recall rates on the test set. Experimental studies performed over the FAU Aibo Emotion Corpus demonstrate that decision fusion configurations with LSF and MFCC based classifiers provide further significant performance improvements. © 2011 Springer-Verlag.
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    Run-time verification of optimistic concurrency
    (Springer, 2010) Qadeer, Shaz; N/A; Department of Computer Engineering; Department of Computer Engineering; Sezgin, Ali; Taşıran, Serdar; Muşlu, Kıvanç; Researcher; Faculty Member; Undergraduate Student; Department of Computer Engineering; N/A; College of Engineering; College of Engineering; N/A; N/A; N/A
    Assertion based specifications are not suitable for optimistic concurrency where concurrent operations are performed assuming no conflict among threads and correctness is cast in terms of the absence or presence of conflicts that happen in the future. What is needed is a formalism that allows expressing constraints about the future. In previous work, we introduced tressa claims and incorporated prophecy variables as one such formalism. We investigated static verification of tressa claims and how tressa claims improve reduction proofs. In this paper, we consider tressa claims in the run-time verification of optimistic concurrency implementations. We formalize, via a simple grammar, the annotation of a program with tressa claims. Our method relieves the user from dealing with explicit manipulation of prophecy variables. We demonstrate the use of tressa claims in expressing complex properties with simple syntax. We develop a run-time verification framework which enables the user to evaluate the correctness of tressa claims. To this end, we first describe the algorithms for monitor synthesis which can be used to evaluate the satisfaction of a tressa claim over a given execution. We then describe our tool implementing these algorithms. We report our initial test results.