Monday, November 12, 2018

Mindset of an Attacker

Disclaimer: The post may be slightly biased against SV, but I'm aiming to keep a neutral tone. I'll be mostly quoting pro-SV organization SBI Crypto who are (to my knowledge) behind a very large portion of hashrate. The post is only intended to document what the strategy from SBI (and pro-SV) side is.

Thus, it should be informational for both sides and anyone else interested.


Intro

On 15th of Nov, there'll be a fork between the different BCH implementations. The implementations ABC, BU, XT, and Flowee are in favour of continuing with the BCH roadmap - while SV is in disagreement and wishes to push a different path.

Recently, SV has acquired a significant amount of hashrate, which you can check on the following URL: https://cash.coin.dance/blocks

On 30th of Aug, the new SV client was first announced by nChain, as well as a new miningpool to go along with it. ( https://news.bitcoin.com/nchain-publishes-bitcoin-sv-alpha-release/ )

The most prominent organizations that have been active in supporting the SV client have been Coingeek (mining pool & news site), nChain, and SBI Crypto (crypto division of biggest banking conglomerate in Japan).

To elaborate on how they plan to push SV client into fruition, I've visited the blog of Jerry Chan, the head of Crypto in SBI Bits (SBI Crypto). If you'd like to know more about him or SBI, you can check his previous interviews on Youtube, eg: https://www.youtube.com/watch?v=-nBEPCSrna8

His blogposts that I'll be referring to is found at: https://www.yours.org/@wallstreettechnologist


#1 - There can be no split

But wait, I thought the intent of 15th Nov fork is to conclusively split? Already from the blog title, we can see the following:

There can be NO SPLIT of BCH -- Or the network dies!

https://www.yours.org/content/there-can-be-no-split-of-bch----or-the-network-dies--d2541010f641

And the best way to completely avoid any splits, according to him, is to simply to always follow the "Longest Chain wins" rule.

What is this solution you ask? Simply, it is "Longest Chain wins" rule. Yes, the same rule that BCH violated in order to be forced into being.

… "LCw rule" simply punishes the minority side refusing to upgrade by putting ever increasing risk on the block rewards that they have earned until they lose it all, all the way back to the first block that they deviated from the majority from.

Furthermore, he very clearly states that future immutability is 100% a goal.

...it is time for BCH to show the world that a totally immutable, totally unsplittable global ledger is indeed possible.


#2 - The split between SV and ABC isn't about blocksize, it's about control & approach to forking

This, it seems is the reason why the BCH upgrade of Nov has become contentious; the fact that one side believes that the protocol should not hard fork unless absolutely necessary, and should never split the ledger, while the other side believes that hard forks should be regular and often, new features should be put into the protocol, and that splitting the chain into new coins is acceptable.

https://www.yours.org/content/who-gets-the--bch--ticker-after-a-contentious-fork--801770e75240

Also, while not directly admitting themselves of doing such, he does warn of "… the false narratives of different parties vying for political control during a fork upgrade." Of course, both sides can be guilty of this.

With all this kept in mind, perhaps this means that the SV vs ABC debate has never been about technical merits?


#3 - Minority chain will be killed, by mining empty blocks

https://www.yours.org/content/bch-upgrade-and-fork-mechanics-101---what-you-should-know-about-how-bc-6c4ba61cf099

In this article, he brings a very good board game analogy in tsumego from Go.

In the game of Go, tsumego in the concept that deal with the life-or-death of a group of stones.

... similarly, after a Nakamoto Event, the minority hash chain is not-alive until it can ensure that the majority hashpower chain cannot wipe out their chain with a reasonable amount of certainty

During a Tsumego Event, the fact is that as long as the side with the majority hash make the 'best move' there is nothing that the minority side can do to stay alive.

Life-or-death. Literally force the move to kill off the player that's at a disadvantage.

For example, in the upcoming upgrade, one side is introducing a changed called CTOR. This is a new rule which enforces a certain ordering of txns in a block. After the upgrade only blocks produced abiding by the CTOR rules will be deemed valid on this chain.

But one way (I'm sure there are many) that the majority chain can make their blocks valid is simply to support the feature but only for a day or two, long enough such that all the minority miners lose enough money so that they upgrade.

Here, he literally details out the planned attack vector for the SV fork. This actually lines up with another recent thread that warned about an empty block mining attack being a possibility.

A majority hashpower attacker can simply pretend to be running the same client (or version), for long enough to accomplish their attack, and to make the minority hashpower miners be forced to upgrade.


#4 - SV aims to keep the exchange ticker

https://www.yours.org/content/who-gets-the--bch--ticker-after-a-contentious-fork--801770e75240

Here, he strongly recommends of who has the most influence of keeping the exchange ticker. He plays down the influence of exchanges, wallets, developers and users.
The most important ones, according to him, are miners (hashrate) and the fork ID.

So if you (as a business) wanted to use the method in which the least amount of people would be able to dispute, the you would use a combination of method #5 and #6,

However, according to him, each of the contending forks will also attempt to keep the same fork ID

... because there actually potentially 2+ chains that will be using the original BCH fork ID, Bitcoin SV, Bitcoin ABC and what I will call Bitcoin Cash Classic

Thus, if SV has the majority hashrate, and aims to keep the same fork ID, while simultaneously attacking and trying to kill off any competing chains, SV could (according to the plan) even take over the BCH ticker.


It's a bit of a longer post, but I think it's important for both pro-ABC and pro-SV users to understand these perspectives.

The blog is very insightful and I honestly had to stop myself short of making the post too long. If the feedback is positive, I might feature more highlights from the blog in a "Part 2" post.

Cheers!


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