Bitcoin’s Technical Flaw | Hacker News Reader

Bitcoin’s Technical Flaw

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10 pointsnanzhong7 comments

This reads like an ad for a closed source messenger only available in a few countries. Have no idea how its related to bitcoin. Clicks perhaps?

I have plenty of criticisms for bitcoin and cryptocurrencies in general but some of the claims here are amazingly absurd.

Note to author: I have used a bitcoin wallet with no troubles in China, it has better uptime in the last decade than Amazon where you worked with "distributed computing systems", can your messenger app do the same?

> just imagine that the Great Firewall blocks Bitcoin packets for a week, creating a Chinese fork and non-Chinese fork. Then it unblocks. All of a sudden, the non-Chinese fork would disappear. The Bitcoins that went into your wallet six days ago would vanish

The fact that the author doesn't understand how wrong this is despite apparently studying Bitcoin as an AWS employee back in 2010 is scary.

I am the author. I'd love to understand your point. Can you give specifics? Thanks.

You essentially point to a very large reorganisation and say all the tx's on the global chain will disappear once the GFW opens up again. All orphaned transactions go back in the mempool as unconfirmed and will be processed later.

Simply blocking all global traffic already creates a huge monetary incentive for miners to sidestep the rules and it's easily achieved with obfuscated transports.

Such an action would be noticeable and considered hostile. Were they causing network disruption you'd likely see a hardfork to memory hard algorithms or clients blocking Chinese IP ranges.

There's certainly attacks they could try but I'm not convinced of the effectiveness. Miners need the outside world to pay their bills as exchange for RMB is impossible.

Yes, you can put the orphaned transactions back in the mempool to be processed again. But what if the Bitcoins in those transactions are already spent on the "winning" fork? Does it now mean that the wait for a transaction to be considered "confirmed" needs to be longer the conventional six blocks and potentially arbitrarily long?

China already banned non-state sanctioned VPNs in 2018. Anyone circumventing the Great Firewall via "obfuscated transports" could get into legal trouble by the Chinese authority. The Chinese government successfully suppressed all dissidents and millions of protesters in 1989. Underestimate its force at your own peril.

The whole point of the article is that a centralized entity (the Chinese government) may be able to attack Bitcoin without controlling any mining power. A hard fork in response to actions of a centralized entity could shatter people's confidence in Bitcoin's promise of being decentralized. Blocking Chinese IP ranges in a 100% reliable way is going to very difficult. This defense is also rendered useless if someone does use a VPN to propagate the Chinese fork (perhaps intentionally by a centralized entity).

I read the whole post and did not get that impression. I thought it was a pretty good write-up explaining the concept of a “partition attack” on Bitcoin (and in distributed systems in general). I had not previously been aware of this form of attack.

Sure the author linked to his service, but I believe the intent was to show that if a government could recognize the signature of encrypted traffic and block it, then it would only be easier to block portions of bitcoin transactions.

Which ultimately paves the way for a bad actor to block large portions of external transactions, while allowing local transactions, then unblock transactions, which given a sufficiently large control of the network could “undo” other external transactions, in what was described as a partition attack. Thus ultimately result in the loss of trust in Bitcoin.

>If the Great Firewall blocks Bitcoin packets, the Bitcoin network would be partitioned and thus fork. Upon unblocking, the shorter Bitcoin chain would be wiped out. Ignoring complicated attacks, just imagine that the Great Firewall blocks Bitcoin packets for a week, creating a Chinese fork and non-Chinese fork. Then it unblocks. All of a sudden, the non-Chinese fork would disappear.

Is that true? Is it only based on how long the fork's chain are?

The Bitcoin protocol resolves conflicting forks by choosing the longer one while dropping the shorter one.

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