Patent ID: 8055589

Claim:
A traceability verifying method for using a certificate issued by a certificate authority device to trace a supply chain by means of a signature chain, wherein in the supply chain a deliverer receives a supply of parts from disclosed suppliers and undisclosed private suppliers and ships products comprising the parts to at least one third party, the disclosed suppliers being indentified to the third party and the undisclosed private suppliers being unidentified to the third party, the traceability verifying method comprising the steps of: signing said signature chain based on a group certificate issued by said certificate authority device, the group certificate being common to a plurality of undisclosed private suppliers; signing said signature chain based on a first individual certificate of a disclosed supplier selected from said disclosed suppliers; signing said signature chain based on a second individual certificate of a supplier manager after said signature chain is signed based on said group certificate; verifying said signature chain by a computer while maintaining confidentiality of said private suppliers, wherein verifying said signature chain is based on a group public key received from said certificate authority device; and identifying said private suppliers based on a group private key received from said certificate authority device.