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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
141

Vaizdų autentiškumo kontrolė / Image Authentication Control

Petreikienė, Vaida 29 May 2006 (has links)
Digital watermarking is the way to solve digital image copyright protection problem. Such a solution is quite new and the need for software, which would ensure image authentication, is huge. Image authentication control area and its relevance are analyzed in this work. Digital watermarking theoretical basics are presented; six algorithms – Cox, Kim, Wang, Xia, Dugad and Zhu – are analyzed. The analysis of similar software was performed; it revealed the predominance of such software products that allows only visible (though transparent) watermarking, and the number of software with a possibility of invisible watermarking is small. The work consists of these main parts: analysis, design, user documentation and experimental research. The main objective of this work was to design and implement image authentication control system. This system has such features: PGM and JPEG format images review, digital watermark generation, embedding, extraction.
142

On Achieving Secure Message Authentication for Vehicular Communications

Zhang, Chenxi January 2010 (has links)
Vehicular Ad-hoc Networks (VANETs) have emerged as a new application scenario that is envisioned to revolutionize the human driving experiences, optimize traffic flow control systems, etc. Addressing security and privacy issues as the prerequisite of VANETs' development must be emphasized. To avoid any possible malicious attack and resource abuse, employing a digital signature scheme is widely recognized as the most effective approach for VANETs to achieve authentication, integrity, and validity. However, when the number of signatures received by a vehicle becomes large, a scalability problem emerges immediately, where a vehicle could be difficult to sequentially verify each received signature within 100-300 ms interval in accordance with the current Dedicated Short Range Communications (DSRC) protocol. In addition, there are still some unsolved attacks in VANETs such as Denial of Service (Dos) attacks, which are not well addressed and waiting for us to solve. In this thesis, we propose the following solutions to address the above mentioned security related issues. First of all, to address the scalability issues, we introduce a novel roadside unit (RSU) aided message authentication scheme, named RAISE, which makes RSUs responsible for verifying the authenticity of messages sent from vehicles and for notifying the results back to vehicles. In addition, RAISE adopts the k-anonymity property for preserving user privacy, where a message cannot be associated with a common vehicle. Secondly, we further consider the situation that RSUs may not cover all the busy streets of a city or a highway in some situations, for example, at the beginning of a VANETs' deployment period, or due to the physical damage of some RSUs, or simply for economic considerations. Under these circumstances, we further propose an efficient identity-based batch signature verification scheme for vehicular communications. The proposed scheme can make vehicles verify a batch of signatures once instead of one after another, and thus it efficiently increases vehicles' message verification speed. In addition, our scheme achieves conditional privacy: a distinct pseudo identity is generated along with each message, and a trust authority can trace a vehicle's real identity from its pseudo identity. In order to find invalid signatures in a batch of signatures, we adopt group testing technique which can find invalid signatures efficiently. Lastly, we identify a DoS attack, called signature jamming attack (SJA), which could easily happen and possibly cause a profound vicious impact on the normal operations of a VANET, yet has not been well addressed in the literature. The SJA can be simply launched at an attacker by flooding a significant number of messages with invalid signatures that jam the surrounding vehicles and prevent them from timely verifying regular and legitimate messages. To countermeasure the SJA, we introduces a hash-based puzzle scheme, which serves as a light-weight filter for excluding likely false signatures before they go through relatively lengthy signature verification process. To further minimize the vicious effect of SJA, we introduce a hash recommendation mechanism, which enables vehicles to share their information so as to more efficiently thwart the SJA. For each research solution, detailed analysis in terms of computational time, and transmission overhead, privacy preservation are performed to validate the efficiency and effectiveness of the proposed schemes.
143

Analysis of institutional level identity control strategies in distance education environment

