Rania Elgohary

A Novel Watermarking Approach for Data Integrity and Non-repudiation in Rational Databases

Keepinglarge scale data sets like data warehouse seems a vital demand of business organizations. Proving copyright, ownership, integrity and non-repudiation have a growing interest of database community. Many watermarking techniques have been proposed in the literature to address these purposes. This paper introduces a new technique WRDN (Watermarking Rational Database with Non-Repudiation) to protect the ownership of relational database by adding only one hidden column with a secret formula where it has the ability to know the latest updates made by users. The calculation of this formula is based on the values of other numeric and textual columns. Moreover, the proposed approach keeps track on the latest updates made to numeric and textual data by users. This approach is compared to two other alternative approaches. The proposed approach survives by 100% against insertion and deletion attacks.

Extracting N-gram terms collocation from tagged Arabic corpus

Information Extraction (IE) is one of the most important Natural Language Processing (NLP) applications, which extracts information such as Named-Entities (NE) and collocation of terms from the corpus. Collocation is a sequence of terms that co-occur together in the corpus. In Arabic Information Extraction, there are many problems because of the complex of Arabics grammar and ambiguity. In general, in linguistics research, the more efficient corpus is the one annotated by Part of Speech Tagging (POST). In this paper, we propose a prototype that extracts collocation of N-gram words (from 2-6 gram) based on the sequence of POST from Arabic Quran corpus. This approach extracts the collocation of N-gram words by matching the input structured pattern of Arabic language versus the Part of Speech Tagging of Quran corpus. The system enables users to select a sequence of tags (2-6 gram) and scope of the corpus source (whole Quran Corpus or specific Surah). To show how the system is beneficial for linguistic research, a set of experiments has been conducted in different scenarios.

Ontology-based Query Expansion for Arabic Text Retrieval

The semantic resources are important parts in the Information Retrieval (IR) such as search engines, Question Answering (QA), etc., these resources should be available, readable and understandable. In semantic web, the ontology plays a central role for the information retrieval, which use to retrieves more relevant information from unstructured information. This paper presents a semantic-based retrieval system for the Arabic text, which expands the input query semantically using Arabic domain ontology. In the proposed approach, the search engine index is represented using Vector Space Model (VSM), and the Arabics place nouns domain ontology has been used which constructed and implemented using Web Ontology Language (OWL) from Arabic corpus. The proposed approach has been experimented on the Arabic Quran corpus, and the experiments show that the approach outperforms in terms of both precision and recall the traditional keyword- based methods.

Ontology-based model for Arabic lexicons: An application of the Place Nouns in the Holy Quran

Ontology is an explicit specification of conceptualization. It defines the terms with specified relationships between them and can be interpreted by both humans and computers. In general, there are scare semantic resources for Arabic language especially in Arabic ontologies. These semantic resources are very essential components in both Information Retrieval and Natural Language Processing applications like search engines, question answering, machine translation, etc. In recent years, many researchers are interested in building Arabic sematic resources, which are then can be exploited by others to build Arabic sematic applications. Recently, a proposed ontological model for “Time Nouns” vocabulary in the Holy Quran was introduced. To share towards building an integrated and unified ontology for Arabic language, in this paper, we are proposing an ontology-based model for Arabic language vocabulary associated with “Place Nouns” in the Holy Quran. This ontology is represented by the Web Ontology Language (OWL), which is the standard language for the semantic web. The ontology will be useful in the knowledge of the Islamic learning, linguistics researches, and Semantic Web applications.

A Generic, Scalable and Fine-Grained Data Access System for Sharing Digital Objects in Honest but Curious Cloud Environments

This paper presents a generic, scalable and fine-grained data access system that realizes the main challenges which hinder the growth of using storage-as-a-service for sharing digital objects offered by honest but curious cloud environments. These main challenges are maintaining data confidentiality, enforcing fine-grained data access control, applying efficient user revocation mechanism, preventing the collusion between users to access unauthorized digital objects, achieving scalability and possessing generic construction desirable feature. In addition, the proposed system avails digital passport which is presented by the user to be granted access to any digital object in the cloud environment. The usage of digital passport minimizes the number of transactions needed to authenticate the specified user. Moreover, the digital passport simplifies the data management for users since the user has to keep his passport only to use it to access the cloud. Furthermore, the digital passport prevents a rejoined user who possesses different attributes to access his previously authorized data. Additionally, the digital passport prohibits the collusion between an authorized user and a revoked one to own the access privileges once assigned to the revoked user. The proposed system exploits public key infrastructure (PKI) to capitalize the usage of offline operations to enhance system performance and to secure the transmission of private data as well as defending man in the middle attack. It should be noted that the implementation of the proposed system has showed the system computational validity.

