COMIT application expiry constraints

[da-kami]

Problem

There is currently no spec for the expiry handling in COMIT. Even though COMIT can come up with default expiries, they are only safe under the assumption that the application takes the constraints that are used to come up with the expiries into consideration.

Goal

Be able to build applications on top of COMIT in a secure way.

Proposal

Specify where:

Update the security section in https://github.com/comit-network/RFCs/blob/master/RFC-003-SWAP-Basic.adoc#security-considerations

Specify what:

Given an asset pair, the default expiries are calculated as X time-units for Alice and Y time-units for Bob because of constraints Z (e.g. underlaying ledger constraints). An application on top of COMIT has to ensure that the redeem transaction is done in due time according to the calculated expiries (X for Alice and Y for Bob).

Additionally add some guidelines for achieving this, e.g. for Ethereum adapting the gas price according to the current network constraints, suggest using metamask or https://www.ethgasstation.info/

[thomaseizinger]

Given the outcome of comit-network/comit-rs#1552, the recommendation would be to make this a spike.

[bonomat]

I think we can remove the blocking from comit-network/comit-rs#1530.