Back on 2.2.4 (or earlier?) on C7 I was able to add a ZEN25 on firmware 2 without any security by cancelling the popup screen asking about which securities I wanted during pairing, and then cancelling the following popup telling me about the zwave key. At least that's how I think made it add without security.
I'm trying to do the same, with the same hub (upgraded to latest firmware) with two new ZEN25. I can't get them to add with no security-- when I cancel those two popup windows, it still adds s2 unauthenticated.
I would think cancel would cancel the whole inclusion operation, not actually include with security enabled. Of course I am not sure this is possible due to the sdk.
Unchecking the security options and clicking ok would continue with the inclusion and no security.