Information verification system, information verification device, method and program

At least one of nodes included in the second node group comprises a request means (521) for transmitting a request signal including verification information to at least any node of the first node group, and a verification means (522) for verifying response information for the request signal, the verification means determines, regarding the response information, whether or not desired information that is information requested by the request signal or a digest thereof is included, whether or not correct verification information is included, whether or not a value obtained by applying a one-way function to the response information satisfies a predetermined rule, and a response time that is the time taken between the transmission of the request signal and the obtainment of the desired information, and on the basis of the determination results thereof, assesses the presence or absence of reliability of the desired information or the degree of reliability thereof.