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Requesting authentication at a specific LoA

A SP can request authentication at a specific LoA by specifying that LoA in the AuthnRequest. Note that an SP can send an AuthnRequest to the gateway at any time, also when a user is already logged in at the SP. This allows an SP to raise the LoA depending on the context.

The requested LoA is seen as a minimum LoA. The Strong Authentication gateway can perform authentication at a higher LoA, in which case the higher level will be expressed in the returned SAML Assertion.

The requested LoA is passed to the Strong Authentication gateway in an AuthnContextClassRef element in a RequestedAuthnContext element in the SAML AuthnRequest:

RequestedAuthncontext 
<samlp:RequestedAuthnContext>
    <saml:AuthnContextClassRef>http://surfconext.nl/assurance/loa2</saml:AuthnContextClassRef>
</samlp:RequestedAuthnContext>
AuthnRequest with a request for authentication at LoA 2 
<samlp:AuthnRequest xmlns:samlp="urn:oasis:names:tc:SAML:2.0:protocol"
                    xmlns:saml="urn:oasis:names:tc:SAML:2.0:assertion"
                    ID="_ace040cdf97c2efba5aa4d973a32318217b9aaae09"
                    Version="2.0"
                    IssueInstant="2014-05-26T06:47:27Z"
                    Destination="https://sa-gw.surfconext.nl/authentication/single-sign-on"
                    >
    <saml:Issuer>http://test-sp.example.com</saml:Issuer>
    <samlp:RequestedAuthnContext>
        <saml:AuthnContextClassRef>http://surfconext.nl/assurance/loa2</saml:AuthnContextClassRef>
    </samlp:RequestedAuthnContext>
</samlp:AuthnRequest>

 

All AuthnRequest messages must be signed by the SP using SHA-2. The HTTP-REDIRECT binding must be used to submit the request: the signature is put in HTTP request parameters (no XML-Signature is used).

Authentication failure

When authentication fails, it is generally because the user:

  1. cancels authentication during verification of the second factor or
  2. does not have a suitable second factor identification.
User cancels authentication 
 <samlp:Response xmlns:samlp="urn:oasis:names:tc:SAML:2.0:protocol"
                xmlns:saml="urn:oasis:names:tc:SAML:2.0:assertion"
                ID="_Yasz/Kubip05bTwe7hIWOc5As+NxwmEliPJ88nUQ"
                Version="2.0"
                IssueInstant="2015-05-12T12:17:38Z"
                Destination="https://your-sp.example.com/acs-location"
                InResponseTo="_6d93f735ccfb8d98454999b4016d515834211b0dde"
                >
    <saml:Issuer>https://sa-gw.surfconext.nl/authentication/metadata</saml:Issuer>
    <samlp:Status>
        <samlp:StatusCode Value="urn:oasis:names:tc:SAML:2.0:status:Responder">
            <samlp:StatusCode Value="urn:oasis:names:tc:SAML:2.0:status:AuthnFailed" />
        </samlp:StatusCode>
    </samlp:Status>
</samlp:Response>
User does not have suitable second factor identification 
 <samlp:Response xmlns:samlp="urn:oasis:names:tc:SAML:2.0:protocol"
                xmlns:saml="urn:oasis:names:tc:SAML:2.0:assertion"
                ID="_Yasz/Kubip05bTwe7hIWOc5As+NxwmEliPJ88nUQ"
                Version="2.0"
                IssueInstant="2015-05-12T12:17:38Z"
                Destination="https://your-sp.example.com/acs-location"
                InResponseTo="_6d93f735ccfb8d98454999b4016d515834211b0dde"
                >
    <saml:Issuer>https://sa-gw.surfconext.nl/authentication/metadata</saml:Issuer>
    <samlp:Status>
        <samlp:StatusCode Value="urn:oasis:names:tc:SAML:2.0:status:Requester">
            <samlp:StatusCode Value="urn:oasis:names:tc:SAML:2.0:status:NoAuthnContext" />
        </samlp:StatusCode>
    </samlp:Status>
</samlp:Response>
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