Abstract: An authentication device includes an authentication unit, a history information generator and a communication unit. The authentication unit executes, when a user terminal accesses a service provider system, an authentication process based on an authentication request that includes a description pertaining to an authentication condition and an authentication method that correspond to the service provider system. The history information generator generates history information. The history information includes information indicating whether the authentication condition is satisfied and information indicating a result of executing the authentication process by using the authentication method. The communication unit transmits the history information to the user terminal.

Abstract: A communication device among a plurality of communication devices is used in a distributed computing system. The distributed computing system executes a target process including a plurality of partial processes by using the plurality of communication devices. The communication device includes a memory and a processor. The memory stores a trail that represents a state of the plurality of partial processes. The processor selects, from among the plurality of partial processes, an uncompleted partial process with a number of equivalent execution results being less than a target number according to the trail. The processor executes the uncompleted partial process selected by the selector. The processor records an execution result obtained by the execution unit in the trail.

Abstract: A non-transitory computer-readable storage medium storing a program that causes a processor included in a communication apparatus to execute a process, the process includes issuing a credential that is used by a user of another communication apparatus; storing identification information of the credential in association with a second key that is usable for decrypting information encrypted with a first key that is used by the another communication apparatus for encryption; and when signature information attached to an inquiry message inquiring whether a credential identified by the identification information is valid is decryptable with the second key, transmitting information representing whether the credential identified by the identification information is valid to the another communication apparatus.

Abstract: An information processing device provides a function of a first agent corresponding to a first entity in a communication system in which a plurality of agents respectively manage attribute information of corresponding entities. The information processing device includes: a processor; and a memory configured to store attribute information that indicates an attribute of the first entity. The processor decides whether the attribute information includes information relating to a third entity when the information processing device receives an attribute request from a second agent corresponding to a second entity. The processor edits the attribute information based on a policy of the third entity with respect to a disclosure of the information relating to the third entity when the attribute information includes the information relating to the third entity. The processor transmits the edited attribute information to the second agent.

Abstract: A communication device among a plurality of communication devices is used in a distributed computing system. The distributed computing system executes a target process including a plurality of partial processes by using the plurality of communication devices. The communication device includes a memory and a processor. The memory stores a trail that represents a state of the plurality of partial processes. The processor selects, from among the plurality of partial processes, an uncompleted partial process with a number of equivalent execution results being less than a target number according to the trail. The processor executes the uncompleted partial process selected by the selector. The processor records an execution result obtained by the execution unit in the trail.