The user can log in and decrypt their root key, loading it in the secure HTML+JS environment.
Given a root key, the user can create and manage unlimited accounts as children of that key, in order to share the address with others. The private key to sign transactions on behalf of that address would be derived from the root key, in the standard way described in the links above.
The interface would make it so that the root key can show the total amount spread out across the child addresses and balances, but can also be expanded to see all the addresses, and their local nicknames.
Anyone who doesn't have the root key would not be able to correlate the child keys / addresses with each other from just their on-chain information, rendering the accounts effectively pseudonymous. However, they will be able to see transactions involving these addresses, and the provider may also see the IP address, etc.
Background
Read these two links:
What to do
We want to include code from https://www.npmjs.com/package/hdkey in our client-side HTML + JS page.
The user can log in and decrypt their root key, loading it in the secure HTML+JS environment.
Given a root key, the user can create and manage unlimited accounts as children of that key, in order to share the address with others. The private key to sign transactions on behalf of that address would be derived from the root key, in the standard way described in the links above.
The interface would make it so that the root key can show the total amount spread out across the child addresses and balances, but can also be expanded to see all the addresses, and their local nicknames.
Anyone who doesn't have the root key would not be able to correlate the child keys / addresses with each other from just their on-chain information, rendering the accounts effectively pseudonymous. However, they will be able to see transactions involving these addresses, and the provider may also see the IP address, etc.