Patent ID: 11888970
Assignee: MONTAGE ELECTRONICS (SHANGHAI) CO
Field: Digital communication (Electrical engineering)
Classification: CPC H  G | IPC G  H

Claim 12:
13. A method for deriving a key from a basekey built-in a chip, comprising:
performing, by a hardware processor, steps of:
obtaining a basekey built-in the chip and a current version number when the chip starts up and runs read-only boot code;
constructing a oriented tree, each node in the oriented tree corresponds to a version, a topological order number of each node indicates a version number corresponding to the node, the basekey is located at a root node of the oriented tree, a version number of any node is smaller than a version number of its parent node,
wherein the oriented tree adopts at least two different one-way functions,
wherein the oriented tree is a two-dimensional matrix graph,
wherein a first node in each row in the two-dimensional matrix graph comprises a longitudinal sub-node and a transverse sub-node, a last node in each row does not comprise any sub-node, and remaining nodes of the oriented tree each only comprises a transverse sub-node,
wherein nodes in a first column in the two-dimensional matrix graph perform iterations via a first one-way function, and nodes in each row in the two-dimensional matrix graph perform iterations via a second one-way function, and
wherein each topological order number of each node in each row decreases one by one, and the topological order number of the last node in each row is greater tha n that of all nodes on its next row; and
performing iterations on the basekey by visiting the oriented tree in a topological order to obtain a derived key of a current version.