Information processing device, method for controlling information processing device, and non-transitory computer readable medium

A method for controlling an information processing device,

• the information processing device comprising:
• a memory;
• an authentication tree cache in which some of counters, identifiers, and tags generated by using the counters and the identifiers, are temporarily stored, the counters and the identifiers being included in an authentication tree including a plurality of nodes connected with one another in a tree shape in which a pair of a counter and an identifier is assigned to each of the nodes;
• a data cache in which some of a plurality of data respectively assigned to a plurality of leaf nodes are temporarily stored, the plurality of leaf nodes being nodes located in a lowest layer among the plurality of nodes constituting the authentication tree;
• and
• an authenticated memory encryption engine configured to perform a cryptographic process and an authentication process using the authentication tree for data to be exchanged between the data cache and the memory, and perform an authentication process for at least one tag respectively generated at at least one node present on a path from a leaf node to which the data is assigned to a root node,
• the method comprising:
• updating, when any of the plurality of nodes constituting the authentication tree is to be deleted, a value of a counter assigned to a parent node of the node to be deleted based on a value of a counter assigned to the node to be deleted;
• and
• setting, when a new node is to be added at a position where the deleted node was originally located in the authentication tree, a value of a counter assigned to the added node to a value different from the value of the counter assigned to the node to be deleted based on a value of a counter assigned to a parent node of the added node.

A non-transitory computer readable medium storing a control program for causing a computer to perform a process for controlling an information processing device,

• the information processing device comprising:
• a memory;
• an authentication tree cache in which some of counters, identifiers, and tags generated by using the counters and the identifiers, are temporarily stored, the counters and the identifiers being included in an authentication tree including a plurality of nodes connected with one another in a tree shape in which a pair of a counter and an identifier is assigned to each of the nodes;
• a data cache in which some of a plurality of data respectively assigned to a plurality of leaf nodes are temporarily stored, the plurality of leaf nodes being nodes located in a lowest layer among the plurality of nodes constituting the authentication tree;
• and
• an authenticated memory encryption engine configured to perform a cryptographic process and an authentication process using the authentication tree for data to be exchanged between the data cache and the memory, and perform an authentication process for at least one tag respectively generated at at least one node present on a path from a leaf node to which the data is assigned to a root node,
• the control program being configured to further cause the computer to perform:
• a process for updating, when any of the plurality of nodes constituting the authentication tree is to be deleted, a value of a counter assigned to a parent node of the node to be deleted based on a value of a counter assigned to the node to be deleted;
• and
• a process for setting, when a new node is to be added at a position where the deleted node was originally located in the authentication tree, a value of a counter assigned to the added node to a value different from the value of the counter assigned to the node to be deleted based on a value of a counter assigned to a parent node of the added node.