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

Parallel manipulators with less than six degrees of freedom (DOF) have been increasingly used in high-speed hybrid machine tools. The structural features of parallel manipulators are dynamic, a characteristic that is particularly significant when these manipulators are used in high-speed machine tools. However, normal kinematic control method cannot satisfy the requirements of the control system. Many researchers use model-based dynamic control methods, such as the dynamic feedforward control method. However, these methods are rarely used in hybrid machine tools because of the complex dynamic model of the parallel manipulator. In order to study the dynamic control method of parallel manipulators, the dynamic feedforward control method is used in the dynamic control system of a 3-PSP (prismatic-spherical-prismatic) 3-DOF spatial parallel manipulator used as a spindle head in a high-speed hybrid machine tool. Using kinematic analysis as basis and the Newton-Euler method, we derive the dynamic model of the parallel manipulator. Furthermore, a model-based dynamic feedforward control system consisting of both kinematic control and dynamic control subsystems is established. The dynamic control subsystem consists of two modules. One is used to eliminate the influence of the dynamic characteristics of high-speed movement, and the other is used to eliminate the dynamic disturbances in the milling process. Finally, the simulation model of the dynamic feedforward control system of the 3-PSP parallel manipulator is constructed in Matlab/Simulink. The simulations of the control system eliminating the influence of the dynamic characteristics and dynamic disturbances are conducted. A comparative study between the simulations and the normal kinematic control method is also presented.The simulations prove that the dynamic feedforward control method effectively eliminates the influence of the dynamic disturbances and dynamic characteristics of the parallel manipulator on high-speed machine tools, and significantly improves the trajectory accuracy. This is the first attempt to introduce the dynamic feedfordward control method into the 3-PSP spatial parallel manipulator whose dynamic model is complex and provides a study basis for the real-time dynamic control of the high-speed hybrid machine tools.

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.

Secure and efficient revocable key-aggregate cryptosystem for multiple non-predefined non-disjoint aggregate sets

Security of Platform as a Service for multi-tenant becomes a key factor for the sustainable development of the system. This paper analyzes the limitations and shortcomings of traditional identity authentication. Identity authentication is realized through the ticket authentication method. Considering the dynamic and timeliness of resources in cloud computing, this paper proposes a dynamic access control method based on Role-Based Access Control and usage control model from the perspective of business conversation, so as to realize the dynamic access control of tenants to resources in Platform as a Service. The paper elaborates on the security and usability of the key generation, distribution, update, and metadata access control processes. Practice shows that the cloud resource access control model can flexibly realize the control of cloud resources such as authority separation, resource attribute restriction and utilization control, so as to better meet the demand of cloud resource access control with multi-tenant sharing and dynamic characteristics in cloud environment.

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.

One of the security issues in data outsourcing scenario is the enforcement of data owner's access control policies. This includes some challenges; namely, the number of keys required to access authorized resources, efficient policy updating, write access control enforcement, user and data owner overhead, and preserving confidentiality of data and policies. Most of the existing solutions address only some of the challenges, while they impose high overhead on both the data owner and users. Though, policy management in the Role-Based Access Control (RBAC) model is easier and more efficient due to the existence of role hierarchical structure and role inheritance; most of the existing solutions address only enforcement of policies in form of access control matrix. In this paper, we propose an approach to enforce RBAC policies on encrypted data outsourced to service provider (SP). We utilize Chinese Remainder Theorem (CRT) for key management and role/permission assignment. Efficient user revocation, support of role hierarchical structure updates, availability of authorized resources for users of newly added roles, and enforcement of write access control policies as well as static separation of duties (SSD), are of the proposed solution advantages. In addition, the ciphertext size is linearly proportional to the plaintext size, regardless of the number of roles and users.

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.

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.

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.

