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Basic Authentication
This section provides details on how Spring Security provides support for Basic HTTP Authentication for servlet-based applications.
This section describes how HTTP Basic Authentication works within Spring Security. First, we see the WWW-Authenticate header is sent back to an unauthenticated client:
![basicauthenticationentrypoint](../../../_images/servlet/authentication/unpwd/basicauthenticationentrypoint.png)
The preceding figure builds off our SecurityFilterChain
diagram.
First, a user makes an unauthenticated request to the resource
/private
for which it is not authorized.
Spring Security’s
AuthorizationFilter
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 BasicAuthenticationEntryPoint
, 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
header, it knows it should retry with a username and password.
The following image shows the flow for the username and password being processed:
![basicauthenticationfilter](../../../_images/servlet/authentication/unpwd/basicauthenticationfilter.png)
The preceding figure builds off our SecurityFilterChain
diagram.
When the user submits their username and password, the
BasicAuthenticationFilter
creates a UsernamePasswordAuthenticationToken
, which is a type of Authentication
by extracting the username and password from the HttpServletRequest
.
Next, the
UsernamePasswordAuthenticationToken
is passed into the AuthenticationManager
to be authenticated.
The details of what AuthenticationManager
looks like depend on how the user information is stored.
If authentication fails, then Failure.
-
The SecurityContextHolder is cleared out.
-
RememberMeServices.loginFail
is invoked. If remember me is not configured, this is a no-op. See theRememberMeServices
interface in the Javadoc. -
AuthenticationEntryPoint
is invoked to trigger the WWW-Authenticate to be sent again. See theAuthenticationEntryPoint
interface in the Javadoc.
If authentication is successful, then Success.
-
The Authentication is set on the SecurityContextHolder.
-
RememberMeServices.loginSuccess
is invoked. If remember me is not configured, this is a no-op. See theRememberMeServices
interface in the Javadoc. -
The
BasicAuthenticationFilter
invokesFilterChain.doFilter(request,response)
to continue with the rest of the application logic. See theBasicAuthenticationFilter
Class in the Javadoc
By default, Spring Security’s HTTP Basic Authentication support is enabled. However, as soon as any servlet based configuration is provided, HTTP Basic must be explicitly provided.
The following example shows a minimal, explicit configuration:
-
Java
-
XML
-
Kotlin
@Bean
public SecurityFilterChain filterChain(HttpSecurity http) {
http
// ...
.httpBasic(withDefaults());
return http.build();
}
<http>
<!-- ... -->
<http-basic />
</http>
@Bean
open fun filterChain(http: HttpSecurity): SecurityFilterChain {
http {
// ...
httpBasic { }
}
return http.build()
}