Patent ID: 7937584

Claim:
A method for key certification in a public key infrastructure, said public key infrastructure having a node network formed of a plurality of nodes that comprises a first entity node and a first global root node, said method comprising: providing a first root public key for a first user by a first means outside the public key infrastructure, said first root public key being at the first global root node, wherein each pair of adjacent nodes of the plurality of nodes consists of a first node and second node such that the first node is configured to provide a digital certificate for certifying the second node and the second node is configured to provide a digital certificate for certifying the first node; and providing a first chain of digital certificates in a first nodal path from the first global root node across the node network to a first entity node, wherein the first chain of digital certificates enables the first user to verify a public key of the first entity node; wherein the plurality of nodes consists of a plurality of computer nodes; wherein the nodes of the plurality of nodes are trusted authorities arranged in a hierarchy having L levels denoted as levels 1 , 2 , 3 . . . . L subject to L being at least 3; wherein level 1 consists of a highest node of the hierarchy; wherein level j consists of at least two nodes of the hierarchy, each node of level j being a child node of level j-1 for j =2, 3. . . . L; wherein level 3 consists of at least three nodes of the hierarchy; wherein the first entity node is a node of a level of at least 3 and not exceeding L; wherein the first global root node is a selected node of level 2 ; wherein the method further comprises prior to said providing the first root public key for the first user and prior to said providing the first chain of digital certificates: arranging a common liability agreement among the nodes of level 2 by which the nodes of level 2 agree to accept liability to any user who selects a node of level 2 as a global root node in a chain of digital certificates for verifying a public key of any other node of the hierarchy, said arranging being performed by the highest node of the hierarchy; and after said arranging, receiving an identification from the user of the first global root node after the user selected the first global root node as the selected node of level 2 .