Authentication verifies a claimed identity or the origin of information using evidence accepted by a system. A password demonstrates knowledge of a secret; a signed challenge can demonstrate possession of a private key. It differs from authorization: establishing which user is present does not determine which files that user may read. The relying party must also check freshness and context so an old valid message cannot simply be replayed in a different interaction. A cryptographic assertion is useful only when its issuer, recipient and validation rules are understood.[ref]
An authentication goal in which both participants establish the identity and relevant participation of the other. Freshness, agreement on parameters and completed participation are separate properties that a protocol should specify.
An identity provider authenticates a subject and issues an identity assertion for another service, the relying party. In federated login, the application trusts specified assertions from a configured provider rather than collecting the user's password itself. The application still validates the assertion's signature, intended audience, freshness and relevant protocol state, and performs its own authorization. A provider account and an application account need not be identical records. Trust in the provider and correct protocol validation are assumptions of the federation, not consequences of the login button's appearance.
Articles by others on the same topic
Authentication is the process of verifying the identity of a user, device, or system to ensure that they are who they claim to be. It is a critical component of security protocols in various fields, including computing, networking, and information security. The primary goal of authentication is to protect systems and data from unauthorized access and to ensure that sensitive information is only accessible to authorized users.