Read-abortion (RA) based synchronization protocols to prevent illegal information flow

• We propose RA-RBS and RA-OBS protocols.
• More than half of read operations are illegal without information flow control.
• No illegal information flow occur but some transactions are aborted in the protocols.
• The abortion ratio in the RA-OBS protocol is smaller than the RA-RBS protocol.

In information systems, data in an object may illegally flow into another object through manipulations of the objects. First, we define a legal information flow relation ri⇒rjri⇒rj among roles riri and rjrj. It means, if a subject granted the role riri manipulates objects before another subject granted the role rjrj, no illegal information flow occur. We discuss safe systems where no illegal information flow occur even if operations from different subjects are performed in any order. Then, we discuss a read-abortion role-based synchronization (RA-RBS) protocol and a read-abortion object-based synchronization (RA-OBS) protocol to prevent illegal information flow in unsafe systems. Here, a transaction is aborted if the transaction reads an object and illegal information flow might occur. We evaluate the RA-RBS and RA-OBS protocols in terms of number of transactions aborted.