ing and Refining Authorization in SQL Arnon Rosenthal, Edward Sciore1 Abstract. The SQL standard specifies authorization via a large set of rather opaque rules, which are difficult to understand and dangerous to change. To make the model easier to work with, we formalize the implicit principles behind The SQL standard specifies authorization via a large set of rather opaque rules, which are dif...

ÐDigital Libraries (DLs) introduce several challenging requirements with respect to the formulation, specification, and enforcement of adequate data protection policies. Unlike conventional database environments, a DL environment typically is characterized by dynamic user population, often making accesses from remote locations, and by an extraordinarily large amount of multimedia information, s...

In mediated information systems clients and various autonomous sources are brought together by mediators. The mediation paradigm needs powerful and expressive security mechanisms considering the dynamics and conflicting interests of the mediation participants. Firstly, we discuss the security requirements for mediation with an emphasis on confidentiality and authenticity. We argue for basing th...

Policy evaluation is a process to determine whether a request submitted by a user satisfies the access control policies defined by an organization. Modality conflict is one of the main issues in policy evaluation. Existing modality conflict detection approaches do not consider complex condition attributes such as spatial and temporal constraints. An effective authorization propagation rule is n...

Role-Based Access Control (RBAC) has become a popular technique for security purposes with increasing accessibility of information and data, especially in large-scale enterprise environments. However, authorization management in dynamic and ad-hoc collaborations between different groups or domains in these environments is still an unresolved problem. Traditional RBAC models cannot solve this pr...

The authorization problem is to decide whether, according to a security policy, some principal should be allowed access to a resource. In the trustmanagement system SPKI/SDSI, the security policy is given by a set of certificates, and proofs of authorization take the form of certificate chains. The certificate-chain-discovery problem is to discover a proof of authorization for a given request. ...