End-to-end trust chain

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.

Embedded PKI

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
PKI HIERARCHY (illustrative)
Root of trust
Manufacturing intermediate
Product / SKU intermediate
Per-device leaf identity
Attestation

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
ATTESTATION CONTENTS (typical)
  • Device identity (leaf cert / public key)
  • Firmware version digest
  • Applet inventory hash
  • Provisioning epoch
  • Signature by SE-resident key
Provisioning lifecycle

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.

Secure OTA

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.

SB

Signed boot

Verifiable boot path that gates execution on signed code.

UP

Signed updates

OTA payloads signed under a hierarchy whose root lives outside the device.

RB

Rollback control

Anti-rollback mechanisms enforced inside the Secure Element.

FB

Failure-safe

A failed update should not silently demote the device's trust status.

AT

Re-attestation

Post-update attestation reconfirms device state to the back-end.

AU

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.

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