Crack shard rotation

[linear]

The Demos network rotates the shard members for every new block. The shard members are also responsible for operating the bridges for that given block. When we elect a new shard for the upcoming block, we need to notify the tank contracts that the shard has changed (shard rotation). That way, the tanks can verify that withdrawals are being authorized by the current signers.

The problem: shard rotation requires a write transaction to the tank contract. These transactions are not free, and since they happen for every new Demos block (every ~10s) they are not economical. We would be loosing money to keep the bridges running.

Jeff and Cris have discussed several possible solutions to this problem, but so far none has fixed it without leaving a way to drain the tanks.

We think the solution lies somewhere along the lines of decentralized key generation and signing (DKG), but there's still some missing piece as far as verifications on the contract are concerned.

STATUS: RESEARCH-ONGOING