Amigud, Alexander 28 March 2013 (has links)
Physical separation of students and instructors creates the gap of anonymity. The ability of academic institutions to authenticate students and their academic work at various points during a course is necessary for preserving not only the perceived credibility but also for public safety. This study examines the question of what measures universities with large distance education programs employ to align identity of learners with the academic work they do, as well as examines effectiveness, challenges and barriers to their implementation. The research is undertaken using a multiple case approach and analyzes survey data collected from academic administrators at five officially accredited post secondary institutions in three countries. They are: Athabasca University, Open University UK, Penn State University World Campus, University of Maryland University College and eConcordia– Concordia University's distance learning facility. This study is not an exhaustive attempt to examine all aspect of academic integrity, but rather to create awareness about various learner authentication strategies and also outline challenges and advantages that these measure entail. This study confirms that secure learner authentication in distance education environment is possible. A combination of technology and administrative procedures may facilitate a secure testing environment. Furthermore, with greater pressure to enhance security of learner authentication, the openness of open learning is challenged and may change as we know it. / 2013-05
144

MUTUAL AUTHENTICATION SCHEME FOR MOBILE RFID SYSTEMS

Allahem, Hisham 28 March 2013 (has links)
Radio Frequency Identification (RFID) systems are rapidly becoming popular in a variety of applications such as supply chain management, storage management and healthcare. Such a system consists of a tag with a unique identifier, a tag reader and a backend server. Due to the system's limited computational resources, it can be subject to various types of attacks. This can exacerbate when the reader itself is mobile. The objective of this thesis is to propose a mutual authentication scheme for mobile RFID systems. Our proposed scheme uses a shared encryption key generated and updated by the mobile reader to authenticate the system entities. The encryption keys are updated at the end of each authentication session. Experimental results show that the proposed scheme meets the security and privacy goals, and resists known attacks on mobile RFID systems
145

Dimensionality Reduction in the Creation of Classifiers and the Effects of Correlation, Cluster Overlap, and Modelling Assumptions.

Petrcich, William 31 August 2011 (has links)
Discriminant analysis and random forests are used to create models for classification. The number of variables to be tested for inclusion in a model can be large. The goal of this work was to create an efficient and effective selection program. The first method used was based on the work of others. The resulting models were underperforming, so another approach was adopted. Models were built by adding the variable that maximized new-model accuracy. The two programs were used to generate discriminant-analysis and random forest models for three data sets. An existing software package was also used. The second program outperformed the alternatives. For the small number of runs produced in this study, it outperformed the method that inspired this work. The data sets were studied to identify determinants of performance. No definite conclusions were reached, but the results suggest topics for future study.
146

Applications of Quantum Cryptography

Nagy, Naya 12 March 2010 (has links)
This thesis extends the applicability of quantum cryptography. First, we prove that quantum cryptography at least equals classical cryptography in an important area, namely authentication. The quantum key distribution protocols presented here show that, contrary to previous belief, authentication can be done with quantum methods only. In addition, we have designed quantum security systems in unconventional settings. The security of sensor networks poses specific challenges, as the sensor nodes in particular can be physically picked up by the intruder. Our scheme protects both the integrity of the communication messages and it also protects the identity of the nodes, such that a reading intrusion of a node is detectable. The problem of access control in a hierarchy refers to a large number of users, organized in a hierarchy, having selective access rights to a database. Our quantum solution introduces quantum keys to the effect that the cryptographic scheme is dynamically adaptable to changes in the user structure, and it exhibits increased security levels. To the best of our knowledge, this thesis is the first to introduce quantum keys, that is secret keys defined by an array of qubits. We show that quantum keys make it possible for two parties to communicate with one-time pads without having to meet in advance. Also, opposite to previous cryptographic ``common sense", the security level of a quantum cryptosystem with quantum keys and quantum messages increases while being used, meaning the security increases over time. / Thesis (Ph.D, Computing) -- Queen's University, 2010-03-12 11:38:07.086
147

A dynamic trust-based context-aware secure authentication framework for pervasive computing environments

