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Producing <saml2:AuthnRequest>
s
As stated earlier, Spring Security’s SAML 2.0 support produces a <saml2:AuthnRequest>
to commence authentication with the asserting party.
Spring Security achieves this in part by registering the Saml2WebSsoAuthenticationRequestFilter
in the filter chain.
This filter by default responds to endpoint /saml2/authenticate/{registrationId}
.
For example, if you were deployed to rp.example.com
and you gave your registration an ID of okta
, you could navigate to:
and the result would be a redirect that included a SAMLRequest
parameter containing the signed, deflated, and encoded <saml2:AuthnRequest>
.
Changing How the <saml2:AuthnRequest>
Gets Stored
Saml2WebSsoAuthenticationRequestFilter
uses an Saml2AuthenticationRequestRepository
to persist an AbstractSaml2AuthenticationRequest
instance before sending the <saml2:AuthnRequest>
to the asserting party.
Additionally, Saml2WebSsoAuthenticationFilter
and Saml2AuthenticationTokenConverter
use an Saml2AuthenticationRequestRepository
to load any AbstractSaml2AuthenticationRequest
as part of authenticating the <saml2:Response>
.
By default, Spring Security uses an HttpSessionSaml2AuthenticationRequestRepository
, which stores the AbstractSaml2AuthenticationRequest
in the HttpSession
.
If you have a custom implementation of Saml2AuthenticationRequestRepository
, you may configure it by exposing it as a @Bean
as shown in the following example:
-
Java
-
Kotlin
@Bean
Saml2AuthenticationRequestRepository<AbstractSaml2AuthenticationRequest> authenticationRequestRepository() {
return new CustomSaml2AuthenticationRequestRepository();
}
@Bean
open fun authenticationRequestRepository(): Saml2AuthenticationRequestRepository<AbstractSaml2AuthenticationRequest> {
return CustomSaml2AuthenticationRequestRepository()
}
Changing How the <saml2:AuthnRequest>
Gets Sent
By default, Spring Security signs each <saml2:AuthnRequest>
and send it as a GET to the asserting party.
Many asserting parties don’t require a signed <saml2:AuthnRequest>
.
This can be configured automatically via RelyingPartyRegistrations
, or you can supply it manually, like so:
-
Boot
-
Java
-
Kotlin
spring:
security:
saml2:
relyingparty:
okta:
identityprovider:
entity-id: ...
singlesignon.sign-request: false
RelyingPartyRegistration relyingPartyRegistration = RelyingPartyRegistration.withRegistrationId("okta")
// ...
.assertingPartyDetails(party -> party
// ...
.wantAuthnRequestsSigned(false)
)
.build();
var relyingPartyRegistration: RelyingPartyRegistration =
RelyingPartyRegistration.withRegistrationId("okta")
// ...
.assertingPartyDetails { party: AssertingPartyDetails.Builder -> party
// ...
.wantAuthnRequestsSigned(false)
}
.build()
Otherwise, you will need to specify a private key to RelyingPartyRegistration#signingX509Credentials
so that Spring Security can sign the <saml2:AuthnRequest>
before sending.
By default, Spring Security will sign the <saml2:AuthnRequest>
using rsa-sha256
, though some asserting parties will require a different algorithm, as indicated in their metadata.
You can configure the algorithm based on the asserting party’s metadata using RelyingPartyRegistrations
.
Or, you can provide it manually:
-
Java
-
Kotlin
String metadataLocation = "classpath:asserting-party-metadata.xml";
RelyingPartyRegistration relyingPartyRegistration = RelyingPartyRegistrations.fromMetadataLocation(metadataLocation)
// ...
.assertingPartyDetails((party) -> party
// ...
.signingAlgorithms((sign) -> sign.add(SignatureConstants.ALGO_ID_SIGNATURE_RSA_SHA512))
)
.build();
var metadataLocation = "classpath:asserting-party-metadata.xml"
var relyingPartyRegistration: RelyingPartyRegistration =
RelyingPartyRegistrations.fromMetadataLocation(metadataLocation)
// ...
.assertingPartyDetails { party: AssertingPartyDetails.Builder -> party
// ...
.signingAlgorithms { sign: MutableList<String?> ->
sign.add(
SignatureConstants.ALGO_ID_SIGNATURE_RSA_SHA512
)
}
}
.build()
The snippet above uses the OpenSAML SignatureConstants class to supply the algorithm name.
But, that’s just for convenience.
Since the datatype is String , you can supply the name of the algorithm directly.
|
Some asserting parties require that the <saml2:AuthnRequest>
be POSTed.
This can be configured automatically via RelyingPartyRegistrations
, or you can supply it manually, like so:
-
Java
-
Kotlin
RelyingPartyRegistration relyingPartyRegistration = RelyingPartyRegistration.withRegistrationId("okta")
// ...
.assertingPartyDetails(party -> party
// ...
.singleSignOnServiceBinding(Saml2MessageBinding.POST)
)
.build();
var relyingPartyRegistration: RelyingPartyRegistration? =
RelyingPartyRegistration.withRegistrationId("okta")
// ...
.assertingPartyDetails { party: AssertingPartyDetails.Builder -> party
// ...
.singleSignOnServiceBinding(Saml2MessageBinding.POST)
}
.build()
Customizing OpenSAML’s AuthnRequest
Instance
There are a number of reasons that you may want to adjust an AuthnRequest
.
For example, you may want ForceAuthN
to be set to true
, which Spring Security sets to false
by default.
You can customize elements of OpenSAML’s AuthnRequest
by publishing an OpenSaml4AuthenticationRequestResolver
as a @Bean
, like so:
-
Java
-
Kotlin
@Bean
Saml2AuthenticationRequestResolver authenticationRequestResolver(RelyingPartyRegistrationRepository registrations) {
RelyingPartyRegistrationResolver registrationResolver =
new DefaultRelyingPartyRegistrationResolver(registrations);
OpenSaml4AuthenticationRequestResolver authenticationRequestResolver =
new OpenSaml4AuthenticationRequestResolver(registrationResolver);
authenticationRequestResolver.setAuthnRequestCustomizer((context) -> context
.getAuthnRequest().setForceAuthn(true));
return authenticationRequestResolver;
}
@Bean
fun authenticationRequestResolver(registrations : RelyingPartyRegistrationRepository) : Saml2AuthenticationRequestResolver {
val registrationResolver : RelyingPartyRegistrationResolver =
new DefaultRelyingPartyRegistrationResolver(registrations)
val authenticationRequestResolver : OpenSaml4AuthenticationRequestResolver =
new OpenSaml4AuthenticationRequestResolver(registrationResolver)
authenticationRequestResolver.setAuthnRequestCustomizer((context) -> context
.getAuthnRequest().setForceAuthn(true))
return authenticationRequestResolver
}