Abstract: A control method includes: selecting one or more first transaction data items to be stored in a block, from a plurality of transaction data items stored in a pool area in a memory; and determining a difficulty of mining to be executed at a time of storing the one or more first transaction data items in a first blockchain, based on values of one or more first data items included in the one or more first transaction data items selected.

Abstract: A malware detection method for a home network system including one or more home appliances that are connected to a home network includes: obtaining a plurality of setting values including at least information indicating a device type and an operating state of a target device subject to malware detection; selecting one detection model out of a plurality of detection models according to the plurality of setting values obtained; obtaining power consumption or current consumption of the target device; and detecting whether the target device is infected with malware, based on stable power or stable current obtained in the obtaining of the power consumption or the current consumption using the one detection model selected in the selecting, when the power consumption indicates stable power that varies within a predetermined range or the current consumption indicates stable current that varies within a predetermined range.

Abstract: A control method according to the present disclosure is performed by one of a plurality of servers each including a distributed ledger and includes: obtaining request transaction data including an analysis request identification (ID) uniquely identifying a request for analysis, and an access method for accessing relevant information usable for the analysis; and recording a block including the request transaction data into the distributed ledger.

Abstract: A secure authentication method includes: deriving a distributed LSH value using secret LSH, taking a first distributed feature amount which is a feature amount of user information distributed through a secret distribution method and encrypted LSH parameters as inputs; deriving a distributed hash value using a secret unidirectional function, taking the distributed LSH value and a distributed key as inputs; decoding the hash value by reversing distribution of the distributed hash value; selecting, from a secret hash table storing sets of a hash value as an index and a distributed feature amount as a data string, a set including a hash value matching the decoded hash value; computing, in secret, similarity between the distributed feature amount in the set and the first distributed feature amount; deriving, in secret, a user authentication result based on the similarity computed; and outputting the derived authentication result.

Abstract: A control method according to the present disclosure includes: determining the presence or absence of transaction data related to a first target that has not been used for a predetermined period among targets each being transaction data stored in a blockchain; and deleting the transaction data related to the first target from the blockchain based on a determination result indicating that the transaction data related to the first target is present.

Abstract: A fault monitoring method is executed by a monitoring device in a fault monitoring system that includes a terminal used by a user, an appliance to be operated by the user, the monitoring device, and a plurality of authentication servers each including a distributed ledger, and includes: obtaining event information stored in the plurality of authentication servers and indicating an event generated in response to a request that includes a processing instruction for the user operating the appliance; obtaining state information indicating whether the appliance is faulty, from the appliance; generating first transaction data including the state information obtained and transmitting the first transaction data to the plurality of authentication servers; and transmitting the processing instruction included in the event information to the appliance, when the appliance is determined to be not faulty from the state information.

Abstract: A control method includes: receiving first information pertaining to a first contract from a first terminal used by a first user who is one of two parties who have agreed to the first contract; when consent of a party aside from the two parties is required to validate the first contract, identifying a second user as the party aside from the two parties with reference to a ledger storing information pertaining to a past contract, and transmitting the first information to a second terminal operated by the second user; obtaining second information in which a confirmation result indicating whether the second user consents to the first contract and a digital signature of the second user are added to the first information; and confirming the second information, and when the confirmation result indicates consent, setting the first contract as a valid contract and storing the second information in the ledger.

Abstract: A malware detection method for a home network system including one or more home appliances that are connected to a home network includes: obtaining a plurality of setting values including at least information indicating a device type and an operating state of a target device subject to malware detection; selecting one detection model out of a plurality of detection models according to the plurality of setting values obtained; obtaining power consumption or current consumption of the target device; and detecting whether the target device is infected with malware, based on stable power or stable current obtained in the obtaining of the power consumption or the current consumption using the one detection model selected in the selecting, when the power consumption indicates stable power that varies within a predetermined range or the current consumption indicates stable current that varies within a predetermined range.

Abstract: A malware detection method for a home network system including one or more home appliances that are connected to a home network includes: obtaining a plurality of setting values including at least information indicating a device type and an operating state of a target device subject to malware detection; selecting one detection model out of a plurality of detection models according to the plurality of setting values obtained; obtaining power consumption or current consumption of the target device; and detecting whether the target device is infected with malware, using the one detection model selected in the selecting and based on the power consumption or the current consumption obtained.

