In new distributed, key-oriented access control systems such as SPKI, access right are delegated by a freely formed network of certificates. We formalize the concept of a delegation network and present a formal semantics for the delegation of access rights with certificates. The certificates can have multiple subjects who must co-operate to use the authority. Some fundamental properties of the ...

The concept of literacy has undergone a conceptual leap due to the constant growth of technology and the introduction of digital tools. Often-cited as an important component of modern literacy, digital literacy has received significant attention. Since the role of socio-demographic characteristics like gender, place of residence, access to digital tools, fields of study, level of university and...

In this paper we present a non-transferable anonymous credential system that is based on the concept of a chameleon certificate. A chameleon certificate is a special certificate that enjoys two interesting properties. Firstly, the owner can choose which attributes of the certificate to disclose. Moreover, a chameleon certificate is multi-show in the sense that several uses of the same chameleon...

The development of Public Key Infrastructures (PKIs) is highly desirable to support secure digital transactions and communications throughout existing networks. It is important to adopt a particular trust structure or PKI model at an early stage as this forms a basis for the PKI’s development. Many PKI models have been proposed but use only natural language descriptions. We apply a simple forma...

This paper extends the certificateless public key infrastructure model that was proposed by Hassouna et al by proposing new digital signature scheme to provide true non-repudiation, the proposed signature scheme is short and efficient, it is also has strength point that the KGC has no contribution in signature generation/verification process, therefore any compromise of the KGC does not affect ...

In this note we consider how role-based access control can be managed on a large scale over the Internet and across organizational boundaries. We take a PKI approach, in which users are identified using public key certificates, as are the servers. The main features of our approach are: access control by (client, role) pair; implied revocation based on the role hierarchy; automatic generation of...

A microcomputer-based simulator for digital control systems is proposed. The proposed simulator is a hybrid system in which the plant is simulated by conventional method of analog computers and other parts of the system including generation of input signal is performed digitally, using a Z-80 based microcomputer. To overcome the difficulty of programming in assembly language, and at the same ti...

1 Introduction The revolutionary advances in computer technology today have made it possible to replace conventional controllers with digital computers. Digital control thus refers to the control scheme in which the controller is a digital device, practically a digital computer. This means that we can make use of a much more advanced control logic and versatility than those made possible with c...

Recording the variation of joint angles as a feedback to the control unit is frequent in articulated arms. In this paper, magnetic sensor AS5045, which is a contactless encoder, is employed to measure joint angles of 6R robot and the performance of that is examined. The sensor has a low volume, two digital outputs and provides a high resolution measurement for users; furthermore its zero positi...