Hello,
I and a friend are trying to develop an exchange, at last to learn how it works.
At moment, we are using bitcoinjs-lib.
1) An exchange creates a wallet per user ? Or does it have a single wallet which makes all transactions ?
2) If the exchange keeps a wallet per user, how can it protect the user's private key in case of unauthorised access in database ? Crypt and decrypt it with user's password is an option, but it implies in ask for password every transaction.
Regards,
1). No, exchanger has cold wallet and hot wallet. BUT. This wallets can hold many pairs "address-private key". Exchange creates many addresses (for every deposit transaction). But this addresses locates in cold wallet. Exchange give to you only voucher and in fact you don't own your money.