Require minimum number of shares in order to proceed in web app

We are putting together a contest of sorts, and are planning on integrating Facebook sharing as a method of proceeding deeper within the website as a qualification for entry into the contest.

The concept as pitched by the client involves a typical share button with popup box, where the user picks who they wish to share with. However, they want to require a minimum of 12 shares.

Firstly: "Is this even possible?"

Secondly: How might we go about validating that a given user actually shared the required number of people, or that the shared at all?

I imagine there might be a way to redirect them to the landing page after the sharing procedure some开发者_StackOverflow社区how. We're still trying to wrap our heads around this process and if it is even doable the way they want.

I think Chris Jester-Young's response was probably sufficient. Doing this is a bad idea and we spoke to the client this morning and got part of the contest changed. Thanks for at least speaking up about it, as I wasn't sure if what we wanted was even doable the way we were thinking.