currently I am creating/sharing an own crypto currency. Details about it are that it is a Scrypt Coin with Proof-Of-Work. But that's not really the question.
I will build a website around the coin and want to make users be able to create transactions without that their private key / wallet gets into my wallet (the websites wallet). For example I could create new wallets each time a user registers and show the private key with dumpprivatekey and RPC. But I want to make them to be able to make transactions with just entering their privatekey but without my website saving it or even their address later would be in the projects wallet. Best example for this is myetherwallet.com. Users enter their private key but the only location where this is saved is in an cookie on the users computer, not the website or any server of them itself. I hope you understand what I mean.