HIP-16: Enforce a 6.4% max key per shard limit for each validator

[TrickLuhDaKidz]

This is from November. Leo is discussing too many keys per shard

Discussion: reducing BLS keys

I’ve noticed some big validators have more than 40 or 50 keys per shards. So, given one shard has 250 keys in total, it is about 50/250 = 20% of the keys in one shard. If 100% of the voting power is assigned to all external nodes, so if two of those big validator nodes in the same shard are doing maintenance and stopped the nodes at the same time, that shard will lose 40% of the voting power and the consensus will stop as consensus needs 67% of voting power to proceed. That’s the current risk b…