Obtaining sufficient information is a significant issue to compute trust about a security system in cyber space. In existing approaches, an entity considers only its experiences about a service and recommendations about the security system of the service. Such approaches are not adequate for critical services in cyber space since trust computations take quite a long time. Determining trust about critical services in a faster manner is a challenging issue. This paper presents a model to increase security experiences about a service by using similarities of security systems. We use security experiences to compute trust. The results of trust computations are used for security interoperability decision making. The case studies and simulations have shown that the proposed model significantly improves security experiences which results in fast and accurate security interoperability decision making. (C) 2013 Elsevier B.V. All rights reserved.