Offline authentication and validator latency
All AmbiSecure engineering content tagged Offline Authentication, newest first. Newer entries reflect current thinking; earlier entries come from the engineering archive.
Offline authentication proves identity without a live connection to a central server — essential for transit gates, border control, and field access where latency or connectivity cannot be assumed. It relies on cryptographic verification against locally held trust anchors (public keys or certificates) rather than an online lookup.
This category covers the engineering of offline-capable credentials: how a reader validates a card or document using signatures and pre-distributed keys, how revocation is handled without constant connectivity, and where secure elements make offline trust possible. The emphasis is on designing for intermittent or absent connectivity without weakening assurance.
Articles tagged Offline Authentication
Frequently asked questions
How can authentication work offline?
The verifier holds trusted public keys or certificates and checks a signature the credential produces locally — for example ePassport Passive Authentication or a signed transit token — so no online lookup is required to establish authenticity.
How is revocation handled offline?
Through periodically distributed revocation lists or short-lived credentials: the system trades some freshness for availability, refreshing trust data when connectivity is available rather than per-transaction.
Why are secure elements important for offline use?
Offline verification cannot rely on a server to protect secrets, so the credential's key must be non-exportable and held in tamper-resistant hardware to resist cloning in the field.
What is the latency budget at a transit gate?
A few hundred milliseconds — short enough that a network round trip is not available. That constraint is what forces the trust decision onto the card and the validator.
What are the trade-offs of authenticating offline?
Speed and availability against freshness. An offline validator cannot know about a revocation issued seconds ago, so systems bound the exposure with short-lived credentials and regular revocation distribution.