 Authentication

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]

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.