For the latest stable version, please use Spring Security 6.3.1! |
OAuth 2.0 Resource Server
Spring Security supports protecting endpoints by using two forms of OAuth 2.0 Bearer Tokens:
-
Opaque Tokens
This is handy in circumstances where an application has delegated its authority management to an authorization server (for example, Okta or Ping Identity). This authorization server can be consulted by resource servers to authorize requests.
This section details how Spring Security provides support for OAuth 2.0 Bearer Tokens.
Working samples for both JWTs and Opaque Tokens are available in the Spring Security Samples repository. |
Now we can consider how Bearer Token Authentication works within Spring Security. First, we see that, as with Basic Authentication, the WWW-Authenticate header is sent back to an unauthenticated client:
![bearerauthenticationentrypoint](../../../_images/servlet/oauth2/bearerauthenticationentrypoint.png)
The figure above builds off our SecurityFilterChain
diagram.
First, a user makes an unauthenticated request to the
/private
resource for which the user is not authorized.
Spring Security’s
FilterSecurityInterceptor
indicates that the unauthenticated request is Denied by throwing an AccessDeniedException
.
Since the user is not authenticated,
ExceptionTranslationFilter
initiates Start Authentication.
The configured AuthenticationEntryPoint
is an instance of BearerTokenAuthenticationEntryPoint
, which sends a WWW-Authenticate
header.
The RequestCache
is typically a NullRequestCache
that does not save the request, since the client is capable of replaying the requests it originally requested.
When a client receives the WWW-Authenticate: Bearer
header, it knows it should retry with a bearer token.
The following image shows the flow for the bearer token being processed:
![bearertokenauthenticationfilter](../../../_images/servlet/oauth2/bearertokenauthenticationfilter.png)
The figure builds off our SecurityFilterChain
diagram.
When the user submits their bearer token, the
BearerTokenAuthenticationFilter
creates a BearerTokenAuthenticationToken
which is a type of Authentication
by extracting the token from the HttpServletRequest
.
Next, the
HttpServletRequest
is passed to the AuthenticationManagerResolver
, which selects the AuthenticationManager
. The BearerTokenAuthenticationToken
is passed into the AuthenticationManager
to be authenticated.
The details of what AuthenticationManager
looks like depends on whether you’re configured for JWT or opaque token.
If authentication fails, then Failure
-
The SecurityContextHolder is cleared out.
-
The
AuthenticationEntryPoint
is invoked to trigger the WWW-Authenticate header to be sent again.
If authentication is successful, then Success.
-
The Authentication is set on the SecurityContextHolder.
-
The
BearerTokenAuthenticationFilter
invokesFilterChain.doFilter(request,response)
to continue with the rest of the application logic.