RFC 7427 :
Basic pluto with IKEv2 using X.509 on the initiator (west), and Strongswan on
the responder (east) with impair.

Impairment is introduced in such a way that , the Signature hash notification is
not sent. Therefore Authentication method is no longer Digital Signature , but RSA (legacy)

This case is to be sure that libreswan without Digital Signatures(RFC 7427) ie an older version
can still interop with Strongwan (with Digital Signature implemented)


