ASAmbiSecureHardware-rooted security
Hardware-rooted identity on the BOM.
A secure element on the device, attestation in the issuance flow, EST-based rotation over the device’s normal connectivity, fleet-scale audit. The architecture that survives 10-year fielded products.
Why hardware-rooted device identity
A static device certificate with the key in flash is a weakness. One physical device’s key, extracted, becomes the entire SKU’s identity. A secure element on the BOM, with a key generated on-chip that never leaves, makes per-device identity provably unique.
The four layers
| Layer | Role |
|---|---|
| Silicon | Secure element on the device’s board. Common Criteria EAL5+ typical. Per-unit serial + factory attestation key. |
| Personalisation | At the SMT line. Keypair generated on-chip; CSR + attestation sent to issuing CA; certificate written back. Target under 2 seconds per board. |
| PKI | Issuing CA backed by HSM. Verifies attestation before signing. Audit logs every issuance. |
| Runtime | Device authenticates over mTLS using the certificate + attestation. Backend verifies both. EST re-enrolment for rotation. |
Constraints to design for
- SMT-line time budget. Personalisation has to fit the existing line cadence. Two seconds is the target.
- Field rotation. Devices in remote environments for years. Rotation has to happen over constrained connectivity without ever exposing the private key.
- 10-year horizon. Algorithms picked today have to be defensible in 2036. Cryptographic agility built in.
- BOM cost. Secure element on the bill of materials; cost fits the product margin.
Threat coverage
- Device cloning — per-device hardware-unique key + attestation.
- Key extraction — key never exists outside the secure element.
- Long-tail algorithm risk — EST re-enrolment supports rotation without retrieving devices.
- Supply-chain insider risk — CA signs only attestation-verified keys; rogue CA operator cannot issue against fake devices.
Operational realities
- Plan personalisation-rig redundancy at the line; rig is a single point of failure during production.
- Issuing CA must be reachable from the line; outage stops production.
- Initial certificate validity 3-5 years; EST rotation thereafter.
- Manufacturer attestation root is part of your supply-chain trust story; source secure elements from chip vendors with auditable provenance.
Related on the AmbiSecure site
Putting hardware identity onto a new product line?
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