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With enough political or legal pressure, you easily deploy a "51% attack" on the chain, and fork it as you like. Just as the NSA runs almost all the Tor exit n

With enough political or legal pressure, you easily deploy a "51% attack" on the chain, and fork it as you like. Just as the NSA runs almost all the Tor exit nodes nowadays, what would stop a government from running the majority of blockchain nodes and gain consensus majority?

sparkie 8y ago
> With enough political or legal pressure, you easily deploy a "51% attack" on the chain, and fork it as you like. A 51% attack can do two things: Enable "double-spend" attacks - where the hash rate majority will ignore a block which was previoulsy mined and had a "confirmed" transaction, and instead mine from an older block which didn't have that transaction - but instead place a transaction paying themselves the money back. Anyone accepting payments over Bitcoin should use their common sense as to how many confirmations they should wait depending on the amount of money being transmitted. A 51% attack might eventually be able to write a chain longer than the current one, but it will take some time - and there is the chance that if it fails, the miner will have wasted his electricity costs. The other attack a 51% hash power can perform is denial-of-service. They can ignore blocks containing transactions they do not want to include in the chain, and as long as they continue to mine the longer chain, those transactions will not succeed. 51% attacks can not change the rules of Bitcoin (although there are many people who wrongly believe this to be the case). If you try to change the rules, the rest of the network will reject your blocks and ignore you. > what would stop a government from running the majority of blockchain nodes and gain consensus majority? The costs, primarily. In the case that one party did accumulate a majority of hashing power, the network participants can agree to change the hashing algorithm to one which runs on commodity hardware. That would be many billions of dollars of specialized hardware equipment going down the drain, and will only make the system stronger by encouraging individual participation. Monero did this successfully, and plans to do it each 6 months to deter attempts to game their proof-of-work.

sparkie 8y ago

> With enough political or legal pressure, you easily deploy a "51% attack" on the chain, and fork it as you like. A 51% attack can do two things: Enable "double-spend" attacks - where the hash rate majority will ignore a block which was previoulsy mined and had a "confirmed" transaction, and instead mine from an older block which didn't have that transaction - but instead place a transaction paying themselves the money back. Anyone accepting payments over Bitcoin should use their common sense as to how many confirmations they should wait depending on the amount of money being transmitted. A 51% attack might eventually be able to write a chain longer than the current one, but it will take some time - and there is the chance that if it fails, the miner will have wasted his electricity costs. The other attack a 51% hash power can perform is denial-of-service. They can ignore blocks containing transactions they do not want to include in the chain, and as long as they continue to mine the longer chain, those transactions will not succeed. 51% attacks can not change the rules of Bitcoin (although there are many people who wrongly believe this to be the case). If you try to change the rules, the rest of the network will reject your blocks and ignore you. > what would stop a government from running the majority of blockchain nodes and gain consensus majority? The costs, primarily. In the case that one party did accumulate a majority of hashing power, the network participants can agree to change the hashing algorithm to one which runs on commodity hardware. That would be many billions of dollars of specialized hardware equipment going down the drain, and will only make the system stronger by encouraging individual participation. Monero did this successfully, and plans to do it each 6 months to deter attempts to game their proof-of-work.