Ambimat GroupAmbimatAmbiSecureSIMAuthAmbiAutomationEngineering BlogAhmedabad · India · Est. 1982
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Smart cities.

When a single resident credential travels across transit, parking, library, recreation, parking-meters, and city services, the security architecture under it has to scale across a portfolio of issuers without leaking keys to anyone.

A city-wide credential, in practice

The DESFire application model fits this perfectly. One card, many applications, each with its own key set. Transit fares live in one application; library access in another; community-centre membership in a third. None of them share keys. A breach in one application does not propagate to the others.

The SAM model fits too. Different city departments can hold different SAM personalisation profiles — each owns their keys, none of them sees anyone else’s. The card is one credential the resident carries; the back office is several departments that never trust each other with their key material.

Smart-city deployments also touch the buildings inside them. The municipal HVAC, lighting, and BMS layer of a city hospital or civic centre is handled by our sibling team — the building-automation platform at AmbiAutomation — retrofitting existing VRV / VRF systems with a BACnet/MODBUS server and operator app. When the same resident card needs to badge into the building and the back-office HVAC needs hardware-rooted device identity, the two sides of the Ambimat ecosystem talk to each other.

Designing a city-wide credential program?

The hard part isn’t the cards or the readers — it’s the inter-departmental key-custody model. Talk to engineers.

Talk to engineers