I have an app in which users deposit bitcoins to increase their credit in the website to have access to some specific stuff. So the way I'm thinking to implement this is by using an HD wallet in which I'll have my master keys to myself and generate a child address for each user that signs up and if they send bitcoins to their addresses, their credits will be increased.
The problem is that how can I manage and access all bitcoins with the master keys. thanks in advance.
These are not separate Accounts in any bitcoin related sense.
Your back end database website will need to track the public address assigned to each user, and their contribution transaction history, amount and date (fiat equivalent?) as well as a total per user.
Any HD wallet will let you manage the coins, spend with private keys, show your running total balance etc
It may also manually generate batches of new addresses for you to import into your back end database website, ready to assign to new users signing up
say a hundred at a time?
If that get tedious, then your back end database website will need to incorporate that functionality, only needs the public keys for generating new addresses,similar to a watch-only wallet.
Be sure to use the HD address hardening feature, limit the damage if a hacker gets your public keys.
