There is, I think, something ethereal about i —the square root of minus one. I remember first hearing about it at school. It seemed an odd beast at that time—an intruder hovering on the edge of reality.

Usually familiarity dulls this sense of the bizarre, but in the case of i it was the reverse: over the years the sense of its surreal nature intensified. It seemed that it was impossible to write mathematics that described the real world in …

I and i

The objective of this paper is to give a comprehensive introduction to applied cryptography with an engineer or computer scientist in mind. The emphasis is on the knowledge needed to create practical systems which supports integrity, confidentiality, or authenticity. Topics covered includes an introduction to the concepts in cryptography, attacks against cryptographic systems, key use and handling, random bit generation, encryption modes, and message authentication codes. Recommendations on algorithms and further reading is given in the end of the paper. This paper should make the reader able to build, understand and evaluate system descriptions and designs based on the cryptographic components described in the paper.

[서평]「Applied Cryptography」

Object-oriented analysis

The Convolution Transform. By Hirschmann & Widder . Pp. x + 268. 45s. 1955. (Princeton University Press. London : Cumberlege)

There is no escaping fact that a huge amount of unexploited resources lies underwater which covers almost 70% of the Earth. Yet, the aquatic world has mainly been unaffected by the recent advances in the area of wireless sensor networks (WSNs) and their pervasive penetration in modern day research and industrial development. The current pace of research in the area of underwater sensor networks (UWSNs) is slow due to the difficulties arising in transferring the state-of-the-art WSNs to their underwater equivalent. Maximum underwater deployments rely on acoustics for enabling communication combined with special sensors having the capacity to take on harsh environment of the oceans. However, sensing and subsequent transmission tend to vary as per different subsea environments; for example, deep sea exploration requires altogether a different approach for communication as compared to shallow water communication. This paper particularly focuses on comprehensively gathering most recent developments in UWSN applications and their deployments. We have classified the underwater applications into five main classes, namely, monitoring, disaster, military, navigation, and sports, to cover the large spectrum of UWSN. The applications are further divided into relevant subclasses. We have also shown the challenges and opportunities faced by recent deployments of UWSN.

https://journals.sagepub.com/doi/pdf/10.1155/2015/896832

Underwater sensor network applications: a comprehensive survey

Current database practitioners cannot easily store information about transient phenomena using existing commercial off-the-shelf tools, because vendors do not support temporal database characteristics. This paper describes a practical problem where a relational database must record a series of events that occur over a given time span, without any modification to the underlying database management system. The database must be able to perform queries on the temporal information of an event occurrence. However, the database must also manage overriding events which take precedence over previously scheduled events, while maintaining knowledge of the overridden event. A basic approach to the problem is discussed, which is conceptually simple but cannot efficiently record the required information, nor can it cope with complex overriding event scenarios. We propose a second approach that models the events using time spans. The time span approach is then refined to create a third scheme that can efficiently handle complex overriding event scenarios. The two time span approaches result in significant storage gains compared to the first approach. However, the storage gains come with a trade-off in efficiency for data manipulation queries. The proposed approach is implementable with current relational standards (and SQL), and does not have the overhead and complexity of a full-scale temporal database.

Maintaining Time Span Information in a Relational Database

￻ Abstract—The Tropical Data Hub (TDH) is a virtual research environment that provides researchers with an eres earch infrastructure to congregate significant tropical data sets for data reuse, integration, searching, and correlation. However, researchers often require data and metadata synthesis across disciplines for cross� domain analyses and knowledge discovery. A triplestore offers a semantic layer to achieve a more intelligent method of search to support the synthesis requirements by automating latent linkages in the data and metadata. Presently, the benchmarks to aid the decision of which triplestore is best suited for use in an application environment like the TDH are limited to performance. This paper describes a new evaluation tool developed to analyze both features and performance. The tool comprises a weighted decision matrix to evaluate the interoperability, functionality, performance, and support availability of a range of integrated and native triplestores to rank them according to requirements of the TDH.

/pdf/a-decision-matrix-for-the-evaluation-of-triplestores-for-use-lpsy838tjg.pdf

A Decision Matrix for the Evaluation of Triplestores for Use in a Virtual Research Environment

Dynamic traitor tracing schemes are used to trace the source of piracy in broadcast environments such as cable
TV. Dynamic schemes divide content into a series of watermarked segments that are then broadcast. The broadcast provider can adapt the watermarks according to the pirate's response and eventually trace him/her. As dynamic algorithms are deterministic, for a given set of inputs, the tracing algorithm will execute exactly the same way each time. An adversary can use this knowledge to ensure that the tracing algorithm is forced into executing at its worst case bound. In this paper we review dynamic traitor tracing schemes and describe why determinism is a problem. We amend several existing dynamic tracing algorithms by incorporating randomised decisions. This eliminates any advantage an adversary has in terms of the aforementioned attack, as he/she no longer knows exactly how the tracing algorithm will execute. Simulations show that the randomising modifications influence each dynamic algorithm to run at its average case complexity in terms of tracing time. We provide an efficiency analysis of the amended algorithms and give some recommendations for reducing overhead.

Randomised dynamic traitor tracing

Dynamic traitor tracing schemes are used to trace the source of piracy in broadcast environments such as cable TV. Dynamic schemes divide content into a series of watermarked segments that are then broadcast. The broadcast provider can adapt the watermarks according to the pirate's response and eventually trace him/her. As dynamic algorithms are deterministic, for a given set of inputs, the tracing algorithm will execute exactly the same way each time. An adversary can use this knowledge to ensure that the tracing algorithm is forced into executing at its worst case bound. In this paper we review dynamic traitor tracing schemes and describe why determinism is a problem. We ammend several existing dynamic tracing algorithms by incorporating randomised decisions. This eliminates any advantage an adversary has in terms of the aforementioned attack, as he/she no longers knows exactly how the tracing algorithm will execute. Simulations show that the randomising modifications influence each dynamic algorithm to run at its average case complexity in terms of tracing time. We provide an efficiency analysis of the amended algorithms and give some recommendations for reducing overhead.

/pdf/randomised-dynamic-traitor-tracing-gymzql8ef1.pdf

Randomised Dynamic Traitor Tracing

The Tropical Data Hub (TDH) as an e-Research initiative to provide a data hosting infrastructure to congregate significant tropical environmental data sets. Tropical regions support some of the world's most diverse and unique ecosystems. However, these sensitive areas are coming under increased pressures from human activities, which significantly threaten their sustainability into the future. Therefore, a need exists for more informed use of environmental monitoring procedures to help better manage tropical regions. At present data is collected in disjoint repositories and is not visible/accessible for reuse by other lines of enquiry. Without this data being publicised, many opportunities are missed for holistic discovery of major trends that influence tropical ecosystems. The TDH serves as a focal point for amalgamating disparate data sources to facilitate data reuse, integration/searching and knowledge discovery by environmental researchers and government departments. This will provide researchers and planners access to extensive and readily available data that can be used to give a more accurate representation of the state of tropical regions and allow for more suitable environmental management practices to be devised. We present two visualisation tools that model data from the Tropical Data Hub. The first is for assessing land space across Northern Australia and the second is a system to rapidly assess the potential impacts of climate change on global biodiversity.

Jarrod Trevathan

Papers

Maintaining Time Span Information in a Relational Database

A Decision Matrix for the Evaluation of Triplestores for Use in a Virtual Research Environment

Randomised dynamic traitor tracing

Randomised Dynamic Traitor Tracing

The Tropical Data Hub (TDH) – a virtual research environment for tropical science knowledge innovation and discovery