What made me change my mind about Zcash

[nullius]

@tokidoki, with apologies for the double-reply, this is such a pivotal point that I wanted to circle back to it after batting out a quick reply earlier:

@tokidoki

I don’t get how proponent of POW keeps saying POS promotes “rich get richer” while in POW, only the rich can mine the coin. Even owning a gaming GPU is hard for over 90% of world internet users and now you force everyone to buy cartel-produced ASICs if they want to participate in providing network security?

Out of many arguments against POS (including corrupt economics/financial manipulation), my biggest argument is that the only POS “validators” who participate in providing network security are staked nodes. Even POS language is exclusionary towards those who are relegated to mere “observer” status.

I do not speak from ignorance of POS. I have direct experience in POS-land, I have studied the technical aspects of some POS coins, and I know people deeply involved in POS business. I also saw up close what happened recently with the Terra hardfork: A group of DPOS companies colluded to hardfork the Terra chain by executive fiat, over massive community opposition. High capital rules the day.

In Bitcoin and Bitcoin-like Nakamoto Consensus coins, every full node, including every non-mining node provides network security. Every full node is a “validator”!

I am a veteran of that debate. And the theories that I expound were brilliantly proved in practice in 2017. In particular, on 2017-11-12, I personally watched as miners attempted “flippening” Bitcoin in a hostile takeover. Their declared intent was to kill off the BTC mainnet, and force everyone to switch to BCH. They only succeeded in moderately degrading Bitcoin’s performance for a short time.

It is for this reason that Bitcoiners are fanatical about getting people to run inexpensive full nodes. For one of innumerable examples that I have seen, this recent forum post by gives instructions for “How to run a Bitcoin Core full node for under 50 bucks!” Subhead: “Everyone should have the opportunity to run a node.” That is for people who “want to participate in providing network security”, as you put it.

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Insofar as reasonably practicable, I wish to show that I am not only saying this now. From my history as nullius elsewhere, please see this post that I made 2018-02-04 (yes, this was given “merit” by Greg Maxwell; all italics and boldface are in the original):

Miners have one, only one, and exactly one job: To provide the ordering of transactions in a Byzantine fault-tolerant manner (which in turn prevents double-spends). That’s what miners do. That is all miners do. Granted, it is an important and resource-intensive job; that’s why miners get paid for it. But that is the one and only security function of miners.

Of course, miners must validate each block they produce; if they didn’t, they would be unable to reliably produce valid blocks. But miners are not the parties responsible for enforcing validation on the network. Full nodes do that. Each individual full node does that, so as to provide better security for its owner; and all full nodes collectively do that, thus providing validation security for the whole network. Observe how here as everywhere, Bitcoin precisely aligns the individual’s selfish interest with the common good.

Full nodes do not blindly “follow the longest chain”. They follow the chain independently validated by them which has the highest total POW. A miner (or 51+% of miners) who produced invalid blocks would only be wasting hashrate, and likely risking widespread blacklisting of IP addresses. It doesn’t matter if the invalid blocks steal money from Segwit transactions, steal money from old-style transactions, create 21 billion new coins, or are filled with gibberish from /dev/random. An invalid block is an invalid block, and shall be promptly discarded by all full nodes—period.

See also the footnote to this post from 2017-12-04—one of the first posts I made on the Bitcoin Forum, even though I created the account there the same day as my account here:

Miners have exactly one function: Byzantine fault-tolerant ordering of transactions. Important and valuable though that function may be, it is strictly limited in technical scope. Miners do not have authority over validation: All full nodes are responsible for enforcing validation, and will reject invalid mined blocks just as if rejecting random garbage. Such is the power of each and every individual full node.

I advocate that Zcash should follow the same model. I also wish to urge ECC to optimize and reduce full node resource requirements. This is partly self-interested, because I run, and have always run zcashd on weak, underpowered hardware.

If you want everyone everywhere in the world to be able to run zcashd, without discrimination on the basis of wealth or access to fancy hardware, I can tell you from experience where the pain points are—for example, my node is currently stuck partly due to a performance issue that I noticed is already ticketed in GH. :-\ I have had many such issues with Zcash, over the years; and in Sprout, shielded send took not “30–40 seconds” as advertised, but minutes of spinning my machine at full throttle. I endured that, because I care about privacy—I demand only the best privacy!