Building road segments and detecting turns from GPS tracks

Abstract With the wide spreading of geo-aware mobile applications, huge amounts of user-contributed GPS trajectories become available with different levels of accuracy. Constructing road maps from such datasets is one important benefit from this data, and it is required for many applications. There are some challenges related to the inaccuracies incurred on real datasets, such as missing GPS signals, low sampling rate and bad driving behaviour. In this paper, we present a new preprocessing algorithm to address the problems of GPS data. Additionally, we present a clustering-based technique to extract the road map from GPS tracks. Firstly, the tracks are simplified in order to extract road turns and remove the noise data. Then, we adjust the points of the simplified tracks to solve the problems caused by the low sampling rate by moving them closer to the positions of the real turns. Afterwards, a progressive clustering is applied to extract turns and intersections. Finally, we connect them to build the road segments. To ensure the accuracy of our results, we compare the proposed technique with two of the best state-of-the-art methods using a small-scale dataset with inconsistent sampling rate. Another experiment is conducted by extracting a part of the road segments of Egypt using a large-scale dataset with more than 12 million GPS points that are captured with high sampling rate. Experimental results show that our proposed technique exceeds the other methods with regard to F-measure.

A robust cryptographic-based system for secure data sharing in cloud environments: A robust cryptographic-based system for secure data sharing

Over the past few years, the usage of cloud storage services has been growing rapidly to share digital objects between data owner and consumers. However, such environment introduces many data privacy disclosure challenges. These challenges are maintaining data confidentiality, enforcing fine-grained data access control, applying efficient user revocation mechanism, and resisting collusion between system users. In addition, such environment imposes the support of system scalability and generic implementation features. Unfortunately, the proposal of a robust system that accomplishes all data privacy disclosure challenges and the mentioned features is still an open problem. In this paper, a robust cryptographicbased system that solves the stated problem is presented. In addition, the proposed system offers a novel architecture of data consumer digital identity. The presented digital identity solves scalability challenges faced by previous works without complicating data management for both data owner and consumer. Moreover, the proposed digital identity eliminates the need of online presence of data owner and consumer to exchange any information. Furthermore, the proposed system defends man-in-the-middle attack, ensures identity of participants, achieves non-repudiation, and maintains role separation between different participants. Finally, the proposed system implementation proofs the system validity to accomplish all the specified goals with acceptable performance. Copyright

A Large Dataset Enhanced Watermarking Service for Cloud Environments

Preventing data abuses in cloud remains an essential point of the research. Proving the integrity and non-repudiation for large datasets over the cloud has an increasing attention of database community. Having security services based on watermarking techniques that enable permanent preservation for data tuples in terms of integrity and recovery for cloud environments presents the milestone of establishing trust between the data owners and the database cloud services. In this paper, an enhanced secure database service for Cloud environments (EWRDN) is proposed. It based over enhancements on WRDN as a data watermarking approach. The proposed service guarantees data integrity, privacy, and non-repudiation recovering data to its origin. Moreover, it gives data owner more controlling capabilities for their data by enabling tracing users’ activities. Two compression categories to recover data to its origin introduced for the proposed service. Two compression technique (the arithmetic encoding and the transform encoding) chosen to represent each type. For large data sets, it has been proven that, the arithmetic encoding has a fixed recovery ratio equal to one. At the same time, the transform encoding saves space and consumed less time to recover data. Moreover, testing the performance is done of the proposed service versus a large number of tuples, large data set. The performance quantified in terms of processing time and the required memory resources. The enhanced EWRDN service has shown a good performance in our experiments.

Security Issues on Cloud Data Services

In Cloud environments, resources are provided as services to endusers over the internet upon request. Resources’ coordination in the Cloud enables users to reach their resources anywhere and anytime. Ensuring the security in Cloud environment plays an important role, as customers often store important information on Cloud storage services. These services are not always trusted by the data owners. Customers are wondering about the integrity and the availability of their data in the Cloud. Users need to save their data from outsider and insider attackers (i.e. attacker within service providers’ coordination’s). Moreover, any collateral damage or errors of Cloud services provider arises as a concern as well. Most of the vital security needs and issues regarding data Cloud services are mentioned in this chapter. The purpose of this chapter is to examine recent research related to data security and to address possible solutions. Research of employing uncommon security schemes into Cloud environments has received an increasing interest in the literature, although these schemes are neither mature nor rigid yet. This work aspires to promote the use of security protocols due to their ability to reduce security risks that affect users of data Cloud services.

A robust owner-to-user data sharing framework in honest but curious cloud environments

This paper proposes robust owner to user framework for secure data sharing in honest but curious cloud environments. The proposed framework presents a robust solution to accomplish the honest but curious cloud environments desired features such as data confidentiality, scalability, fine-grained data access, efficient user revocation, stateless cloud, preventing colluding users from accessing unauthorized data and generic construction. Furthermore, the proposed framework exploits the public key infrastructure (PKI) desired security features to provide an access control mechanism to prevent colluding users to access unauthorized data. Moreover, the proposed framework counters the attack of the rejoining of a revoked user authorized with different attributes to gain access to his previously authorized data. In addition, the proposed framework prohibits the collusion between an authorized user and a revoked user to possess the access privileges once assigned to the revoked user. This is accomplished with the aid of using dual signature technique. Moreover, the proposed framework capitalizes the existence of PKI to maximize the usage of offline operations to enhance the framework performance. Also, the proposed framework makes use of PKI to offer a secure transmission of private data and defends man in the middle attack. The implementation and the complexity analysis of the proposed framework express the framework practicability.