OIDC vs SAML: Choosing the Right Identity Protocol
OIDC and SAML are both protocols for single sign-on (SSO), but they solve the problem differently. SAML uses XML-based assertions and suits enterprise web applications, while OIDC, built on OAuth 2.0, uses lightweight JSON web tokens and excels with mobile apps and modern APIs. Choose based on your application type, not protocol age.
Both OIDC and SAML are authentication protocols that let a user sign in once and access multiple applications without re-entering credentials. They delegate authentication to a central identity provider (IdP), so individual applications never handle passwords directly.
The difference lies in their design era and data format. SAML (Security Assertion Markup Language) arrived in the early 2000s, built for browser-based enterprise SSO. OIDC (OpenID Connect) is newer, layered on top of the OAuth 2.0 authorization framework, and designed for the web, mobile, and API world.
How it works
SAML defines an exchange between three parties: the user, the service provider (the app being accessed), and the identity provider that verifies identity.
When a user tries to access a protected application, the flow runs roughly like this:
- The service provider generates an authentication request and redirects the user to the IdP.
- The user authenticates with the identity provider (often via existing corporate credentials).
- The IdP returns a signed SAML assertion — an XML document asserting who the user is.
- The service provider validates the assertion's signature and grants access.
The SAML assertion carries identity attributes (name, email, group membership) inside XML. Because the assertion is digitally signed, the service provider can trust it without contacting the IdP again.
OIDC adds an identity layer on top of OAuth 2.0. Where OAuth 2.0 handles authorization (granting access to resources), OIDC adds authentication (verifying who the user is).
A typical OIDC login flow:
- The application (a "relying party," in OIDC terms) redirects the user to the IdP's authorization endpoint.
- The user authenticates.
- The IdP redirects back with an authorization code.
- The application exchanges that code at the token endpoint for an ID token — a JSON Web Token (JWT) containing identity claims.
The ID token is a signed JWT, compact and easy to parse in JavaScript or mobile code. Because OIDC uses JSON and standard REST-style calls rather than XML, it integrates cleanly with single-page apps, native mobile apps, and API gateways.
| Dimension | SAML | OIDC |
|---|---|---|
| Origins & Foundation | ||
| Released | 2005 (SAML 2.0) | 2014 |
| Built on | XML, SOAP heritage | OAuth 2.0, REST/JSON |
| Tokens & Transport | ||
| Token format | SAML assertion (XML) | ID token (JWT) |
| Transport | Browser redirects, form POST | Browser redirects, HTTP/JSON |
| Message size | Larger (verbose XML) | Smaller (compact JWT) |
| Use & Adoption | ||
| Primary use case | Enterprise web SSO | Mobile, SPA, API, modern web |
| Mobile support | Awkward | Native, first-class |
| Typical adopters | Legacy enterprise, government | Consumer apps, modern SaaS |
Both protocols are secure when implemented correctly, and both rely on digital signatures to prevent tampering. The risks are mostly in implementation, not the specs.
SAML’s main weak points are XML-specific: signature-wrapping attacks and XML parsing flaws have historically caught misconfigured service providers. Rigorous signature validation is essential.
OIDC inherits OAuth 2.0’s considerations: token leakage, redirect-URI manipulation, and the need to validate token signatures and audience claims. Using PKCE (Proof Key for Code Exchange) closes the most common gaps for public clients like mobile apps.
Neither protocol is inherently “more secure.” The deciding factor is the maturity of your implementation and your IdP.
Who Should Choose What
Yes. Many organizations run both. A common pattern: SAML handles legacy enterprise web apps while OIDC covers new mobile and API-driven services. Most modern identity providers support both protocols simultaneously, bridging old and new without forcing a single standard across every application.
This dual approach is often the realistic answer during migration — you adopt OIDC for new development without ripping out working SAML integrations.
FAQ
Choosing OIDC or SAML solves who the user is at the application’s front door. But once a user is authenticated, a separate question remains: what data can they actually reach, and under what conditions?
This is especially sharp for databases, where a single authenticated session can expose sensitive tables, columns, and records. Strong SSO at login doesn’t automatically translate into least-privilege access at the data layer.
This is where database access governance complements your identity protocol. DBHawk applies Zero Trust principles to database access, integrating with SSO, LDAP, and SAML while adding role-based and column-level access control, dynamic data masking, just-in-time access, and full activity auditing — so the identity you’ve verified at login maps to precisely the right level of data access.