OpenID Connect (OIDC) is an open standard for authentication that is built on top of the OAuth 2.0 framework. It enables clients (e.g., web or mobile applications) to verify the identity of a user based on the authentication performed by an Identity Provider (IdP). OIDC is commonly used for Single Sign-On (SSO), allowing users to authenticate once and access multiple applications or services securely.

Key Components of OIDC

1. ID Token: A JSON Web Token (JWT) that contains user identity information, such as the user's name, email, and other profile details. It is issued by the Identity Provider (IdP) after successful authentication.
2. Access Token: Used to grant authorization for accessing protected resources (such as APIs) on behalf of the user.
3. Authorization Code: A temporary code used in the Authorization Code Flow to obtain an access token and ID token.
4. UserInfo Endpoint: An endpoint provided by the IdP that returns additional user information (such as profile details) in a structured format.

How OIDC Works

1. A user attempts to access a resource on a client application (e.g., website or mobile app).
2. The client application redirects the user to the Identity Provider (IdP) for authentication.
3. The IdP authenticates the user (e.g., via password or multi-factor authentication).
4. Once authenticated, the IdP generates an ID Token and an Access Token and sends them back to the client application.
5. The client can use the Access Token to access protected resources or APIs on behalf of the user.
6. The client can also request additional user information through the UserInfo Endpoint.

Benefits of OIDC

• Simple Integration: OIDC is easy to implement, especially in web and mobile applications, due to its use of standard protocols (like OAuth 2.0 and JWT).
• Single Sign-On (SSO): Enables users to authenticate once and access multiple applications or services, reducing the need for multiple logins.
• Security: OIDC uses modern security features, such as JWT for token handling, ensuring secure and efficient communication.
• Interoperability: OIDC is widely adopted and supported by many Identity Providers and client applications, making it highly interoperable across platforms.

OpenID Connect (OIDC) is a modern and secure authentication protocol that builds on OAuth 2.0, offering a simple yet powerful way to implement Single Sign-On (SSO) across applications. With its reliance on standards like JWT and OAuth 2.0, OIDC enhances security, improves user experience, and simplifies identity management across multiple services.