A Security Analysis of Some Physical Content Distribution Systems

Content distribution systems are essentially content protection systems that protect premium multimedia content from being illegally distributed. Physical content distribution systems form a subset of content distribution systems with which the content is distributed via physical media such as CDs, Blu-ray discs, etc. This thesis studies physical content distribution systems. Specifically, we concentrate our study on the design and analysis of three key components of the system: broadcast encryption for stateless receivers, mutual authentication with key agreement, and traitor tracing. The context in which we study these components is the Advanced Access Content System (AACS). We identify weaknesses present in AACS, and we also propose improvements to make the original system more secure, flexible and efficient

Application of remote sensing method in coal fire identification in Ningwu Coalfield

Coal fire cause serious influence on environment, economy and safety of surrounding area. It is of great significance to accurately identify the scope of coal fire caused by spontaneous combustion in coal field for monitoring and controlling coal fire. Relevant scholars identified the scope of coal fire by extracting surface thermal anomaly or surface deformation information respectively, but due to the single method and means, there are many factors causing the occurrence of coal fire, so the experimental results are not accurate enough. In order to improve the accuracy of coal fire identification, the coal fire identification method combining satellite thermal infrared technology and radar technology is applied to the fire area identification of Ningwu Coalfield in Shanxi Province through practical application research. Firstly, the ASTER–TES(Temperature-Emissivity Separation) algorithm is used to retrieve land surface Temperature from ASTER thermal infrared data at night. At the same time, surface subsidence information is inverted using The Sentinel-1 data of SBAS–InSAR(Small Baseline Subset InSAR) technology, and then the abnormal high temperature area and abnormal settlement area in the study area are extracted by threshold segmentation method, and then the range of suspected coal field fire area is obtained by fusion processing. Finally, the experimental results are compared and verified by the coal fire range determined by the field survey method of measuring radon. The results show that the accuracy of the proposed method is as high as 93.78%, which is 43.29% and 62.23% higher than that of the single temperature inversion method and the settlement anomaly method. However, some fire zones have not been identified, mainly because it is difficult to obtain the threshold of identifying fire zones using surface deformation. The results show that the cooperative identification method of thermal infrared technology and radar technology can effectively overcome the deficiency of single identification method, significantly improve the identification accuracy of coal fire range, and provide a powerful reference for accurately determining the control range of fire area. In order to obtain more comprehensive and accurate range of coal fire, it is necessary to study the characteristics of surface deformation detection method in the future

Exact Maximum Expected Differential and Linear Probability for 2-Round Advanced Encryption Standard (AES)

Provable security of a block cipher against di#erential / linear cryptanalysis is based on the maximum expected di#erential / linear probability (MEDP / MELP) over T 2 core rounds. Over the past few years, several results have provided increasingly tight upper and lower bounds in the case T = 2 for the Advanced Encryption Standard (AES)

Exact maximum expected differential and linear probability for 2round advanced encryption standard (AES),” Cryptology ePrint archive, Report 2005/321

Abstract. Provable security of a block cipher against differential / linear cryptanalysis is based on the maximum expected differential / linear probability (MEDP / MELP) over T ≥ 2 core rounds. Over the past few years, several results have provided increasingly tight upper and lower bounds in the case T = 2 for the Advanced Encryption Standard (AES). We show that the exact value of the 2-round MEDP / MELP for the AES is equal to the best known lower bound: 53/2 34 ≈ 1.656 × 2 −29

An Overview of the Advanced Access Content System (AACS)

The Advanced Access Content System (AACS) is a content distribution system for recordable and pre-recorded media, currently used to protect HD-DVD and Blu-Ray content. AACS builds off of its predecessors, the Content Scramble System (CSS) and Content Protection for Pre-recorded/Recordable media (CPRM/CPPM), adding more robust key distribution and revocation capabilities. In this paper, a concise summary of the lengthy AACS specification for pre-recorded media is provided, with emphasis on how the AACS keys are organized, distributed, and revoked using subset difference trees. A description of the AACS mechanisms for recordable content and on-line content is also provided.