[[servlet-authentication-daoauthenticationprovider]]
= DaoAuthenticationProvider
:figures: servlet/authentication/unpwd

javadoc:org.springframework.security.authentication.dao.DaoAuthenticationProvider[] is an xref:servlet/authentication/architecture.adoc#servlet-authentication-authenticationprovider[`AuthenticationProvider`] implementation that uses a xref:servlet/authentication/passwords/user-details-service.adoc#servlet-authentication-userdetailsservice[`UserDetailsService`] and xref:servlet/authentication/passwords/password-encoder.adoc#servlet-authentication-password-storage[`PasswordEncoder`] to authenticate a username and password.

This section examines how `DaoAuthenticationProvider` works within Spring Security.
The following figure explains the workings of the xref:servlet/authentication/architecture.adoc#servlet-authentication-authenticationmanager[`AuthenticationManager`] in figures from the xref:servlet/authentication/passwords/index.adoc#servlet-authentication-unpwd-input[Reading the Username & Password] section.

.`DaoAuthenticationProvider` Usage
image::{figures}/daoauthenticationprovider.png[]

image:{icondir}/number_1.png[] The authentication `Filter` from the xref:servlet/authentication/passwords/index.adoc#servlet-authentication-unpwd-input[Reading the Username & Password] section passes a `UsernamePasswordAuthenticationToken` to the `AuthenticationManager`, which is implemented by xref:servlet/authentication/architecture.adoc#servlet-authentication-providermanager[`ProviderManager`].

image:{icondir}/number_2.png[] The `ProviderManager` is configured to use an xref:servlet/authentication/architecture.adoc#servlet-authentication-authenticationprovider[AuthenticationProvider] of type `DaoAuthenticationProvider`.

image:{icondir}/number_3.png[] `DaoAuthenticationProvider` looks up the `UserDetails` from the `UserDetailsService`.

image:{icondir}/number_4.png[] `DaoAuthenticationProvider` uses the xref:servlet/authentication/passwords/password-encoder.adoc#servlet-authentication-password-storage[`PasswordEncoder`] to validate the password on the `UserDetails` returned in the previous step.

image:{icondir}/number_5.png[] When authentication is successful, the xref:servlet/authentication/architecture.adoc#servlet-authentication-authentication[`Authentication`] that is returned is of type `UsernamePasswordAuthenticationToken` and has a principal that is the `UserDetails` returned by the configured `UserDetailsService`.
Ultimately, the returned `UsernamePasswordAuthenticationToken` is set on the xref:servlet/authentication/architecture.adoc#servlet-authentication-securitycontextholder[`SecurityContextHolder`] by the authentication `Filter`.