Abi-Char, Pierre 30 March 2010 (has links) (PDF)
To provide personalized services to users in pervasive environments, we should consider both user's privacy, trust and security requirements. Traditional authentication and access control mechanisms are not able to adapt their security policies to a changing context while insuring privacy and trust issues. This thesis introduces a new global vision for the protection of pervasive environments, based on context-aware principle. The aim of this thesis is to get a flexible and scalable framework including user authentication, user privacy preserving and trust management in order to optimize the access control strategy to personalized services. The first contribution include the proposal of a mutual authentication protocol supported by both robust key establishment schemes based on elliptic curves (MaptoPoint/Curve algorithm, Weil Pairing) and a dynamic model based on attributes issued from contextual data. The second contribution include the design of a new architecture built on an attribute based model and organized over 3 layers: the privacy control layer which insure the protection of the user private life by controlling their personal data, the access layer which associate authentication and access control processes while providing mechanisms dedicated to trust parameters management , and finally the service layer for service access management according to the user profile and his environment. The third contribution the implementation and the deployment of a prototype within the service delivery platform in Handicom lab of Telecom & Management SudParis.
148

Chaos Based RFID Authentication Protocol

Chung, Harold 17 June 2013 (has links)
Chaotic systems have been studied for the past few decades because of its complex behaviour given simple governing ordinary differential equations. In the field of cryptology, several methods have been proposed for the use of chaos in cryptosystems. In this work, a method for harnessing the beneficial behaviour of chaos was proposed for use in RFID authentication and encryption. In order to make an accurate estimation of necessary hardware resources required, a complete hardware implementation was designed using a Xilinx Virtex 6 FPGA. The results showed that only 470 Xilinx Virtex slices were required, which is significantly less than other RFID authentication methods based on AES block cipher. The total number of clock cycles required per encryption of a 288-bit plaintext was 57 clock cycles. This efficiency level is many times higher than other AES methods for RFID application. Based on a carrier frequency of 13.56Mhz, which is the standard frequency of common encryption enabled passive RFID tags such as ISO-15693, a data throughput of 5.538Kb/s was achieved. As the strength of the proposed RFID authentication and encryption scheme is based on the problem of predicting chaotic systems, it was important to ensure that chaotic behaviour is maintained in this discretized version of Lorenz dynamical system. As a result, key boundaries and fourth order Runge Kutta approximation time step values that are unique for this new mean of chaos utilization were discovered. The result is a computationally efficient and cryptographically complex new RFID authentication scheme that can be readily adopted in current RFID standards such as ISO-14443 and ISO-15693. A proof of security by the analysis of time series data obtained from the hardware FPGA design is also presented. This is to ensure that my proposed method does not exhibit short periodic cycles, has an even probabilistic distribution and builds on the beneficial chaotic properties of the continuous version of Lorenz dynamical system.
149

Methodologies in Digital Watermarking: Robust and Reversible Watermarking Techniques for Authentication, Security and Privacy Protection

Guo, Xin Cindy 24 February 2009 (has links)
The advances in recording, editing and broadcasting multimedia content in digital form motivate the protection of digital information against illegal use, manipulation and distribution. This thesis work focuses on one aspect of digital rights management (DRM), namely digital watermarking. Specifically, we study its use in copy protection, tamper detection and information hiding. We introduce three application-specific digital watermarking techniques. The first two algorithms, based on embedding film grain like noise and signal dependent watermarks, respectively, are designed for authentication applications. The advantage is that they are able to detect malicious tampering while being robust against content-preserving processes such as compression, filtering and additive noise. The third method, a reversible watermarking technique, is designed so that sensitive personal information can be embedded in medical images. Simulation results show that our proposed method outperforms other approaches in the available literature in terms of image quality and computational complexity.
150

Methodologies in Digital Watermarking: Robust and Reversible Watermarking Techniques for Authentication, Security and Privacy Protection

Guo, Xin Cindy 24 February 2009 (has links)
The advances in recording, editing and broadcasting multimedia content in digital form motivate the protection of digital information against illegal use, manipulation and distribution. This thesis work focuses on one aspect of digital rights management (DRM), namely digital watermarking. Specifically, we study its use in copy protection, tamper detection and information hiding. We introduce three application-specific digital watermarking techniques. The first two algorithms, based on embedding film grain like noise and signal dependent watermarks, respectively, are designed for authentication applications. The advantage is that they are able to detect malicious tampering while being robust against content-preserving processes such as compression, filtering and additive noise. The third method, a reversible watermarking technique, is designed so that sensitive personal information can be embedded in medical images. Simulation results show that our proposed method outperforms other approaches in the available literature in terms of image quality and computational complexity.

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