A user sends hbar to the custodian’s address (fireblocks). Upon receiving, the custodian party (hbar.com) will mint corresponding wHBAR tokens, taking fees for management (30 bps) and gas fees (determined at run time).
A user signals a burn TX using the user interface and submits a real Ethereum TX. Upon hearing the TX, the custodian party’s server will record it, and call the TX to initiate the withdrawal process. Specifically, the user’s wHBAR is transferred to a suspense account where it is held until the HBAR is paid. Once the HBAR is paid, the suspended wburned. There is also a 30 bps fee on the burn in addition to the ethereum gas fees.