Regardiing exposing the options of<md:EncryptionMethod in metadata

[Kalpa2019]

Hi All,
Recently, i got to work wiht Shibboleth idp, i was trying out with basic metadata configuration.
however, at the shibboleth idp, they had some relay/nameid configurations to encrypt always.
so, if authnrequest has been made, it was rejecting saying encryption parameters are not right.
but, encryption data was there, finally, adding the encryptionmethod along with the certificate worked.
it makes sense, because, they want to know what is the encryptionmethod(algorithm) supported. having this along with "use"=encryption options, have worked.
so, i wanted to inform that, it is very simple change, can I check-in the code. the code list all the encryption lsited in constatnts.py and updates to the meatadata in metadata.py.
if i update, what is the criteria. and mechanism. lke creating a branch, review and merget?

thanks,
Kalpa.

[pitbulk]

HI @Kalpa2019, sorry for the delayed reply

is not very common the need of encrypting in the SP side, at the end, no confidential data is sent on AuthNRequest, LogoutRequest and LogoutResponses, with the exception of the NameId, but you could use persistent NameID to anonymize the user.

That said, if I'm not wrong you want to expose the md:EncryptionMethod in addition to the ds:KeyInfo when md:KeyDescriptor has use="encryption".

For that I believe we need to extend the Metadata builder to support an additional parameter encryption_method=None
and then extend as well the methods _add_x509_key_descriptors and add_x509_key_descriptors and inside it, have something like:

cls._add_x509_key_descriptors(sp_sso_descriptor, cert, False,encryption_method)

and:

@staticmethod
def _add_x509_key_descriptors(root, cert, signing, encryption_method):
    key_descriptor = OneLogin_Saml2_XML.make_child(root, "{%s}KeyDescriptor" % OneLogin_Saml2_Constants.NS_MD)
    root.remove(key_descriptor)
    root.insert(0, key_descriptor)
    key_info = OneLogin_Saml2_XML.make_child(key_descriptor, "{%s}KeyInfo" % OneLogin_Saml2_Constants.NS_DS)
    key_data = OneLogin_Saml2_XML.make_child(key_info, "{%s}X509Data" % OneLogin_Saml2_Constants.NS_DS)

    x509_certificate = OneLogin_Saml2_XML.make_child(key_data, "{%s}X509Certificate" % OneLogin_Saml2_Constants.NS_DS)
    x509_certificate.text = OneLogin_Saml2_Utils.format_cert(cert, False)
    key_descriptor.set("use", ("encryption", "signing")[signing])
    if encryption_method:
        encryption_method_data = OneLogin_Saml2_XML.make_child(key_descriptor, "{%s}EncryptionMethod" % OneLogin_Saml2_Constants.NS_MD)
        encryption_method_data.set("Algorithm", encryption_method)

Do you want to contribute with a PR, if so please add as well test coverage.