Imad Fakhri Taha Al Shaikhli

Protection of Integrity and Ownership of PDF Documents Using Invisible Signature

Distributing digital document through insecure channel leads to the question of the integrity and the ownership of the file on the receivers side. Employing hash function and digital signature algorithms solves the difficulties of the receiver to proof the approval of the document from the sender as well as detecting if the file has been altered by illegitimate parties. In this paper, a method to attach digital signature in Portable Document File (PDF) as invisible watermark is proposed. We show that the space character that splits the field in cross-reference table can be overwritten without corrupting the file. The method to embed and extract the signature are proven to be efficient, since the offset index for cross-reference table are available at the end of the file. Our proposed method to embed the signature in the PDF file does not increase the size of the file and offer flexibility for the user to implements the digital signature scheme of his/her own preference.

A Framework for Evaluating Skyline Queries over Incomplete Data

Research interest in skyline queries has been significantly increased over the years, as skyline queries can be utilized in many contemporary applications, such as multi-criteria decision-making system, decision support system, recommendation system, data mining, and personalized systems. Skyline queries return data item that is not dominated by any other data items in all dimensions (attributes). Most of the existing skyline approaches assumed that database is complete and values are present during the skyline process. However, such assumption is not always to be true, particularly in a real world database where values of data item might not be available (missing) in one or more dimensions. Thus, the incompleteness of the data impacts negatively on skyline process due to losing the transitivity property which leads into the issue of cyclic dominance. Therefore, applying skyline technique directly on an incomplete database is prohibitive and might result into exhaustive pairwise comparison. This paper presents an approach that efficiently evaluates skyline queries in incomplete database. The approach aims at reducing the number of pairwise comparisons and shortens the searching space in identifying the skylines. Several experiments have been conducted to demonstrate that our approach outperforms the previous approach through producing a lower number of pairwise comparisons. Furthermore, the result also illustrates that our approach is scalable and efficient.

An improved full search block matching algorithm for imaging applications

Full search block matching algorithm (FSBMA) for motion estimation requires a high level of computations, rendering the technique unsuitable for real-time imaging applications. To alleviate this problem, extensive research for developing faster motion estimation techniques has been conducted. As expected, reducing computational complexity comes at the expense of the image quality. This paper presents an improved full search block matching algorithm (IFSBMA) that reduces the computational load without significant degradation of the image quality. In comparison with other full search algorithms, the proposed technique reduces computational intensity with almost 90% for video bowing and 95% for video test. Experimental results also show that the computational complexity of the proposed technique is relatively higher than that of the four-step (FSS) and the three-step (TSS) algorithms. However, the sum of absolute difference (SAD) of the proposed technique is better than the SAD of the FSS and the TSS.

HISEC: A New Lightweight Block Cipher Algorithm

Lightweight block cipher algorithms are vital for constrained environment. There are many applications need secured lightweight block cipher algorithm like credit card, E-passport and etc. In this paper, we propose a new lightweight block cipher algorithm called HISEC. We applied three attacks differential, integral attacks and boomerang attack. The results showed that HISEC is better than some lightweight algorithms.

Dynamic linear feedback shift registers: A review

An improvement in the security of stream cipher is achieved by introducing dynamic polynomial switching in the Linear Feedback Shift Registers. Several researches declared that this introduction enhances the stream ciphers immunity to cryptanalysis. This paper aims to provide a comprehensive survey that summarizes the recent approaches for applying this idea for the purpose of shaping a clear vision of these designs. This vision will assist the development process of new designs.

OLBCA: A New Lightweight Block Cipher Algorithm

Light weight block cipher algorithms are vital for constrained environment. It is easy to propose an algorithm that optimize any two factors like (security and cost), (security and performance) and (cost and performance) but it is difficult to optimize three factors together at the same time. In this paper, we propose a new lightweight block cipher algorithm called OLBCA. PRESENT lightweight block cipher algorithm is chosen because it is one of the most common and famous lightweight algorithms. Also, the International Organization for Standardization and the International Electro technical Commission (ISO/IEC 29192-2:2012) declared that PRESENT as a new international standard for lightweight cryptographic methods. We applied three attacks differential, integral attacks and boomerang attack. The results showed that OLBCA is better than PRESENT algorithms in three factors.

