OAuth 2.0, or Open Authorization version 2.0, is an authorization framework that allows third-party applications to gain limited access to a user's data without sharing their credentials.
User authentication is crucial in defining the security architecture of a Software-as-a-Service (SaaS) implementation. With the digital world's growing complexities and evolving threats, choosing the right authentication protocol can have significant implications. Among the myriad options available, two methodologies stand out – Single Sign-On (SSO) and OAuth 2.0. Here, we focus on OAuth 2.0 and discuss why it makes a compelling case for user authentication over traditional SSO systems.
Understanding OAuth 2.0
OAuth 2.0 is an open standard for access delegation, widely used for Internet users to grant websites or applications access to their information on other websites without giving them passwords. It separates the role of a user from that of a client, allowing the client to act on behalf of the user without sharing their credentials.
OAuth 2.0 operates through a series of handshakes involving various tokens. The basic steps include:
1. The client (an application requiring access) requests authorization from the resource owner (typically, the user).
2. If the user consents, the client receives an authorization grant, which it exchanges for an access token at the authorization server.
3. The client then uses the access token to access the protected resources from the resource server.
Advantages of OAuth 2.0 Over SSO
While SSO offers an easier login process, reducing password fatigue, and potentially lowering support costs related to password recovery, OAuth 2.0 brings in several distinct advantages:
1. Scoped Access: OAuth 2.0 permits scoped access, which means applications don't get full access to a user's account. They only receive limited, often read-only, access to the user's data. This is a significant advantage in terms of privacy and security.
2. No Shared Credentials: OAuth 2.0 doesn't require sharing the user's credentials with the client, which is a key security enhancement. The risk of a user's password being compromised is substantially reduced.
3. Delegation: OAuth 2.0 supports delegation, where a resource owner can delegate access to a client, which can act on behalf of the owner without impersonation. This is crucial for modern API-driven applications.
4. Revocable Access: OAuth 2.0 access tokens can be revoked by users at any time, providing better control over which applications have ongoing access to their data.
5. Standardization: OAuth 2.0 is a standardized protocol adopted widely across industries, including major players like Google, Facebook, and Microsoft. This standardization makes integration smoother and helps in staying up-to-date with security best practices.
Choosing OAuth 2.0 as your primary authentication method means embracing a secure, flexible, and modern approach to managing user access. Its capability of providing scoped and revocable access, coupled with delegation, and without sharing credentials, makes it a robust choice for any organization prioritizing security. While SSO still has its place, OAuth 2.0 represents a significant step forward in secure user authentication for government SaaS users.
CISA Guidelines
"Open ID Connect, OAuth 2.0, Kerberos, and SAML 2.0 are examples of protocols that use secure, non-password-based connections for SSO. Many social media-based SSO services that consumers use are based on Open ID Connect, allowing even consumers to use SSO while focusing on strong authentication for their primary login provider."
Read CISA's guide on Implementing Strong Authentication Here.