3 ms·
"Even in a worst case scenario, if a government or some other anti-Bitcoin faction gets a hold of greater than 50% of the processing power (an extremely expensi
by gst 15y ago
"Even in a worst case scenario, if a government or some other anti-Bitcoin faction gets a hold of greater than 50% of the processing power (an extremely expensive feat, and hardly worth it unless you're really determined to destroy the network), the rest of the network can be reconfigured to reject that block chain."
At this point the author shows that he does not have much technical background in regard to the Bitcoin network. Once an adversary gains >50% of the processing power you have basically lost. Yes - you can manually blacklist a single "fork" of the blockchain, but the adversary can fork as often as he wants and you cannot immediately tell if a new block has been generated by the adversary.
- gasull 15y ago> Once an adversary gains >50% of the processing power you have basically lost. Wrong. An attacker having more than 50% of the network would just stop payments until the rest of the network rejects the attacker nodes. https://en.bitcoin.it/wiki/Weaknesses#Attacker_has_a_lot_of_computing_power https://en.bitcoin.it/wiki/Weaknesses#Attacker_has_a_lot_of_...
- gst 15y agoYou can't "reject attacker nodes". There is nothing in the blockchain that identifies a given miner.
- gasull 15y agoI've seen pie charts with the computing power of several mining pools and the total. I believe you can find the IP of a miner that has a lot of computing power.
- gst 15y agoIf there's a public mining pool it's easy to estimate it's computing power. Just take part in the mining pool and compare your own computing power with the percentage of the 50 BTC that you get for each block. Or, alternatively, you can track the BTC that you get from the mining pool back to the block where they were generated, and so you know that this block must have been generated by the mining pool (again, allowing you to use the amount of blocks generated by the mining pool to estimate it's overall computing power). However, if the attacker does not use a public mining pool, but private infrastructure, things get more complicated: The only way how Bitcoin clients can agree on a common view of the block chain is to treat the highest block number as the authoritative one. A malicious miner can now just generate new blocks and inject them over Tor to some of the Bitcoin nodes. As Bitcoin nodes distribute the blockchain amongst each others, those "malicious" blocks will quickly spread throughout the Bitcoin network. The only way how you could prevent this problem is some kind of whitelisting approach, where miners need to be manually approved before their blocks are accepted. However, this would totally change the current Bitcoin infrastructure and turn a completely decentralized network into a more centralized one.
- gasull 15y agoThis is very interesting. Thank you for the info. I think a solution to this attack would be a web of trust, like PGP/GnuPG works for verifying signatures.
- weavejester 15y agoRight. In fact, it's hard to imagine any network working if over 50% of the power rests with users who are trying to subvert or destroy the system.