Trust Chain & Embedded Identity Architecture
How identity, attestation, and provisioning flow from silicon to cloud — and where the boundaries are.
From silicon to cloud, with no silent delegation
Each stage carries an explicit, verifiable assertion. No layer asks the next layer to "just trust me".
Silicon RoT
Immutable hardware base.
Secure Element / eUICC
Identity, key custody, attestation logic.
Firmware
Secure boot, signed updates, OS layer.
Operator network
Sandbox or production-ready connectivity.
Enterprise / cloud
Identity-aware services, audit, lifecycle.
A certificate hierarchy adapted to embedded constraints.
Embedded PKI is not "PKI on a smaller machine" — it is PKI under different assumptions. Devices do not always have a clock. Memory is constrained. Connectivity is intermittent. Revocation has to work without phoning home for every check. AmbiSecure designs hierarchies that respect those constraints while still producing assertions a back-end can trust.
- Per-device leaf identities issued under controlled conditions
- Intermediate hierarchy that maps to manufacturing and product lifecycle
- Revocation strategies that remain workable in low-connectivity deployments
- Key custody that never leaves the Secure Element
For the manufacturing-scale read of the same hierarchy — how a single secure element is personalised against the eSIM, V2X, and enterprise-PKI roots in one HSM-controlled step — see AmbiSecure on architectural unification across V2X, eSIM, IoT.
Verifiable claims about device state.
Attestation lets a relying party form an opinion about a device beyond "it knows a key". With attestation, a device can demonstrate that its firmware matches an expected version, that a specific applet is loaded inside its Secure Element, or that a credential has been provisioned under controlled conditions. We design attestation flows that produce statements an operator or enterprise back-end can actually act on.
- Attestation rooted in the Secure Element / eUICC
- Bindings between identity, firmware state, and applet inventory
- Verification logic that is implementable on the relying-party side
- Assumptions documented up front, not buried
- Device identity (leaf cert / public key)
- Firmware version digest
- Applet inventory hash
- Provisioning epoch
- Signature by SE-resident key
From manufacturing to decommissioning
Identity isn't a one-time event — it's a sequence of states that have to compose cleanly.
Manufacturing
Initial keys provisioned in controlled environment.
Initialization
Device-specific identity finalized.
In-service
Authentication, attestation, OTA updates.
Re-provision
Operator change, ownership transfer.
End-of-life
Identity retirement, key revocation.
Updates that don't break the trust chain
Field updates are the most common moment a trust model gets compromised. Architecture has to assume they will happen, frequently, under imperfect conditions.
Signed boot
Verifiable boot path that gates execution on signed code.
Signed updates
OTA payloads signed under a hierarchy whose root lives outside the device.
Rollback control
Anti-rollback mechanisms enforced inside the Secure Element.
Failure-safe
A failed update should not silently demote the device's trust status.
Re-attestation
Post-update attestation reconfirms device state to the back-end.
Audit trail
Update events are visible to lifecycle systems.
Want to walk this architecture in detail?
We can share design notes, threat model, and review the attestation flow with a security team.