SAML 2.0 provides a mechanism to request an authentication class reference. For more information, see the SAML 2.0 Core specification in section 3.3.2.2.1.
The Service Provider sends the following sample code in the <AuthnRequest>:
<samlp:RequestedAuthnContext> <saml:AuthnContextClassRef>urn:oasis:names:tc:SAML:2.0:ac:classes:MobileOneFactorContract</saml:AuthnContextClassRef> </samlp:RequestedAuthnContext>
SAML 2.0 defines a bunch of URNs that corresponds to authentication classes. For more information, see SAML 2.0 Authentication Context.
Some of the authentication class types of Advanced Authentication match the SAML 2.0 references. The Advanced Authentication auth class types are defined in an enum named AuthClassType.
In this XML example, the SAML class reference URN maps to the Advanced Authentication’s AuthClassType.MOBILE_ONE_FACTOR_CONTRACT. The Advanced Authentication value is mapped to NaafAuthMethod.SMARTPHONE (or NaafAuthMethod.SWISSCOM).The code in NaafEventContractExecutable.filterChains selects from the available chains any chain that contains one of its methods (in this example) SMARTPHONE or SWISSCOM. (The map from Advanced Authentication methods to OSP auth class type is NaafContractExecutable.METHOD_TO_TYPE_MAP.)
In this example, after the user is identified, if there is a chain available with the Smartphone or Swisscom methods, then the authentication proceeds. If not, the authentication fails and Advanced Authentication returns a no requested authentication context status to the Service Provider.
An optional Comparison attribute can be set on the <RequestedAuthnContext>. This attribute is defined in the SAML 2.0 Core specification in section 3.3.2.2.1.
In addition to requesting the Advanced Authentication methods using the SAML 2.0-defined URNs, Advanced Authentication also has a special contract parameters class reference URN. The URN is: urn:uuid:519a6c73-f092-43d3-ab11-8d789ebc2f79.
The contract parameters are added through the URN q-component. The URN syntax is defined at RFC 8141.
The <NaafEvent> contract executable contains attributes named allowClientChainSelection and allowClientEventSelection. These attributes allow the authentication chain and the authentication event to be selected through a contract parameter from the client, which in this example, is the SAML Service Provider. In the Advanced Authentication authcfg.xml, the default value of allowClientEventSelection is false and allowClientChainSelection is true.
For example, ISM is an event name with the following chains: LDAP+Smartphone, LDAP+SMS_OTP, LDAP+TOTP, LDAP+SecQuest, LDAP+U2F, and LDAP+Voice.
If the <NaafEvent> contract executable is configured with the ISM event, then the following code will request the LDAP+SMS_OTP chain.
<samlp:RequestedAuthnContext> <saml:AuthnContextClassRef>urn:uuid:519a6c73-f092-43d3-ab11-8d789ebc2f79?=internal.osp.oidp.aa.chain-name=LDAP%2BSMS_OTP</saml:AuthnContextClassRef> </samlp:RequestedAuthnContext>
The plus sign '+' is encoded as '%2B'. Advanced Authentication considers that the q-component, which starts with ?=, is in the x-www-form-urlencoded format and '+' is a reserved character for this syntax.
The two contract parameters that are defined in the Advanced Authentication class CFGNaafEvent are:
internal.osp.oidp.aa.chain-name
internal.osp.oidp.aa.event-name