ShibbolethSSOConfiguration

Options common to most/all profiles:

Guidance

Modifying the security configuration is usually done to:

• specify an alternate signing or decryption key to use

• control signing or encryption algorithms (but for metadata you control, it's advisable to control algorithms by using an extension to specify supported algorithms).

The two interceptor lists allow the much less commonly used profile interceptor injection points to be used. This is largely a Java-based way of doing very low-level sorts of “message rewriting” hackery that might otherwise be impossible to pull off. One use case for the inbound side might be picking up non-standard parameters in a SAML request.

Options common to profiles that perform authentication:

Guidance

The postAuthenticationFlows property is used to apply special processing to requests, such as attribute release consent, password expiration warnings, authorization checks, or other custom processing.

Examples of postAuthenticationFlows property

<bean id="shibboleth.DefaultRelyingParty" parent="RelyingParty">

	<!-- Add consent to Shibboleth SSO profile. -->
	<bean parent="Shibboleth.SSO" p:postAuthenticationFlows="attribute-release" />

	<!-- Add consent, followed by expiring password check, to SAML 2 SSO profile. -->
	<bean parent="SAML2.SSO" p:postAuthenticationFlows="#{{'attribute-release', 'expiring-password'}}" />

	<!-- Return interceptors from a function bean (not shown). -->
	<bean parent="Shibboleth.SSO" p:postAuthenticationFlowsLookupStrategy-ref="InterceptorsFunction" />

</bean>

With the increased use of multi-factor authentication, it is more common to find RPs that can specify authentication requirements, but there are still many cases, particular with commercial services, in which it becomes necessary to force the use of specific login methods. This can be achieved using the defaultAuthenticationMethods property by specifying one or more corresponding Principals to trigger the use of stronger methods.

Note that you must also prevent a malicious actor from overriding this preference for a SAML 2.0 SP by manufacturing a request, via one of two means:

• For a SAML 2.0 SP that can sign its requests, its metadata can be modified with the AuthnRequestsSigned flag to indicate that its requests must be signed.

• Alternatively, the disallowedFeatures property may be set with the SAML2.SSO.FEATURE_AUTHNCONTEXT bean to block use of the SAML 2.0 <RequestedAuthnContext> feature.

At present, no other authentication profiles support a feature capable of requesting the authentication method.

Examples of defaultAuthenticationMethods property

<!-- NOTE: these example.org constants are examples and are not suitable for real use. -->
<bean id="MFASAML2Principal" parent="shibboleth.SAML2AuthnContextClassRef"
	c:_0="http://example.org/ac/classes/mfa" />
<bean id="MFASAML1Principal" parent="shibboleth.SAML1AuthenticationMethod"
	c:_0="http://example.org/ac/classes/mfa" />

<bean id="shibboleth.DefaultRelyingParty" parent="RelyingParty">

	<!-- Require MFA with Shibboleth SSO profile. -->
	<bean parent="Shibboleth.SSO">
		<property name="defaultAuthenticationMethods">
			<list>
				<ref bean="MFASAML1Principal" />
			</list>
		</property>
	</bean>

	<!-- Require MFA with SAML 2 SSO profile. -->
	<bean parent="SAML2.SSO" p:disallowedFeatures-ref="SAML2.SSO.FEATURE_AUTHNCONTEXT">
		<property name="defaultAuthenticationMethods">
			<list>
				<ref bean="MFASAML2Principal" />
			</list>
		</property>
	</bean>

</bean>

Options common to SAML profiles:

Guidance

It isn't too common to need any of these options, and they should be changed only with care.

The signResponses default varies by profile, see the notes on the individual profile pages.

Options common to SAML profiles that may transmit messages via SAML Artifact (a pass by reference instead of value, followed by a callback).

Guidance

You shouldn't really need to modify this, as artifacts are rarely used anymore, and if they are, the default configuration suffices. The main reason you might change it is to switch a SAML 1.1 SSO configuration from Type 1 to Type 2 artifacts, but that's very obscure. If it ever comes up, we will provide an example.

With SAML 2.0, there is a valid case for customizing the configuration on a per-node basis by exposing dedicated resolution endpoints on each node, and making sure a node issues artifacts that will be resolved by that node. This is already exposed for you via the idp.artifact.endpointIndex property.

Profile-Specific

Options specific to the Shibboleth / SAML 1.1 SSO profile:

Guidance

The historical default for the Shibboleth profile of SAML 1.1 was to issue only authentication information through the normal channel and rely on a back-chanel to query for attributes, due to the lack of support for XML Encryption in SAML 1.1.

This a very commonly modified setting because of the gradual deprecation of the use of the back channel and support for attribute queries. With the very limited use of SAML 1.1, it's usually simpler to forgo supporting queries and simply push attributes for the few legacy systems left, relying on the TLS protections between the client and servers to protect the user's data from passive observation.

Note that the value of this setting is ignored when SAML artifacts are used, it's always true in those cases because the data is passed over a back-channel anyway.