Read-Write Abortion (RWA) Based Synchronization Protocols to Prevent Illegal Information Flow

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 object is an object which is not allowed to flow to some object. A transaction suspiciously reads an object if the object is suspicious. If a transaction T writes an object oj after suspiciously reading an object oi, data in the object oi might flow to the object oj. Here, if information flow from the object oi to the object oj is not allowed, the transaction T impossibly writes the object oi. In our previous studies, the read-abortion (RA) role-based synchronization (RA-RBS) and object-based synchronization (RA-OBS) protocols are discussed where a transaction is aborted if the transaction illegally reads an object. Write-abortion (WA) based protocols WA-RBS and WA-OBS are also proposed based on abortion of transactions illegally and impossibly writing objects in our previous studies. In this paper, we newly propose RWA-RBS and RWA-OBS protocols where a transaction is aborted if the transaction illegally reads an object or impossibly writes an object. We evaluate the RWA-RBS and RWA-OBS protocols in terms of number of transactions aborted. We show the smallest number of transactions are aborted in the WA types of protocols.