Post-Manufacture Device Certificate Generation for IoT Security
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Solution Overview
Problem
The existing manufacturing techniques for electronic devices, especially low-cost and low-power devices like IoT sensors, incur increased costs and time due to the need for on-factory generation of public key infrastructure (PKI) key pairs and certificates, which is not justified for all types of devices.
Innovation Solution
A method for post-manufacture generation of device certificates and keys, where a first key associated with the electronic device is used to derive a second key for generating a device certificate and private key, with the certificate generated at a separate certificate generating apparatus and the private key generated on the device, allowing for disjoint and asynchronous key pair generation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If PKI key pairs and certificates are generated during factory manufacturing, then device security and trust verification are ensured, but manufacturing time and costs increase
Solution Approach 1:
A seed key is embedded in the device during manufacturing as a preliminary security foundation. This seed key enables later derivation of full key pairs without requiring factory presence for complete PKI setup, thus ensuring security while reducing manufacturing time
Solution Approach 2:
The PKI setup process is segmented into two phases: (1) embedding seed key during manufacturing, and (2) generating full key pairs and certificates after manufacturing. This segmentation allows security to be established upfront while detailed credential generation occurs later, resolving the time-security tradeoff
2Reliability
If PKI key pairs and certificates are generated during factory manufacturing, then device trust verification is ensured, but manufacturing costs increase
Solution Approach 1:
Only the essential seed key is embedded during manufacturing, which is sufficient for later deriving complete PKI credentials. This preliminary action ensures trust verification capability while avoiding the high costs of complete on-factory PKI generation
Solution Approach 2:
The device uses its embedded seed key to self-generate its own key pairs and obtain certificates from remote authorities after manufacturing. This eliminates the need for expensive factory-based PKI generation infrastructure while maintaining trust verification
3Productivity
If key pair generation is performed after device manufacturing, then manufacturing time and costs are reduced, but network connection requirements may compromise security
Solution Approach 1:
The security-sensitive seed key embedding is separated from the less-sensitive key pair generation and certificate acquisition processes. The critical seed key is embedded during manufacturing without network connection, while subsequent operations that require network connectivity occur after manufacturing
Solution Approach 2:
The seed key is embedded as a preliminary security measure during manufacturing without requiring network connection. This preliminary action ensures that even if later operations require network access, the foundational security element was established in isolation
Data Source
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AI summary
A method of post-manufacture generation of the device certificate 20 for verifying an electronic device 2 according to a public key infrastructure is provided. The method comprises obtaining, at a certificate generating apparatus 40, a first key 42 associated with the device 2. A second key 22 for the electronic device is derived from the first key 42. The device certificate 20 for the PKI is generated with the second key acting as the public key 22 associated with the device certificate 20. In a corresponding way a private key 24 for the PKI can be generated by the electronic device 2 based on a shared first key 42. This approach enables the manufacturing cost for manufacturing an electronic device to be reduced whilst still enabling use of a PKI for attesting to properties of the device 2.