Security · optional
PQ Shield.
Optional post-quantum (PQ) encryption between your phone and that house (further security beyond standard SSL/TLS).
Optional post-quantum (PQ) encryption between your phone and that house (further security beyond standard SSL/TLS).
PQ Shield is an optional layer of post-quantum (PQ) encryption between the Patrimony Collection app on your iPhone and that house’s Home Assistant. It adds further security beyond standard SSL/TLS on the live glance path. Keys stay on your phone and that house. It does not send live house state through Patrimony’s cloud.
On Connections, status reads Present, Off, or Unavailable.
Some recorded encrypted traffic might one day be decrypted if large-scale quantum computers arrive (the intuition often called “harvest now, decrypt later”).
PQ Shield is designed so the live payloads we wrap between phone and that house use key establishment meant to remain hard even in that future.
Standard SSL/TLS still protects the connection. PQ Shield is an extra layer for those payloads (further post-quantum (PQ) security beyond standard SSL/TLS), not a promise that nothing can ever be attacked.
iPhone (Patrimony Collection) This house (Home Assistant)
┌──────────────────────────┐ ┌──────────────────────────────┐
│ App │ │ Patrimony custom component │
│ Keychain (session keys) │ │ House storage (session keys) │
└────────────┬─────────────┘ └──────────────▲───────────────┘
│ │
│ TLS / HTTPS │
│ + optional PQ Shield │
│ app-layer session encryption │
└────────────────────────────────────────┘
Patrimony cloud (accounts, invites, property list, push)
- not in the live crypto path; does not hold PQ Shield keys
Available when your house’s Patrimony integration supports PQ Shield.
PQ Shield does not change the TLS/SSL handshake between your iPhone and that house. Ordinary HTTPS/TLS still carries the connection. When PQ Shield is Present, an additional app-layer session protects the live glance payloads on that same path: a hybrid post-quantum key establishment at Enable (and again at Rotate), then AES-256-GCM for those snapshots. Keys for that session stay on the phone and that house. Patrimony’s cloud is not on this live crypto path.
AES-256 is not the weak part of today’s story. A 256-bit key still takes on the order of 2256 guesses classically, and on the order of 2128 even under Grover’s algorithm, still far beyond anything practical. The harvest-now, decrypt-later concern sits mainly in key establishment that relies on elliptic-curve Diffie-Hellman alone (for example X25519): roughly ~128-bit classical security, and vulnerable to Shor’s algorithm on a large enough quantum computer, so traffic recorded today could be opened later if only that classical exchange protected the keys.
PQ Shield applies the same idea above TLS. It keeps strong 256-bit bulk encryption for the payloads it wraps (AES-256-GCM in our session), and closes that key-establishment hole for those payloads by using a hybrid encapsulation: X25519 together with ML-KEM-768 (NIST Category 3; commonly described as targeting roughly AES-192-class strength against quantum attack, with published estimates on the order of ~2182 classical / ~2166 quantum operations). An attacker must break both pieces, not only the curve. You are not “more encrypted than 256”; you are keeping 256-bit bulk crypto for the shielded payloads and hardening how that session key is established.
The cost of the upgrade is mostly size, and it shows at Enable / Rotate, not on every glance update. Classical X25519 uses a 32-byte public key. Our hybrid public key is 1216 bytes (1184-byte ML-KEM-768 public key concatenated with a 32-byte X25519 public key). The matching hybrid encapsulation ciphertext is 1120 bytes (1088 + 32). After the session is Present, live snapshots carry only a short nonce and AES-256-GCM ciphertext, not a fresh hybrid encapsulation on each update.
This section describes PQ Shield’s app-layer design. It does not claim that TLS itself is post-quantum, that the product is quantum-proof, or that a compromised Home Assistant or stolen house token is protected.
Connections surfaces (hostnames, addresses, and tokens omitted). Lab / demo house naming.
When PQ Shield is Present for that house, a PQ Shield badge appears on the house card (top-right with the local time and status).
“Lindy” nods to the Lindy effect: what has lasting use tends to keep lasting (a bias toward houses, systems, and habits that endure).
PQ Shield fits that posture: looking ahead to a longer-lived threat model for the private link between your phone and a house you mean to keep, without shouting absolute security.