Data Encryption and Hashing Schemes for Multimedia Protection

There are millions of people using social networking sites like Facebook, Google+, and Youtube every single day across the entire world for sharing photos and other digital media. Unfortunately, sometimes people publish content that does not belong to them. As a result, there is an increasing demand for quality software capable of providing maximum protection for copyrighted material. In addition, confidential content such as medical images and patient records require high level of security so that they can be protected from unintended disclosure, when transferred over the Internet. On the other hand, decreasing the size of an image without significant loss in quality is always highly desirable. Hence, the need for efficient compression algorithms. This thesis introduces a robust method for image compression in the shearlet domain. Motivated by the outperformance of the Discrete Shearlet Transform (DST) compared to the Discrete Wavelet Transform (DWT) in encoding the directional information in images, we propose a DST-based compression algorithm that provides not only a better quality in terms of image approximation and compression ratio, but also increases the security of images via the Advanced Encryption Standard. Experimental results on a slew of medical images illustrate an improved performance in image quality of the proposed approximation approach in comparison to DWT, and also demonstrate its robustness against a variety of tests, including randomness, entropy, key sensitivity, and input sensitivity. We also present a 3D mesh hashing technique using spectral graph theory. The main idea is to partition a 3D model into sub-meshes, followed by the generation of the Laplace-Beltrami matrix of each sub-mesh, and the application of eigen-decomposition. This, in turn, is followed by the hashing of each sub-mesh using Tsallis entropy. The experimental results using a benchmark 3D models demonstrate the effectiveness of the proposed hashing scheme

Research on digital image watermark encryption based on hyperchaos

The digital watermarking technique embeds meaningful information into one or more watermark images hidden in one image, in which it is known as a secret carrier. It is difficult for a hacker to extract or remove any hidden watermark from an image, and especially to crack so called digital watermark. The combination of digital watermarking technique and traditional image encryption technique is able to greatly improve anti-hacking capability, which suggests it is a good method for keeping the integrity of the original image. The research works contained in this thesis include: (1)A literature review the hyperchaotic watermarking technique is relatively more advantageous, and becomes the main subject in this programme. (2)The theoretical foundation of watermarking technologies, including the human visual system (HVS), the colour space transform, discrete wavelet transform (DWT), the main watermark embedding algorithms, and the mainstream methods for improving watermark robustness and for evaluating watermark embedding performance. (3) The devised hyperchaotic scrambling technique it has been applied to colour image watermark that helps to improve the image encryption and anti-cracking capabilities. The experiments in this research prove the robustness and some other advantages of the invented technique. This thesis focuses on combining the chaotic scrambling and wavelet watermark embedding to achieve a hyperchaotic digital watermark to encrypt digital products, with the human visual system (HVS) and other factors taken into account. This research is of significant importance and has industrial application value

Introductory Computer Forensics

INTERPOL (International Police) built cybercrime programs to keep up with emerging cyber threats, and aims to coordinate and assist international operations for ?ghting crimes involving computers. Although signi?cant international efforts are being made in dealing with cybercrime and cyber-terrorism, ?nding effective, cooperative, and collaborative ways to deal with complicated cases that span multiple jurisdictions has proven dif?cult in practic

Forensic analysis of large capacity digital storage devices

Digital forensic laboratories are failing to cope with the volume of digital evidence required to be analysed. The ever increasing capacity of digital storage devices only serves to compound the problem. In many law enforcement agencies a form of administrative triage takes place by simply dropping perceived low priority cases without reference to the data itself. Security agencies may also need days or weeks to analyse devices in order to detect and quantify encrypted data on the device.The current methodology often involves agencies creating a hash database of files where each known contraband file is hashed using a forensic hashing algorithm. Each file on a suspect device is similarly hashed and the hash compared against the contraband hash database. Accessing files via the file system in this way is a slow process. In addition deleted files or files on deleted or hidden partitions would not be found since their existence is not recorded in the file system.This thesis investigates the introduction of a system of triage whereby digital storage devices of arbitrary capacity can be quickly scanned to identify contraband and encrypted content with a high probability of detection with a known and controllable margin of error in a reasonable time. Such a system could classify devices as being worthy of further investigation or not and thus limit the number of devices being presented to digital forensic laboratories for examination.A system of triage is designed which bypasses the file system and uses the fundamental storage unit of digital storage devices, normally a 4 KiB block, rather than complete files. This allows fast sampling of the storage device. Samples can be chosen to give a controllable margin of error. In addition the sample is drawn from the whole address space of the device and so deleted files and partitions are also sampled. Since only a sample is being examined this is much faster than the traditional digital forensic analysis process.In order to achieve this, methods are devised that allow firstly the identification of 4 KiB blocks as belonging to a contraband file and secondly the classification of the block as encrypted or not. These methods minimise both memory and CPU loads so that the system may run on legacy equipment that may be in a suspect’s possession. A potential problem with the existence of blocks that are common to many files is quantified and a mitigation strategy developed.The system is tested using publically available corpora by seeding devices with contraband and measuring the detection rate during triage. Results from testing are positive, achieving a 99% probability of detecting 4 MiB of contraband on a 1 TB device within the time normally assigned for the interview of the device owner. Initial testing on live devices in a law enforcement environment has shown that sufficient evidence can be collected in under four minutes from a 1TB device to allow the equipment to be seized and the suspect to be charged.This research will lead to a significant reduction in the backlog of cases in digital forensic laboratories since it can be used for triage within the laboratory as well as at the scene of crime