Skip to main content

OAuth2

What is OAuth2?

OAuth2 (Open Authorization version 2.0) is an authorization framework that enables a third-party application to obtain limited access to an HTTP service, either on behalf of a resource owner or by allowing the third-party application to obtain access on its own behalf. OAuth2 is widely used as a way for users to grant websites or applications access to their information on other websites without giving them their passwords.

OAuth2 works by using tokens that grant access to specific resources. When a user logs into an application using OAuth2, they are redirected to the authorization server, where they are prompted to grant the application access to their resources. Once the user grants access, the authorization server issues an access token to the application, which it can use to access the user's resources on the protected server.

OAuth2 provides a standardized way for different applications to communicate and share resources securely. It is widely used by major web companies such as Google, Facebook, and Twitter, as well as by many smaller developers and businesses.

What is the difference between OAuth and OAuth2?

OAuth and OAuth2 are two versions of the OAuth protocol, which is used for authentication and authorization between applications. While they share some similarities, there are several key differences between OAuth and OAuth2:

  • Authorization Grants: In OAuth, only one type of authorization grant (called "Authorization Code Grant") was available. In OAuth2, there are several different types of authorization grants available, including "Authorization Code Grant", "Implicit Grant", "Resource Owner Password Credentials Grant", and "Client Credentials Grant". These grants provide more flexibility in how access is granted.
  • Token Format: In OAuth, only one type of token format (called "OAuth Token") was used. In OAuth2, there are two types of tokens: access tokens and refresh tokens. Access tokens are used to access protected resources, while refresh tokens are used to obtain new access tokens.
  • Client Registration: In OAuth, clients were not required to register with the authorization server. In OAuth2, client registration is mandatory. This helps the authorization server maintain a list of trusted clients and improve security.
  • Security: OAuth2 is considered more secure than OAuth. It includes additional security features such as token expiration and token revocation.
  • Scope: OAuth2 includes the concept of "scope," which allows the user to specify which resources the client can access. This makes it more flexible than OAuth, which had limited control over access.

In summary, OAuth2 is a more flexible and secure protocol than OAuth, with additional features such as multiple authorization grants, token formats, client registration, and scope.

What is the difference between OAuth2 and SSO (Single-Sign-On)?

OAuth2 and SSO (Single-Sign-On) are related but different concepts. SSO is a mechanism that allows users to authenticate only once and access multiple systems and resources without having to log in again. It simplifies the authentication process and reduces the burden of remembering multiple credentials for different applications. OAuth2 is an authorization framework that enables third-party applications to access a user's data without compromising the user's login credentials. OAuth2 can be used as a part of an SSO solution, but it is not a complete SSO solution on its own.

OAuth2 does not provide a complete SSO solution because it only deals with authorization, not authentication. OAuth2 enables a user to authenticate once and grant permission for a third-party application to access their data on their behalf. However, it does not provide a mechanism for the user to authenticate again when accessing other resources. SSO, on the other hand, provides a complete authentication and authorization solution that enables a user to authenticate once and access multiple resources without having to log in again.

OAuth2 and SSO are often used together to provide a complete authentication and authorization solution. OAuth2 can be used to delegate user authorization to a third-party application, while SSO can be used to authenticate the user and provide a single point of entry for accessing multiple resources. In such a scenario, the user authenticates once through the SSO provider, and the SSO provider generates a token that can be used to authenticate the user to other resources. The OAuth2 access token can be used to authorize the third-party application to access the user's data on their behalf.

In summary, while OAuth2 and SSO are related, they serve different purposes. OAuth2 is an authorization framework that enables third-party applications to access a user's data without compromising the user's login credentials. SSO is a mechanism that allows users to authenticate only once and access multiple systems and resources without having to log in again. OAuth2 can be used as a part of an SSO solution, but it is not a complete SSO solution on its own.