ConstUS_discloses_V2

If an active adversary controls Alice, force `us` always output `(1, 0)`, then the key privacy premise `v2 _|_ dotp2_rv us vs` is impossible. In contrast, if Alice is an fair player, the probability that `us` outputs that specific value `(1, 0)` is 1/m^2. Finally, if Bob enforce ZPK check to abort the protocol when that value is generated, `v2 _|_ dotp2_rv us vs` is guaranteed, and the protocol is secure with that mitigation ("security with abort") \cite[\S5.2]{dumas2017dual}. Therefore, here we examine the compromised case: `us = (1, 0) -> ~ v2 _|_ dotp2_rv us vs` and the secure case: `us != (1, 0) -> v2 _|_ dotp2_rv us vs`.