OK you risk sharing the key with them and this is just what I thought Coinbase was doing and Coinbase even give you
the public key to maintain the illusion but when you check the public address in the block-chain you then realize it's a
scam and the coins come from a pool account and for all we know they are fake.
I love the API's blockchain.info offers to developers so yes your plan sounds right to me and I think they can
be trusted unlike Coinbase who even scammed me out of the $10 joining fee, keep away from them, bad news
Coinbase also shares information of our bitcoin transfers with IRS, and IRS with other national governments. Keep away from them (x2).