Shigenari Nakamura

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In information systems, data in an object may illegally flow into another object if a subject manipulates the objects. In this paper, we discuss information flow control models to prevent illegal information to occur in the role-based access control (RBAC) model. First, we define a legal information flow relation r<sub>i</sub>&#x21D2; r<sub>j</sub> among(More)
Information systems have to be secure in presence of illegal access. A transaction illegally reads an object if the transaction reads the object which includes data in other objects which is not allowed to be read. A transaction illegally writes an object after illegally reading some object. In addition, we consider suspicious object whose data is not(More)
In information systems, data in an object may illegally flow into another object if transactions manipulate the objects. In our previous studies, the role-based synchronization (RBS) and object-based synchronization (OBS) protocols are discussed to present illegal information flow in the role-based access control (RBAC) model. Illegal read operations mean(More)
In information systems, data in an object may illegally flow into another object if transactions read and write the objects. A transaction illegally reads an object if data in objects which the transaction is not allowed to read are stored in the object. In addition, it is specified data in which object is allowed to flow to other objects. A suspicious(More)
In information systems, objects have to be not only legally accessed in presence of illegal accesses but also data in a suspicious object is not allowed to flow to another object. A transaction illegally and suspiciously reads an object if the transaction reads the object which includes data in other objects which are not allowed to be read and the object(More)
Information systems are getting scalable like cloud computing systems and Internet of Things (IoT). It is critical to reduce electric energy consumed in our society. In information systems, we have to reduce the electric energy consumed by computers, especially servers in clusters to perform application processes. Types of application processes like(More)
Application processes have to be efficiently performed in presence of server faults in a cluster. Multiple replicas of a process are performed on multiple servers. However, the more number of replicas of a process are performed, the more reliable and available the process can be performed but the more amount of electric energy is consumed. In this paper, we(More)
In information systems, illegal information flow among objects has to be prevented. A transaction illegally and suspiciously reads an object if the object includes data in other objects which are not allowed to be read and the object is suspicious, respectively. A transaction illegally and impossibly writes an object after illegally and suspiciously reading(More)