A communication device includes circuitry configured to acquire a digital certificate including information associated with a first attribute from a first device coupled to any of a plurality of devices sharing a distributed ledger having recorded therein a correspondence between an attribute of user information included in the digital certificate and a definition of the attribute, receive a request for information associated with a second attribute from a second device coupled to any of the plurality of devices, acquire a first definition associated with the first attribute, and a second definition associated with the second attribute, from any of the plurality of devices, and transmit a digital certificate including information associated with the first attribute to the second device together with a message notifying that the first attribute and the second attribute have the same definition, when the first definition and the second definition match.