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Correction: pay $400/hr to gain a temporary majority in the block mining lottery. You can do a variety of things with that majority power, but “rewriting histor

Correction: pay $400/hr to gain a temporary majority in the block mining lottery. You can do a variety of things with that majority power, but “rewriting history” is a bit misleading. Yes, you can probably get the network to discard some previously accepted blocks, but this only allows you to invalidate your own transactions plus the transactions that depend on them. Furthermore, any blocks that were mined under high hashpower still need the same hashpower to be re-mined. A one-time reduction in network hash power doesn’t make previously mined blocks easier to mine.

jayd16 6y ago
Wouldn't you be able to buy goods, reverse the transaction, and buy more goods? That seems pretty significant if BTC is supposed to be ubiquitous (large transactions don't raise eyebrows) and cheap to use (meaning cheap to hash and cheap to takeover).
- jkhdigital 6y ago
  Depends entirely on the policies of the merchant from which you’re buying goods. I have to admit, I had to read a couple dozen research papers about (theoretical) attacks on Bitcoin before I really understood the nuances. I’m expecting main chain transactions to be relatively expensive, but off-chain solutions can still be cheap. Yes, this requires some trust of a third party, but for small transactions that’s probably unavoidable. Not all transactions are created equal, and trustless settlement is expensive.
qes 6y ago
Correction (where are you folks learning math? $400/hour, do you even have common sense?): 0.009 BTC/PH/day to buy from NiceHash (https://www.nicehash.com/algorithm/sha256 https://www.nicehash.com/algorithm/sha256) 100,000 PH/day total hashrate of BTC network (https://www.blockchain.com/charts/hash-rate https://www.blockchain.com/charts/hash-rate) That's 450 BTC/day to buy 50% of the hash rate (as if you even could, that in itself is a ridiculous notion - NiceHash says they have only 300 PH). Or 18.75 BTC/hour. Or $185,000/hour. Of course, you're not going to buy 50% of the network's currently running hash power. You'd likely need closer to 100% of the network's current hash power to gain 51%.

jayd16 6y ago

Wouldn't you be able to buy goods, reverse the transaction, and buy more goods? That seems pretty significant if BTC is supposed to be ubiquitous (large transactions don't raise eyebrows) and cheap to use (meaning cheap to hash and cheap to takeover).

jkhdigital 6y ago
Depends entirely on the policies of the merchant from which you’re buying goods. I have to admit, I had to read a couple dozen research papers about (theoretical) attacks on Bitcoin before I really understood the nuances. I’m expecting main chain transactions to be relatively expensive, but off-chain solutions can still be cheap. Yes, this requires some trust of a third party, but for small transactions that’s probably unavoidable. Not all transactions are created equal, and trustless settlement is expensive.

qes 6y ago

Correction (where are you folks learning math? $400/hour, do you even have common sense?): 0.009 BTC/PH/day to buy from NiceHash (https://www.nicehash.com/algorithm/sha256 https://www.nicehash.com/algorithm/sha256) 100,000 PH/day total hashrate of BTC network (https://www.blockchain.com/charts/hash-rate https://www.blockchain.com/charts/hash-rate) That's 450 BTC/day to buy 50% of the hash rate (as if you even could, that in itself is a ridiculous notion - NiceHash says they have only 300 PH). Or 18.75 BTC/hour. Or $185,000/hour. Of course, you're not going to buy 50% of the network's currently running hash power. You'd likely need closer to 100% of the network's current hash power to gain 51%.