Stealth confidential wallet "transfer_from_blind" adds fee twice...

[jcalfee]

The fee code surrounding wallet_api::blind_transfer_help (calls to and internally) is confusing. I believe in one case the user pays double fees.

double fee case

wallet_api::transfer_from_blind adds the fee to the amount

auto blind_in = asset_obj->amount_to_string( from_blind.fee + amount )

and passes this to wallet_api::blind_transfer_help where later the change amount is found by getting the fee subtracted out twice (so they appear to be paying a double-fee). The first is the "amount" that contains the fee and the second is the fee itself:

auto change = total_amount - amount - blind_tr.fee

Note, there is another call to blind_transfer_help which is not subtracting fees first.

Related #452

[bytemaster]

James was going to produce a pull request with the suggested fix.

[jcalfee]

Not an issue..