Importance

Loading Importance Indicators...

Abstract

A secure information storage system in which a directory stores identifying titles and pointers to areas of a memory storing respective messages. To protect the messages against unauthorized changes, a MAC (message authentication code) is calculated for them in known manner and stored in a register in a secure unit. This involves processing the whole of each message every time the MAC is checked or, if a message has been changed, a fresh MAC has to be calculated. To avoid this, a separate MAC is calculated for each message and stored in the directory, and a global MAC is calculated for the individual MAC's (treating them as if they were a message) and stored in a secure register. To check a stored message, the global MAC is recalculated (thus verifying the MAC of the message), and the MAC of the message is recalculated (thus verifying the message). If the message is changed, its new MAC and a new global MAC are calculated. The system can be extended to a hierarchy of sub-global MAC's.

Loading the Abstract Image...

First Claim