Space saving key-lock access control system (abstract only)

Heterogeneous computing utilizing both CPU and FPGA requires access to data in the main memory from both devices. While a typical system relies on software executing on the CPU to orchestrate all data movements between the FPGA and the main memory, our demo presents a complementary FPGA-centric approach that allows gateware to directly access the virtual memory space as part of the executing process without involving the CPU. A caching address translation buffer was implemented alongside the user FPGA gateware to provide runtime mapping between virtual and physical memory addresses. The system was implemented on a commercial off-the-shelf FPGA add-on card to demonstrate the viability of such approach in low-cost systems. Experiment demonstrated reasonable performance improvement when compared to a typical software-centric implementation; while the number of context switches between FPGA and CPU in both kernel and user mode was significantly reduced, freeing the CPU for other concurrent user tasks.

Access control constrains what a user can do directly, as well as what programs executing on behalf of the users are allowed to do. In this way access control seeks to prevent activity that could lead to a breach of security. This article explains access control and its relationship to other security services such as authentication, auditing, and administration. It then reviews the access matrix model and describes different approaches to implementing the access matrix in practical systems, and follows with a discussion of access control policies commonly found in current systems, and a brief consideration of access control administration.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Main memory virtualization is used to expand the effective main memory capacity meaning that more virtual main memory is represented to guest operating systems than physical memory is actually available. This is done by compressing and uncompressing memory pages. Obviously the price for main memory virtualization is a higher CPU utilization, especially when dealing with high workloads. SAP ERP systems represent the backbone of today's enterprises and have a very high resource demand. The combination of main memory virtualization and SAP ERP system is of great importance but has not yet been thoroughly researched. This paper is the first approach to a quantitative research for evaluating the performance impact of memory virtualization on SAP ERP systems. We utilize a synthetic main memory benchmark, called Zachmanntest, to evaluate the performance impact of main memory virtualization on a SAP ERP system. As an exemplary main memory virtualization implementation IBM's Active Memory Expansion is used, where a so called expansion factor can be used to specify the size of the virtual main memory. Performance results show that the greater the expansion factor, the greater the performance impact. Regarding the peak performance, throughput of SAP ERP systems may be decreased till -17%, whereas the overall throughput of such systems may experience a decrease up to -42% when dealing with a very high compression factor.

In this paper we propose the use of the compact data structure k2-treap to process data cubes of Data Warehouses (DWs) into main memory. Compact data structures are data structures that allow compacting the data without losing the capacity of querying them in their compact form. A DW is a data repository to store historical data for decision support, and consists of dimensions and facts. The former are an abstract concept that groups data with a similar meaning, they are modelled as hierarchies of levels, which contain elements. The latter are quantitative data associated to dimensions. A data cube is a typical way to retrieve facts at different levels of granularity (through navigation on dimensions hierarchies). A DW can store terabytes of data, thus the efficient processing of data cubes is key in OLAP (On-line Analytical Processing). We show that by using a compact representation of data cubes and bitmaps to represent dimensions we are able to improve the use of space in main memory, and achieve better performance for query processing.

The safety problem in access matrix models is the one to determine whether or not a given subject can eventually obtain an access privilege to a given object. Unfortunately, little is known about protection systems for which the safety problem is decidable, except for strongly constrained systems (e.g., monotonic systems). Therefore, we propose the Dynamic-Typed Access Matrix Model, which extends Typed Access Matrix model by allowing the type of an object to change dynamically. DTAM model has an advantage that it can describe non-monotonic protection systems for which the safety problem is decidable. In this paper, we formally define DTAM model and then discuss various aspects of it.Keywordsaccess controlaccess matrix modelsafety problemcomputational complexitydecidability

The natural number bias and its role in rational number understanding in children with dyscalculia. Delay or deficit?

Access control to confidential information in pervasive computing environments is challenging for multiple reasons: First, a client requesting access might not know which access rights are necessary in order to be granted access to the requested information. Second, access control must support flexible access rights that include context-sensitive constraints. Third, pervasive computing environments consist of a multitude of information services, which makes simple management of access rights essential. We discuss the shortcomings of existing access-control schemes that rely on either clients presenting a proof of access to a service or services encrypting information before handing the information over to a client. We propose a proofbased access-control architecture that employs hierarchical identity-based encryption in order to enable services to inform clients of the required proof of access in a covert way, without leaking information. Furthermore, we introduce an encryption-based access-control architecture that exploits hierarchical identity-based encryption in order to deal with multiple, hierarchical constraints on access rights. We present an example implementation of our proposed architectures and discuss the performance of this implementation.

ABSTRACTDifficulties with rational numbers have been explained by a natural number bias, where concepts of natural numbers are inappropriately applied to rational numbers. Overcoming this difficulty may require a radical restructuring of previous knowledge. In order to capture this development, we examined third- to fifth-grade students' understanding of the size of rational numbers across a 1-year period. On three occasions, students answered a test about the size of decimals and fractions. Latent transition analysis allowed profiling five different rational number size concepts and mapping students' developmental trajectories during the early learning of this topic. Development from natural number-based reasoning to mathematically correct understanding was almost nonexistent during this time period. Instead, students appear to move through intermediary concepts. Locating these temporary and mediating number concepts supports the idea of a slow and gradually developing conceptual change in rational numbers.

