Parses the IKE_INIT response packet received from Responder.

        Assigns the correct values of rSPI and Nr
        Calculates Diffie-Hellman exchange and assigns all keys to self.

def init_recv(self):
        """
        Parses the IKE_INIT response packet received from Responder.

        Assigns the correct values of rSPI and Nr
        Calculates Diffie-Hellman exchange and assigns all keys to self.

        """
        assert len(self.packets) == 2
        packet = self.packets[-1]
        for p in packet.payloads:
            if p._type == payloads.Type.Nr:
                self.Nr = p._data
                logger.debug(u"Responder nonce {}".format(binascii.hexlify(self.Nr)))
            elif p._type == payloads.Type.KE:
                int_from_bytes = int.from_bytes(p.kex_data, 'big')
                self.diffie_hellman.derivate(int_from_bytes)
            else:
                logger.debug('Ignoring: {}'.format(p))

        logger.debug('Nonce I: {}\nNonce R: {}'.format(binascii.hexlify(self.Ni), binascii.hexlify(self.Nr)))
        logger.debug('DH shared secret: {}'.format(binascii.hexlify(self.diffie_hellman.shared_secret)))

        SKEYSEED = prf(self.Ni + self.Nr, self.diffie_hellman.shared_secret)

        logger.debug(u"SKEYSEED is: {0!r:s}\n".format(binascii.hexlify(SKEYSEED)))

        keymat = prfplus(SKEYSEED, (self.Ni + self.Nr +
                                    to_bytes(self.iSPI) + to_bytes(self.rSPI)),
                         32 * 7)
        #3 * 32 + 2 * 32 + 2 * 32)

        logger.debug("Got %d bytes of key material" % len(keymat))
        # get keys from material
        ( self.SK_d,
          self.SK_ai,
          self.SK_ar,
          self.SK_ei,
          self.SK_er,
          self.SK_pi,
          self.SK_pr ) = unpack("32s" * 7, keymat)  # XXX: Should support other than 256-bit algorithms, really.

        logger.debug("SK_ai: {}".format(dump(self.SK_ai)))
        logger.debug("SK_ei: {}".format(dump(self.SK_ei)))