Rate Limiting Withdrawals

In order to protect against vulnerabilities or other exceptional scenarios, hashi will implement a Rate Limiter on out flows via the Guardian.

The limit will be a configurable value denominated in BTC and implemented as a token bucket rate limiter, that is capacity will be replenished continuously over a fixed duration.

When a user wishes to withdraw their BTC back to Bitcoin, they initiate a withdraw request. All withdraw requests are tagged with a timestamp of when the request was made and placed in a queue to wait for hashi to process the withdrawal.

In order to process a withdrawal request hashi will select a request from the queue and perform a number of checks, one of which is communicating with the Guardian to ensure there is sufficient capacity for the request. If all checks are satisfied and there is capacity, hashi will work with the Guardian to sign and broadcast a Bitcoin transaction to satisfy the request.

When a withdraw request comes in and it would exceed the rate limit, hashi will wait to process it until sufficient capacity is replenished.

Withdrawals will generally be processed in FIFO order, but this is not a strict requirement and there are some scenarios where they may be processed out of order.

User withdrawal requests can be canceled, by the Sui address that initiated them, anytime prior to hashi selecting a request for processing.