rights to other users at his complete discretion. Grantees can also The semantically rich data models of object-oriented database be permitted to pass a subset of their rights to other users. management systems (OODBMSs) are much more a challenge to While this approach is very flexible and adaptive, there is no achieve security than the traditional (relational) models. Issues to central securit...

Modern operating systems each have different implementations of access controls and use different policies for determining the access that subjects may have on objects. This paper reviews the three main types of access control policies: discretionary, mandatory, and role-based. It then describes how Windows and various Unix systems implement their chosen access control policies. Finally, it dis...

A common definition of computer security is: ” a system is secure if it adequately protects information that it processes against unauthorized disclosure, unauthorized modification, and unauthorized withholding (denial of service).” Currently, no systems can assure all of these. The first major efforts on such a system is the so called mandatory access control (MAC). It is for military security...

Security is a crucial property of system behaviour. It generally requires some kind of control over the information ow among parts of the system. In order to analyze these possible ows it has been introduced the Non-Interference (NI) property 7]. In particular NI was introduced to detect all the possible ows from a group of users to another one. A lot of research has been done about NI in the f...

In software construction, analysis investigates system requirements and design captures system functionality. To facilitate analysis and design, one popular technique is the unified modeling language, UML. In UML, there are use-case diagrams for the interaction of users with system components, class diagrams for the static classes and relations among them, and sequence diagrams for the dynamic ...

 Paid employment determines pension levels, for both women and men. In those European countries in which women have been integrated into the labour market at an early stage their protection in old age is higher today for that reason alone. Germany lags behind in this respect.  Gender-specific differences in the employment participation of the low educated are greater than those between the ed...

Do mandatory spending programs such as Medicare improve efficiency? We analyze a model with two parties allocating a fixed budget to a public good and private transfers each period over an infinite horizon. We compare two institutions that differ in whether public good spending is discretionary or mandatory. We model mandatory spending as an endogenous status quo since it is enacted by law and ...

ESP and AH protocols make use of various cryptographic algorithms to provide confidentiality and/or data origin authentication to protected data communications in the IP Security (IPsec) architecture. To ensure interoperability between disparate implementations, the IPsec standard specifies a set of mandatory-toimplement algorithms. This document specifies the current set of mandatory-to-implem...

As organizations depend on, possibly distributed, information systems for operational, decisional and strategic activities, they are vulnerable to security breaches leading to data theft and unauthorized disclosures even as they gain productivity and efficiency advantages. Though several techniques, such as encryption and digital signatures, are available to protect data when transmitted across...