Processing Skyline Queries in Incomplete Database: Issues, Challenges and Future Trends

In many contemporary database applications such as multi-criteria decision-making and real-time decision-support applications, data mining, e-commerce and recommendation systems, users need query operators to process the data aiming at finding the results that best fit with their preferences. Skyline queries are one of the most predominant query operators that privileges to find the query results that return only those data items whose dimension vector is not dominated by any other data item in the database. Because of their usefulness and ubiquity, skyline queries have been incorporated into different types of databases such as complete, incomplete and uncertain. This paper attempts to survey and analyze the previous works proposed to process skyline queries in the incomplete database. The discussion focuses on examining these approaches highlighting the strengths and the weaknesses of each work. Besides, we also discuss in detail the current challenges in processing skyline queries in the incomplete database and investigate the impact of incomplete data on skyline operation. A summary of the most well-known works has been reported to identify the limitations of these works. Some recommendations and future work directions have been drawn to help researchers investigate the unsolved problems related to skyline queries in a database system.

Setting-up a Sulh-based, community mediation-type of online dispute resolution (ODR) in Malaysia

Islam is a way of life that guides the Muslims from all perspectives, and as portion of Islam, it also promotes peace and conciliation in resolving disputes. The Al-Quran provides guidelines in dispute resolution through a third party called Sulh. Sulh refers to the process of mediation, arbitration and reconciliation that takes place when the parties involved agree on a process of resolving a dispute with a third party mediator, who eventually will ensure that both disputed parties will be satisfied by the outcomes. This work is focused on community mediation, which involved with the disputes between the community members. In Malaysia, Sulh were actually practiced by the Malays prior to the time of the Portuguese, the Dutch and the British. The session will be conducted by a third party who normally a respected and elder person in the society, whom also held the position as the headman (Penghulu or Ketua Kampung) or Imam (a religious leader). Nowadays, given the plural society of Malaysia, and the era of Internet, it is crucial for Sulh to be available online. With the use of ICT tools, Sulh can be promoted to society, and if it is a part of e-government efforts, then it will encourage the society to be involved with the governments mission. The online Sulh will not merely act as an interface for those parties involved. The challenges of making the online system secured, the correct ways of ensuring the data accuracy, understanding on methods that will be used for data propagation (among others), are existed in the domain of Computer Science (CS). There are many possible CS approaches, but the work will focus on Computational Intelligence (CI) techniques, with special interest in connectionist models.

Improving PRESENT Lightweight Algorithm

Lightweight block cipher algorithms are vital for constrained environment. Substitution box (S-box) is the essential constituent of many lightweight block cipher algorithms and it is the only nonlinear part. It is proficient to create confusion in the plaintext during the process of encryption. In this research, a new way of key dependent S-box is proposed by choosing one S-box out of 16 good S-boxes. Preliminary analysis of linear and differential cryptanalysis is showing that the proposed algorithm is more secure than fixed PRESENT S-box. Also, the complexity of the PRESENT S - box in each round is 28 while the complexity of the proposed algorithm S-box is 212 in each round.

Security of Present S-box

Resource efficient cryptographic primitives become fundamental for realizing both security and efficiency in embedded systems like RFID (Radio-Frequency IDentification) tags and sensor nodes. Among those primitives, lightweight block cipher plays a major role to secure RFIDs tag. One of the common lightweight block ciphers is PRESENT. In this paper, we attended both conditions of PRESENT substitution box S-box and those conditions of 4-bit S-box. They were studied and analyzed thoroughly in relation with linear and differential cryptanalysis. The results show that there is conflict in one of the conditions of PRESENT S-box.