An access control system is a collection of rules used to restrict the visibility, access, and usage of the data resources in an institutional environment. When implemented, these rules provide a policy for achieving the security of the institution, establishing a hierarchy of the employees depending on their rights over the institution’s data resouces. An access control system is based on two fundamental concepts: authentication (that verifyies the user's identity) and authorization (that provides a hierarchy of the employees according to their access rights over the institutional resources). Among the most commonly used access control models we recall Role-Based Access Control (RBAC), in which users with the same role have equal access rights to data resources, Discretionary Access Control (DAC), in which the system owner decides which user has access to system resources, and Mandatory Access Control (MAC), in which a series of rules, with a high level of security established by a predefined authority, are used. In this article, we will study the last two models, namely DAC and MAC, along with their main implementations: Access Control Matrix and the Take-Grant models for DAC, BIBA and Bell-LaPadula for MAC.

There are several security problems arising from the characteristics of IoT, and one of them is weak access control. Traditional access control models require one centralized authority that stores all the information for access control and validates access rights. This single point of failure in IoT access control could lead to situations where a single breach can cause sensitive information leakage across the entire system. Various studies have been conducted to mitigate this security risk by introducing a decentralized architecture based on blockchain technology called BBAC. However, most BBAC models consider only a simple access control situation, which can lead to a “the Greatest privilege problem”. This study proposes a novel access control model that enforces minimum privilege to an access token by the division and modification of access rights. As a result, we contributed to enhancing the practicality of the BBAC and mitigating risks that may arise in the delegation process.

The Internet of things (IoT) is an active, real-world area in need of more investigation. One of the top weaknesses in security challenges that IoTs face, the centralized access control server, which can be a single point of failure. In this paper, Dynamic-IoTrust, a decentralized access control smart contract based aims to overcome distrusted, dynamic, trust and authentication issues for access control in IoT. It also integrates dynamic trust value to evaluate users based on behavior. In particular, the Dynamic-IoTrust contains multiple Main Smart Contract, one Register Contract, and one Judging Contract to achieve efficient distributed access control management. Dynamic-IoTrust provides both static access rights by allowing predefined access control policies and also provides dynamic access rights by checking the trust value and the behavior of the user. The system also provides to detected user misbehavior and make a decision for user trust value and penalty. There are several levels of trusted users to access the IoTs device. Finally, the case study demonstrates the feasibility of the Dynamic-IoTrust model to offer a dynamic decentralized access control system with trust value attribute to evaluate the internal user used IoTs devices.

Virtual memory was developed to automate the movement of program code and data between main memory and secondary storage to give the appearance of a single. This technique greatly simplified the programmer’s job, particularly when program code and data exceeded the main memory’s size. In modern operating system, secure file system can protect confidential data from unauthorized access. However, once an authorized process has accessed data from a cryptographic file system, the data can appear as plaintext in the unprotected virtual memory backing store, even after system shutdown. This paper proposes new approach for adding multilevel security capability to virtual memory management. It uses partial swap encryption based on process’s security policy. Volatile encryption keys are chosen randomly, and remain valid only for short time periods. Performance comparison shows the total overhead of proposed method.

1. The Natural Numbers. The Basics. The Fundamental Theorem of Arithmetic. Searching for Primes. Number Fascinations. 2. The Integers. Diophantine Equations. Congruence Arithmetic. Pell and Pythagoras. Factoring Large Numbers. 3. The Rational Numbers. Rational Numbers as Decimals. Decimals as Rational Numbers. Continued Fractions. Solving Equations on the Rational Plane 4. The Real Numbers. Algebraic Representations. Geometric Representations. Analytic Representations. Searching for Transcendental Numbers. 5. Mathematical Projects. Rings of Factors. Sums of Consecutive Numbers. Measuring Abundance. Inside the Fibonacci Numbers. Pictures at an Iteration. Eenie Meenie Miney Mo. Factoring with the Pollard ...r Method. Charting the Integral Universe. Triangles on the Integral Lattice. The Gaussian Integers. Writing Fractions the Egyptian Way. Building Polygons with Dots. The Decimal Universe of Fractions, I. The Decimal Universe of Fractions, II. The Making of a Star. Making Your Own Real Numbers. Building 1 the Egyptian Way. Continued Fraction Expansions of x1/2 N. A Special Kind of Triangle. Polygon Numbers. Continued Fraction Expansions.

In this paper, a variety of cloud service combinations is used to form the control core of a smart home, realize data forwarding, storage, and analysis in the cloud, and complete the remote management of smart home devices. This paper studies the secure access control of smart home data combined with the blockchain technology and password technology to realize the secure and efficient access control of smart home data. The system can achieve the goal of independent research and development. Aiming at the problem that the access control of a smart home is generally managed by third‐party authorized institutions and there is an unauthorized access, a blockchain‐based smart home (BSH) access control scheme is proposed. The scheme extends the attribute‐based access control model (ABAC) and applies the blockchain technology to the smart home ABAC model to realize fine‐grained access control. In the scheme, the resource provider first publishes the access control policy of the resource to the blockchain. If the resource visitor wants to access the resource, he needs to submit an access request to the blockchain and use an SM2 threshold signature to process the transaction proposal. The endorsement peer node in the blockchain runs the access control policy smart contract to decide whether to grant access rights. This scheme can ensure that resource providers can participate in all the processes of access control and avoid the risk of unauthorized access caused by the centralized management of the third party. Finally, the simulation experiment is carried out on the Hyperledger Fabric alliance chain development platform. The results show that the BSH access control scheme has good applicability in the smart home scenario.

An access control scheme based on Chinese remainder theorem and time stamp concept