lauthentification

Authentication, or l'authentification in French, is the process of proving that a person or entity is who they claim to be. It is a prerequisite for access to systems and data and is distinct from authorization, which governs permissions, and from accounting, which records activity.

Authentication relies on factors that can be classified as something you know (knowledge), something you have (possession), or something you are (inherence). Most systems use more than one factor; multi-factor authentication (MFA) combines two or more categories to reduce risk. Common examples include passwords, security tokens or smartphones generating codes, and biometrics such as fingerprints or facial recognition.

Methods include traditional passwords, one-time codes, hardware tokens, and biometric checks. Modern trends favor passwordless approaches that rely on public-key cryptography and device-bound credentials, such as WebAuthn/FIDO2, which can provide strong authentication without a shared secret.

Standards and protocols support authentication across web, API, and enterprise environments. Notable examples are OAuth 2.0 and OpenID Connect for delegated authentication and user sign-in, SAML for enterprise single sign-on, and WebAuthn with FIDO2 for passwordless authentication. Public key infrastructure (PKI) and digital certificates also play important roles in device or server authentication.

Security considerations include threats such as phishing, credential stuffing, and device compromise. Effective defense typically involves MFA, phishing-resistant methods where possible, strong credential hygiene, secure device management, and careful handling of biometric data to protect privacy and comply with regulations.