This thesis aims at an automatic detection of artifacts in optical satellite images such as aliasing, A/D conversion problems, striping, and compression noise; in fact, all blemishes that are unusual in an undistorted image. Artifact detection in Earth observation images becomes increasingly difficult when the resolution of the image improves. For images of low, medium or high resolution, the artifact signatures are sufficiently different from the useful signal, thus allowing their characterization as distortions; however, when the resolution improves, the artifacts have, in terms of signal theory, a similar signature to the interesting objects in an image. Although it is more difficult to detect artifacts in very high resolution images, we need analysis tools that work properly, without impeding the extraction of objects in an image. Furthermore, the detection should be as automatic as possible, given the quantity and ever-increasing volumes of images that make any manual detection illusory. Finally, experience shows that artifacts are not all predictable nor can they be modeled as expected. Thus, any artifact detection shall be as generic as possible, without requiring the modeling of their origin or their impact on an image. Outside the field of Earth observation, similar detection problems have arisen in multimedia image processing. This includes the evaluation of image quality, compression, watermarking, detecting attacks, image tampering, the montage of photographs, steganalysis, etc. In general, the techniques used to address these problems are based on direct or indirect measurement of intrinsic information and mutual information. Therefore, this thesis has the objective to translate these approaches to artifact detection in Earth observation images, based particularly on the theories of Shannon and Kolmogorov, including approaches for measuring rate-distortion and pattern-recognition based compression. The results from these theories are then used to detect too low or too high complexities, or redundant patterns. The test images being used are from the satellite instruments SPOT, MERIS, etc. We propose several methods for artifact detection. The first method is using the Rate-Distortion (RD) function obtained by compressing an image with different compression factors and examines how an artifact can result in a high degree of regularity or irregularity affecting the attainable compression rate. The second method is using the Normalized Compression Distance (NCD) and examines whether artifacts have similar patterns. The third method is using different approaches for RD such as the Kolmogorov Structure Function and the Complexity-to-Error Migration (CEM) for examining how artifacts can be observed in compression-decompression error maps. Finally, we compare our proposed methods with an existing method based on image quality metrics. The results show that the artifact detection depends on the artifact intensity and the type of surface cover contained in the satellite image.

The Internet of things (IoT) recently blossomed remarkably and has been transforming the everyday physical entities around us into an ecosystem of information that will enrich our lives in unimaginable ways. Authentication is one of the primary goals of security in the IoT and acts as the main gateway to a secure system which transmits confidential and/or private data.This thesis focuses on a Device-to-Device Mutual Authentication Protocol, designed for the smart home network, which is an essential component of communication in the Internet of Things(IoT). The protocol has been developed based on asymmetric cryptography to authenticate the devices in the network and for the devices to agree on a shared secret session key. In order to ensure the security of a communications session between the devices, the session keys are changed frequently - ideally after every communication session. The proposed scheme has been programmed in HLPSL, simulated and its efficiency verified using the SPAN/ AVISPA tool. When SPAN substantiates the protocol simulation and the attacker simulation, the back-ends of the AVISPA tool verifies the safety and security of the proposed authentication protocol. The thesis also evaluates the protocol's security against the attacks successful against protocols proposed by other researchers. / Graduate / 0544 / 0984 / 0537 / pwilson1@uvic.ca