---
type: entity
tags: [parking, hardware, security, crypto]
sources: [parking-system-architecture]
updated: 2026-06-14
---

# ATECC608 (secure element)

An inexpensive **secure element** holding a signing key that **cannot be extracted, even by
someone who owns the machine**. The keystone of integrity in this system. (See
[[parking-system-architecture]] §3, §7.)

Two distinct uses:

1. **Host-side event signing.** Each event in the [[append-only-event-chain]] is signed by the
   ATECC608 on the host machine. This is what makes the hash chain **unforgeable** rather than
   merely self-consistent.
2. **Custom controller command authentication.** On the [[esp32-custom-controller]], it holds
   the key(s) for [[challenge-response-auth]] — generated on-chip, non-extractable, so popping
   the cabinet and dumping flash yields nothing usable.

Confirming ATECC608 wiring/usage on both ends is [[open-questions]] #6. Listed in the [[bom]]
on the host machine.