Abstract: A control method in which each of an Internet of things (IoT) device and a user who uses the IoT device has a digital account includes: obtaining first transaction data for allowing the user who used the IoT device to transfer a first amount corresponding to a usage amount of the IoT device; specifying, from the first transaction data obtained, the digital account of the IoT device that is associated with an identifier uniquely assigned to hardware of the IoT device; and transferring the usage amount of the IoT device to the digital account of the IoT device by deducting the first amount from the digital account of the user and adding the first amount to the digital account of the IoT device based on the first transaction data obtained.

Abstract: A method includes: acquiring transaction data that includes value information regarding a value to be transferred from a second user to a first user; executing a first smart contract recorded in a first blockchain by recording the transaction data in the first blockchain; and executing a second smart contract recorded in a second blockchain different from the first blockchain based on the first smart contract. The second smart contract is a smart contract for transferring at least a portion of the value to be transferred from the second user to the first user, from a first account held by the first user to a third account held by a third user.

Abstract: An authentication server acquires and stores first transaction data in a distributed ledger, the first transaction data indicating a transfer of a first amount as a remaining transfer amount from a first account of a first user to a second account of a second user, and executes a first program. When the first amount is greater than a second amount indicating a balance in the first account, the first program transfers the second amount to the second account. The authentication server acquires and stores second transaction data in the distributed ledger, the second transaction data indicating a transfer of a fourth amount from a third account of a third user to the first account, and executes a second program. The second program transfers the fourth amount from the third account to the first account, and the first program transfers all or part of the fourth amount to the second account.

Abstract: A control method that is performed by a device in a distributed ledger system including a plurality of nodes each holding a distributed ledger includes: obtaining transaction data to be stored into the distributed ledger; obtaining a security level of each of the plurality of nodes; and preferentially determining a node having a higher security level among the plurality of nodes as a destination node for the transaction data.

Abstract: An electric lock control method includes: performing a first determination of whether a person is present in a predetermined region surrounding an electric lock, based on first information generated by an electronic device; when it is determined that a first person is present in the predetermined region in the performing of the first determination, performing a second determination of whether the first person is a person who is permitted to unlock the electric lock, based on second information related to movement of the first person; and controlling a state of the electric lock based on a result of the second determination, the state being a locked state or an unlocked state.

Abstract: A control method that is performed by a first device included in a plurality of devices includes: receiving, from a terminal being used by a second user, first transaction data indicating that value information is to be transferred from a first user to the second user; and storing the received first transaction data into a distributed ledger.

Abstract: A method includes: transmitting, to a second device used by a second user, identification information of a smart contract including a process of providing content according to a provision condition under which a first user allows to provide the content, through short-range wireless communication; receiving transaction data including identification information of the second device and instruction information for instructing to execute the smart contract, through short-range wireless communication; and storing the transaction data received in a distributed ledger and executing the smart contract, to change an owner of the content from the first user to the second user.

Abstract: A control method to be executed by a first device includes: receiving identification information identifying a second device from the second device by near-field communication; determining an evaluation value indicating appropriateness of the processing executed by the second device, with reference to a storage device that stores history information indicating processing executed by the second device; and restricting the near-field communication with the second device, based on the evaluation value determined.

Abstract: A control method according to the present disclosure is a method for controlling a first terminal carried by a first user and capable of communicating with a server via a network and includes: establishing short-range wireless communication by the first terminal with a second terminal carried by a second user; requesting the second terminal by the first terminal via the short-range wireless communication to provide item information, which is information related to at least one item included in one or more items worn by the second user, or requesting the server by the first terminal via the network to provide the item information, using identification information of at least one item that has been obtained upon the establishment of the short-range wireless communication; obtaining the item information by the first terminal; and transmitting, to the server, item positive-obtainment information indicating that the item information has been obtained.

Abstract: A control method according to the present disclosure is a method for controlling an information spot placed on at least one of a traffic light and roadside equipment and includes: obtaining, from a first mobile body via short-range wireless communication, first information obtained from a first path along which the first mobile body has traveled to reach the location of the information spot and indicating a situation on the first path; obtaining information related to the destination of a second mobile body, which is different from the first mobile body, from the second mobile body via the short-range wireless communication; and transmitting the first information to the second mobile body when it is determined that the second mobile body is to travel along at least a part of the first path to reach the destination.

Abstract: A control method for a first moving body includes: acquiring, from a second moving body, emergency information that includes information on a scheduled route on which an emergency vehicle travels in an emergency; and transmitting, by device-to-device communication, the emergency information to a third moving body that is predicted to travel on the scheduled route.