[Consensus] Write-up rationale for VDFs in EC

[sternhenri]

What it is
This could take a number of formats (GH comment below, doc, etc), but it simply seeks to rationalize in a single artefact why EC needs VDFs. This includes arguments about:

• PoS replication of PoW guarantees (specifically for SPC)
• Potential attacks that are mitigated by VDF

Why it matters
This is a question we keep discussing, having this para could help generally onboard or level people up/track our thinking.

[sternhenri]

@ZenGround0 feel free to close if you no longer feel this is useful.

[ZenGround0]

Hey I know this is closed which is fine by me as I don't think this is launch blocking. But for more info on this topic see this issue in the archived aq repo.

[sternhenri]

Thanks @ZenGround0 I closed it for the reason you point out and the fact I think we have adequately aligned as a research team on why we want VDFs. For quick summary (I will provide longer write up in a forthcoming paper):

VDFs allow us to:

• Get rid of clock synchrony assumption that most consensus algorithms make, by effectively enforcing clock synchrony through waiting.
• Prevent folks from simulating the chain in the past (useful for a series of attacks), aside from the entropy provided by multiple participants on the chain
• Likewise prevent ticket grinding in running leader election, ensuring that elections remain power based rather than compute based (as one might by grinding through tickets in parallel)
• Prevent miners from rushing the protocol, thereby hurting miners who have worst connections and impacting protocol fairness.