You saying broker here is what I am trying to comprehend. Do you mean an exchange, escrow, mixer or what? As this is a Crypto platform, you saying about broker means you are referring to forex  which does not align with our activities here in anyways. For your quick understanding, there are centralised and decentralized exchange for which you can buy and sell your Crypto assets and also you can trade on Crypto currencies there too. Then for am escrow, you can contact any reputable member here to stand in for you for transparency and credibility. There are lots of exchange online there that can you can find reliable based in their reviews but Do Your Own Research.