Modern API security largely revolves around OAuth access tokens: authenticate a client or user, issue a token, and let APIs trust that token until it expires. But what happens when the security context changes while the token is still valid?

An account may be disabled, a device compromised, credentials stolen, or a session classified as high risk. In a zero trust architecture, APIs should be able to react to these changes immediately rather than waiting for tokens to expire.

This session explores how the OpenID Shared Signals Framework (SSF) and Continuous Access Evaluation Profile (CAEP) can provide an event-driven security layer for APIs. We will look at how identity providers, security systems, API gateways, and resource servers can exchange security signals and continuously re-evaluate access.

Using OAuth, Keycloak, and practical API scenarios, we’ll explore how shared signals can bridge the gap between traditional token-based API authorization and continuous zero trust enforcement.