Patent ID: 7237107

Claim:
A method for discovering a trust chain, wherein the trust chain comprises at least attribute delegations each with an issuer and a subject, overall imparts a required attribute to a subject, and is grounded in a known trusted issuer, and wherein certificates are used as justification of associated attribute delegations, the method comprising: a) setting as a primary goal to be proved an attribute delegation from a known trusted issuer to said subject; b) seeking a backwards proof of said primary goal by a process of recursively taking a goal to be proved, starting with said primary goal, and decomposing it into subgoals one of which corresponds to an attribute delegation that is justified by an available certificate and has the same subject as the goal being decomposed, inability to decompose a subgoal that has not been proved causing the process to backtrack to a previous subgoal to seek a new decomposition of the latter; and c) determining that a trust chain has been found upon the process of (b) producing a chain of subgoals that is proved by corresponding certificates and that grounds in a subgoal justified by a justified attribute delegation that has as issuer the said known trusted issuer included in said primary goal.