LogiCore is configuring a federated identity setup where a web application accepts assertions from an external identity provider. What fundamental element must that relationship rely on?

TLS (Transport Layer Security) encrypts communication channels, ensuring confidentiality and integrity, but it is a communication protocol, not the fundamental basis of identity trust between providers.

In a federated identity setup, the service provider (web application) must explicitly trust the identity provider to vouch for a user's identity through assertions. This established trust relationship, often built using shared keys or certificates, is critical for the service provider to accept the authentication decisions made by the external identity provider.

Cloud Identity is a service offering identity management in the cloud, but the principle of trust between any identity provider and service provider (cloud or on-prem) is the fundamental element, not specifically 'Cloud Identity' itself.

Public key certificates are often used to establish and verify the trust relationship, for example, to sign assertions, but they are a mechanism to implement trust, not the abstract fundamental element of trust itself.