Using Trust for Restricted Delegation in Grid Environments

Delegation is an important tool for authorization in large distributed environments. However, current delegation mechanisms used in emerging Grids have problems to allow for flexible and secure delegation. This paper presents a framework to realize restricted delegation using a specific attribute certificate with trust value in grid environments. The framework employs attribute certificates to convey rights separately from identity certificates used for authentication, and enables chained delegations by using attribute certificate chains. In the framework the verifier can enforce securely authorization with delegation by checking the trust values of AC chains, and judge if a delegation is a trusted delegation by evaluating the reputation value of the delegation chain. The paper discusses the way of computing trust and reputation for delegation, and describes some details of delegation, including the creation of delegation credential and the chained delegation protocol.