886109
XWAVE: Approximate Extended Wavelets for Streaming Data
Wavelet synopses have been found to be of interest in query optimization and approximate query answering. Recently, extended wavelets were proposed by Deligiannakis and Roussopoulos for data sets containing multiple measures. Extended wavelets optimize the storage utilization by attempting to store the same wavelet coecient across dierent measures. This reduces the bookkeeping overhead and more coecients can be stored. An optimal algorithm for minimizing the error in representation and an approximation algorithm for the complementary problem was provided. However, both their algorithms take linear space. Synopsis structures are often used in environments where space is at a premium and the data arrives as a continuous stream which is too expensive to store. In this paper, we give algorithms for extended wavelets which are space sensitive, i.e., use space which is dependent on the size of the synopsis (and at most on the logarithm of the total data) and operates in a streaming fashion. We present better optimal algorithms based on dynamic programming and a near optimal approximate greedy algorithm. We also demonstrate the performance benets of our algorithms compared to previous ones through experiments on real-life and synthetic data sets.
41189424
SQUIRE: Sequential pattern mining with quantities
Discovering sequential patterns is an important problem for many applications. Existing algorithms find qualitative sequential patterns in the sense that only items are included in the patterns. However, for many applications, such as business and scientific applications, quantitative attributes are often recorded in the data, which are ignored by existing algorithms. Quantity information included in the mined sequential patterns can provide useful insight to the users. 
 
In this paper, we consider the problem of mining sequential patterns with quantities. We demonstrate that naive extensions to existing algorithms for sequential patterns are inefficient, as they may enumerate the search space blindly. To alleviate the situation, we propose hash filtering and quantity sampling techniques that significantly improve the performance of the naive extensions. Experimental results confirm that compared with the naive extensions, these schemes not only improve the execution time substantially but also show better scalability for sequential patterns with quantities.
16925677
Multi-level customization in application engineering
Developing mechanisms for mapping features to analysis models.
12552933
TTS without Revocation Capability Secure Against CCA2
A traitor tracing scheme (TTS) deters traitors from giving away their secret keys to decrypt the transmitted data by enabling the system manager to trace at least one of the traitors who participated in the construction of a pirate decoder after confiscating it. In an asymmetric scheme, the system manager is also under suspicion, so the system manager must convince a judge of the implication of the traitors. Recently, Kiayias and Yung proposed an asymmetric public key traitor tracing scheme [13]. However, their scheme does not provide CCA2 security even if a single user is a traitor. That is, their scheme is secure against adaptive chosen ciphertext (CCA2) attack only when there is no traitor. In this paper, we first introduce the security notion against CCA2 attack in a traitor tracing scheme with no revocation capability. This notion is somewhat different from the traditional security notion against CCA2 attack in a two-party encryption scheme [5]. To the best of our knowledge, no security notion against CCA2 attack in a traitor tracing scheme with no revocation capability has been presented. In addition, we modify the Kiayias and Yung’s scheme to achieve security against CCA2 attack under the decision Diffie-Hellman assumption and the collision-resistant hash function assumption.
12867787
I Am Fine but You Are Not: Optimistic Bias and Illusion of Control on Information Security
Information security is a critically important issue in current networked business and work environments. While there is extensive publicity on the increasing incidents of numerous information security breaches and their serious consequences, recent surveys and research on information security repeatedly identify the low levels of user and managerial awareness as a key obstacle to achieving a good information security posture. The main motivation of our research emanates from this contradicting phenomenon: increased vulnerability to information security breaches yet the low level of user and managerial awareness on information security threats. In this research, we study this dissonance by addressing a cognitive bias, optimistic bias, that is, the tendency of people to believe that negative events are less likely to happen to them than to others and that positive events are more likely to happen to them than others. Using a survey, we find that users demonstrate optimistic bias in their risk perceptions associated with information security. This self-serving bias is also found to be related to a perception of controllability with information security threats. These results have practical implications for designing security awareness programs by suggesting that risk communication and management efforts are likely to fail unless they consider this bias.
33288907
Practical Pay-TV Scheme Using Traitor Tracing Scheme for Multiple Channels
A Pay-TV scheme broadcasts a set of services or streams instead of one. That is, a pay-TV scheme is a specific application of a broadcast encryption scheme in which the secret to be broadcast is associated with a number of services. For example, a pay-TV broadcaster offers various channels such as a sports channel, a movie channel, and so on. A traitor tracing scheme is a variant of a broadcast encryption scheme, so can be applied to construct a pay-TV scheme. However, because most known traitor tracing schemes deal with the broadcast of a single stream, a direct extension to multiple streams is too inefficient, i.e., direct extension to an m-stream case would involve an m-fold increase in the user's secret keys. In other words, if the number of streams to be sent increases, the number of secret keys each user must store in a secure memory also linearly increases. Therefore, we require a specific traitor tracing scheme which can be efficiently applied to a pay-TV scheme. We propose a new traitor tracing scheme for multiple channels and its application to a pay-TV scheme. The number of secret keys each user must store in a secure memory is just one regardless of the number of channels and it cannot be changed. Our scheme has a revocation property, i.e., we can revoke some users without redistributing a new secret key to other un-revoked users. Our scheme also provides a so called holding property – we can revoke some users and un-revoke them without redistribution of new keys after some period. This is very useful in a pay-TV scheme since a user may wish to un-subscribe from a channel for some periods and re-subscribe again later. Moreover, our pay-TV scheme is based on a public key traitor tracing scheme. Therefore, any content provider can send encrypted data to users with the public key the system manager provides. Our scheme can also be extended to provide asymmetric property and be secure against the adaptive chosen ciphertext attack.
11427398
New Key Recovery in WAKE Protocol
Wireless authentication and key establishment (WAKE) protocols are essential in mobile communications. The key recovery mechanism may also be required in mobile communication systems for the investigation of serious crimes and for national security. Recently some protocols that give key recovery in the WAKE protocol have been published. In this paper we propose new key recovery protocols that improve previous protocols in security and efficiency.