Improve Withdraw Process

[boolafish]

Background

Our current design requires two step withdraw to protect venue/exchange on generating proof.

Description

As a user, I want the process to be simpler, so that I don't need to click the button twice to withdraw my money from exchange.

As a venue, I want to make sure user won't take move away the money while I am generating proof So that I do not need to take the risk and cost of re-generating proof unexpectedly.

Successful Criteria

• Ideally Simplify the withdraw process.
• Or, provide reason why the current process is the best one and list down the options we have and decide on which trade-off we are willing to take.

Notes

A sub story of #53.

[boolafish]

[note] Some ideas:

1. Two path of withdrawal:
   • happy path trader get venue's signature, and the withdraw happens directly without waiting.
   • Still support two phase withdrawal in case venue is framing
2. One edge case: A trader notifies and wait N blocks. However, before he submits the withdrawal execution tx, venue submits the trade tx. Talked with Pepesza, probably better to consider this same as order cancelation. Just let it pass anyway.

[boolafish]

Analysis: (Trader, Venue, Operator) -> result (o, o, o) --> : ) (x, o, o) --> Need two phase withdrawal or need venue's signature and would not work (o, x, o) --> Trader do two phase withdrawal on plasma chain. (PS. one edge case is described in previous comment.) (o, o, x) --> Venue IFE the last settlement (x, o, x) --> Operator let invalid withdraw (not waiting enough period) pass through, venue waste the cost of generating last trade proof. However, the withdrawal exit could be challenged so trader gets nothing. A lose-lose situation.

[boolafish]

Having two paths for withdrawal might be the best we have, closing this.