A flexible read-write abortion protocol with role safety concept to prevent illegal information flow

摘要

In information systems, illegal information flow among objects has to be prevented. A transaction illegally reads data in an object if the object includes data in other objects which are not allowed to be read. In our previous studies, the FRWA-R (flexible read-write-abortion with role sensitivity) and FRWA-O (object sensitivity) protocols are proposed to prevent illegal information flow. Here, a transaction aborts with some probability once illegally reading data in an object. The abortion probability depends on the sensitivity of roles which the transaction holds and objects in which the transaction illegally reads data. The role sensitivity and object sensitivity show how many transactions which hold the role and illegally read data in the object abort after illegally reading data in the object, respectively. Here, the sensitivity just monotonically increases each time a transaction aborts. In this paper, we propose a new safety concept of a role and an FRWA-RS (FRWA with role safety) protocol. Here, the safety of a role increases and decreases each time a transaction holding the role commits and aborts by issuing an illegal read operation, respectively. A transaction with safer roles aborts with smaller probability. In the evaluation, we show fewer and more numbers of transactions abort in the FRWA-RS protocol than the RWA protocol and than the WA protocol, respectively, and transactions are more efficiently performed than the WA protocol.