* Support RequestedAuthnContext
This implements limited support for RequestedAuthnContext by :
- Allowing SP administrators to define a list of authnContextClassRef
to be included in the RequestedAuthnContext of a SAML Authn Request
- Veirifying that the authnContext in the incoming SAML Asertion's
AuthnStatement contains one of the requested authnContextClassRef
- Only EXACT comparison is supported as the semantics of validating
the incoming authnContextClassRef are deployment dependant and
require pre-established rules for MINIMUM, MAXIMUM and BETTER
Also adds necessary AuthnStatement validation as indicated by [1] and
[2]
[1] https://docs.oasis-open.org/security/saml/v2.0/saml-core-2.0-os.pdf
3.4.1.4, line 2250-2253
[2] https://kantarainitiative.github.io/SAMLprofiles/saml2int.html
[SDP-IDP10]
b2e48c9fa7