Patent ID: 8683552

Claim:
A terminal device that delivers information to another terminal device, comprising: a condition storage unit that stores a primary delivery condition relating to whether delivery of information to a terminal device of a primary delivery destination is prohibited or permitted; a trustability storage unit that stores a delivery destination trustability value that indicates a degree of trust in a user who is an owner of the terminal device of the primary delivery destination, the delivery destination trustability value being kept confidential; a judgment unit that judges whether or not to deliver the information to the terminal device of the primary delivery destination, by using the primary delivery condition; a generation unit that generates, when the judgment unit judges to deliver the information, a secondary delivery condition by performing a calculation using the delivery destination trustability value based on the primary delivery condition, the secondary delivery condition relating to whether delivery of the information from the terminal device of the primary delivery destination to a terminal device of a secondary delivery destination is prohibited or permitted; and a sending unit that sends the generated secondary delivery condition to the terminal device of the primary delivery destination without sending the delivery destination trustability value, wherein the primary delivery condition stored in the condition storage unit includes a trustability threshold value that defines a boundary between prohibition and permission of the delivery of the information according to the degree of trust in a user who is an owner of the terminal device of the primary delivery destination, and the generation unit calculates the secondary delivery condition by dividing the trustability threshold value by a value obtained by raising the delivery destination trustability value to a power of a, where a is an integer of one or greater.