Hardware Security: Advanced Topics and Trends
What is the most appropriate benefit of efforts such as OpenTitan and Caliptra that publish the designs of root-of-trust circuits?
- AMany experts can examine and verify the design, making it easier to confirm security without relying on keeping the mechanism secret
- BBecause the design is published, each chip's secret keys may also be published along with it, so key management is no longer needed
- CPublishing the design removes the need to manage the processes of manufacturing chips and writing keys into them at the factory
Show answer and explanation
Answer: A. Many experts can examine and verify the design, making it easier to confirm security without relying on keeping the mechanism secret
The root of trust is the starting point of all trust in a device, so it is important to be able to confirm that its design has no errors or hidden functions. OpenTitan, as an open-source silicon root of trust, and Caliptra, as a root of trust to be built into data-center SoCs, had their designs published from 2019 onward with several companies participating (OpenTitan was announced in 2019 and Caliptra in 2022). This follows the principle that security should rest on keeping keys secret rather than on hiding the mechanism (Kerckhoffs's principle), and the results of design verification and testing can be shared. However, managing per-chip keys, controlling the manufacturing and key-provisioning processes, and confirming that the chips actually made match the published design are still needed separately.
- A. Correct. Many eyes can verify it, and the design does not rely on concealment.
- B. What is published is the design; each chip's keys stay secret.
- C. The manufacturing and key-provisioning processes must still be controlled even if the design is published.
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