Key Takeaways

Authentication verifies who a user is, while authorization determines what they can access or do. Protocols such as SSO, WebAuthn, OAuth2, and OpenID Connect strengthen digital identity verification, reduce friction, and enable secure interactions across systems. Clear distinctions between authentication and authorization help organizations improve security while delivering smoother user experiences.

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Why the Distinction Matters

Authentication and authorization are often confused, but they serve different purposes.

• Authentication verifies a user's or system's identity. It typically relies on credentials such as usernames and passwords, biometric data, or security tokens. By confirming identity, authentication ensures that only approved users gain access.
  
  
• Authorization determines what actions a verified user can perform and which resources they can access. It assigns permissions based on identity, role, or context.
  

In short, authentication is about who you are, and authorization is about what you can do.

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Authentication Methods

Single Sign-On (SSO)

Single sign-on allows users to access multiple websites, services, or applications with a single set of login credentials. A central authentication server manages these credentials, so users log in once and then access other applications automatically.

Benefits include:

• Easier user experience by reducing the need for multiple logins.
• Lower risk of password reuse or phishing attacks.
• Simplified compliance for organizations.

However, SSO also introduces a single point of failure. If those credentials are compromised, multiple systems are at risk.

Types of SSO include:

• Web-based SSO: Authentication through a browser for access to web apps.
• Federated SSO: Access across organizations or domains using standards like SAML or OpenID Connect.
• Enterprise SSO: Internal authentication integrated with directory services such as Active Directory or LDAP.

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Web Authentication (WebAuthn)

WebAuthn, developed by the W3C and FIDO Alliance, enables authentication with public key cryptography rather than passwords. Supported by major technology providers, WebAuthn advances passwordless authentication and reduces reliance on weak credentials.

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Authorization Methods

OAuth and OAuth2

OAuth is a widely adopted authorization framework that lets users grant third-party applications access to resources without sharing their credentials. Instead, OAuth uses access tokens, which can be revoked at any time. It is widely used by major technology companies, including Facebook, Google, and Twitter, and is an important component of modern web and mobile application development.

OAuth 2 is a newer version of OAuth that simplifies the authorization process and provides better support for mobile and cloud-based applications. It introduces new concepts, such as access tokens and scopes, to make it easier to implement and use. OAuth 2 also supports various types of authorization flows, including implicit, authorization code, client credentials, and resource owner password credentials. These flows allow for more flexibility in the authorization process, making it easier for developers to integrate OAuth into their applications.

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OpenID Connect

OpenID Connect is an interoperable authentication protocol based on the OAuth 2.0 family of specifications. This comes to form a simple identity layer on top of the OAuth 2.0 protocol.

OpenID Connect lets websites and apps authenticate their users across other websites and apps without having to own and manage password files. For the app builder or website owner, it provides a secure, verifiable answer to the question: “What is the identity of the person currently using the browser or native app that is connected to me?” In other words, it lets app and website owners authenticate users without taking on the responsibility of storing and managing passwords and the associated security and legal risk of custodying personal data.

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OpenID for Verifiable Credentials (OpenID4VC)

OpenID4VC extends these principles to verifiable credentials. It allows issuers, holders, and verifiers to interact directly, enabling privacy-preserving credential presentation without dependence on intermediaries.

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Authentication vs Authorization in Practice

In real-world systems, authentication and authorization often work together:

• SSO provides authentication so users can log in once to access multiple services.
• OAuth2 provides authorization so those services can share data without exposing login credentials.

For example, a user could authenticate through an SSO portal, then authorize a healthcare app to pull data from their insurer. Combined, these protocols make digital interactions secure, efficient, and user-friendly.

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Why This Matters

Authentication and authorization are foundational to secure, seamless digital experiences. Authentication confirms who a user is, and authorization determines what they can access. When combined through standards like SSO, WebAuthn, OAuth2, and OpenID Connect, they enable trusted, privacy-preserving interactions at scale. These protocols aren’t just technical choices, they’re essential for building secure, user-centric digital identity systems.