You need to learn more about Bitcoin, I would say I will be quite worried about how you handle customers funds as you don't seems to understand what is a bitcoin wallet or exchanges.
I know what poloneix is. But i never have used it cause i have no interest in Cryptocurrency trading. I've lost my fair share with forex trading. And i have mentioned above this has nothing to do with the site. This question was asked to me by a friend and i just asked here.
And if it is crime to ask a simple question here then I am guilty as charged.
Common sense is telling us that you are holding funds in poloniex and that you want to sign message from there to prove size of your bankroll which is how much btc? And yet you say it has nothing to do with it...you confused people with off topic post.