A problem with this mechanism is that proposals are public so validators can steal the contents of the packages without rewarding proposers. Below is another scheme.
Construction
- Anyone can propose unsigned collation headers, keeping the corresponding collation bodies secret
- Each unsigned collation header has a guaranteed proposer’s fee paid by the proposer to the validator if:
- Signing: The collation header is signed by the validator
- Inclusion: The signed collation header is included in the VMC in the validator’s period
- Exclusivity: The signed collation header does not conflict with another collation header in the validator’s period
Notes
- Validators sign collation headers without full knowledge of the collation bodies, and facilitate the inclusion of the signed collation headers in the VMC.
- The market of collation proposals effectively becomes an open auction, similar to transaction fees today.
- Proposers are responsible to collect coinbase rewards and transaction fees (including out-of-band transaction fees). They don’t have to disclose this revenue to proposers.
- Validators get the “lump” proposer’s fee without worrying about transaction fees. This aggregation service is nice for validators because transaction fees will be micro-fees spread out across shards and asset types (account abstraction allows to pay non-ETH transaction fees).
- Proposers are responsible for data availability of the collation bodies after the collation header is added to the VMC. In particular, the validator’s fee is paid even if the collation body is not properly made available by the proposer.
- Validators get paid even if the collation header gets orphaned. Individual proposers follow their own preferred fork choice rules when making proposals, and take on the corresponding orphanage risk.
- Validators can still have some say as to what goes in the collation bodies. For example, they can request particular transactions to be included and the proposers can provide Merkle proofs of inclusion alongside the proposals.