Security of Computer Networks

The American National Standards Institute (ANSI) has standardized an access control approach, Next Generation Access Control (NGAC), that enables simultaneous instantiation of multiple access control policies. For large complex enterprises this is critical to limiting the authorized access of insiders. However, the specifications describe the required access control capabilities but not the related algorithms. While appropriate, this leave open the important question as to whether or not NGAC is scalable. Existing cubic reference implementations indicate that it does not. For example, the primary NGAC reference implementation took several minutes to simply display the set of files accessible to a user on a moderately sized system. To solve this problem we provide an efficient access control decision algorithm, reducing the overall complexity from cubic to linear. Our other major contribution is to provide a novel mechanism for administrators and users to review allowed access rights. We provide an interface that appears to be a simple file directory hierarchy but in reality is an automatically generated structure abstracted from the underlying access control graph that works with any set of simultaneously instantiated access control policies. Our work thus provides the first efficient implementation of NGAC while enabling user privilege review through a novel visualization approach. These capabilities help limit insider access to information (and thereby limit information leakage) by enabling the efficient simultaneous instantiation of multiple access control policies.

One of the critical requirement in managing security of any computing system is access control, which includes protection and access management to the available resources. This requirement becomes more strict especially in a distributed computing environment that consists of constrained devices such as Machine-to-Machine (M2M). New challenges in access control are identified in a system comprises a group of distributed multiple M2M gateways forming a so called M2M local cloud platform (Vallati et al. in Wirel Trans Commun 87(3):1071–1091, 2016). Scalability is obviously a necessity which is lacking in some existing access control system. In addition, flexibility in managing access from users or entity belonging to other authorization domains as well as delegating access right are not provided as an integrated features. Lately, the capability-based access control has been suggested as method to manage access for M2M as the key enabler of Internet of Things. In this paper, a capability based access control equipped with Elliptic Curve Cryptography based key management is proposed for the M2M local cloud platform. The feasibility of the proposed capability based access control and key management are tested by implementing them within the security manager that is part of the overall component of the platform architecture, and evaluating their performances by a series of experimentations.

The standard ACE framework provides authentication and authorization mechanisms similar to those of the standard OAuth 2.0 framework, but it is intended for use in Internet-of-Things environments. In particular, ACE relies on OAuth 2.0, CoAP, CBOR, and COSE as its core building blocks. In ACE, a non-constrained entity called Authorization Server issues Access Tokens to Clients according to some access control and policy evaluation mechanism. An Access Token is then consumed by a Resource Server, which verifies the Access Token and lets the Client accordingly access a protected resource it hosts. Access Tokens have a validity which is limited over time, but they can also be revoked by the Authorization Server before they expire. In this work, we propose the Usage Control framework as an underlying access control means for the ACE Authorization Server, and we assess its performance in terms of time required to issue and revoke Access Tokens. Moreover, we implement and evaluate a method relying on the Observe extension for CoAP, which allows to notify Clients and Resource Servers about revoked Access Tokens. Through results obtained in a real testbed, we show how this method reduces the duration of illegitimate access to protected resources following the revocation of an Access Token, as well as the time spent by Clients and Resource Servers to learn about their Access Tokens being revoked.

SNMPv3 (D. Partain et al., 1999; R. Presuhn et al., 1999), supports authentication, confidentiality and access control. Access control is based on MIB views, which makes it possible to have fine grained control over who accesses what in a MIB. Different users can be given different access rights. However, as the number of users increase, it becomes very difficult to keep control over all the different access rights. The paper describes a new graphical language called MIB View Modeling Language that provides a tool for easy specification of MTB views. It is a hierarchical language that provides mechanisms for supporting a large number of different users and MIB views.

To avoid too strong a trust on any single user in sensitive applications, access control can be managed in a distributed way. Namely, an access right is distributed among multiple users such that the access is available if and only if certain subsets of the users cooperate. The most common condition for qualified subsets is the threshold condition, which requires that the number of cooperating users must be over a threshold. Access control based on such a condition is called TDAC (threshold distributed access control). In publicly verifiable applications, TDAC must provide public verification such that it is publicly verifiable that the multiple users share the correct access right and any qualified subset of them can obtain the access. Although the existing PVSS (publicly verifiable secret sharing) techniques can be employed to implement PVTDAC (publicly verifiable TDAC), they are not efficient enough for practical applications. In this paper, new sharing and proof techniques are proposed to design an efficient PVTDAC protocol, which is formally illustrated to be secure and publicly verifiable.