Patent ID: 11936772
Assignee: nan
Field: Digital communication (Electrical engineering)
Classification: CPC H | IPC H

Claim 0:
1. A method of symmetric key-based digital signing for content creation, content verification, content inspection, content approval, and gated workflow sequence for supply chain tamper resistance, from a device original equipment manufacturer (OEM) to an end-user facility, including at least a content creator at the OEM, a content loader at the end-user facility, a plurality of content approvers at the end-user facility, a policy manager at the end-user facility, a field manager at the end-user facility, a key distribution service (KDS), a KDS portal for users, a KDS application programming interface for applications executing on a user device or field devices, a first secure channel for two-factor user and device authentication-based creation and retrieval of a plurality of digital signing symmetric keys, a second secure channel for content distribution, a dynamic host configuration protocol (DHCP) server, a domain name system (DNS) server, a content identifier, a content file associated with the content identifier, a signature manifest file associated with the content file, an API key, and an API token associated with the content file, a content consumer field device, and a OEM application on the content consumer field device, the method comprising:
creating, by the content creator, a digital signing key to generate a first signature for the content file;
generating, by the content creator, the signature manifest file containing the first signature for the content file;
sending, by the content creator to a plurality of end-user facilities, the content file and the signature manifest file;
verifying, by the content loader at the end-user facility, the signature for the received content file, creating a digital signing key to generate a second signature for the content file, and extending the signature manifest file, including the first signature, with the second signature;
sending, by the content loader, a notification to a first content approver at the end-user facility;
inspecting, by the first content approver at the end-user facility, the content file using a plurality of external third-party content inspection methods, creating a digital signing key to generate a third signature for the content file, and extending the signature manifest file, including the first and second signatures, with the third signature;
sending, by the first content approver, a notification to a second content approver at the end-user facility, for further inspecting;
sending, by a final content approver, a notification to a policy manager at the end-user facility, to associate the content file with update policies, device types, and device groups;
sending, by the policy manager, a notification to a field manager at the end-user facility, to publish the inspected and approved content file and extended signature manifest file, including the first, second and third signatures, and complete a managed content distribution workflow;
querying, by the OEM application on the content consumer field device, the KDS to check for content update and retrieving a download URL/URIs for a content file and extended signature file associated with the content identifier;
downloading, by the OEM application on the content consumer field device, from the DDS the content file and extended signature manifest file from the retrieved URL/URIs;
verifying, by the OEM application on the content consumer field device, the content file by retrieving digital signing key records from the KDS for the tenant identifiers, group identifiers, and key identity hints in the extended signature manifest file that includes the first, second and third signatures, computing hashes and generating signatures for the content file based on retrieved key record specifications for each of the digital signing keys, and matching the generated signatures for the content file with the corresponding signatures in the extended signature manifest file;
installing, by the OEM application on the content consumer field device, the content file using OEM specific update methods; and
notifying, by the OEM application on the content consumer field device, the KDS of an update status on the content consumer field device for state synchronization with the DDS associated with the KDS.