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On 9/13/2014 4:52 PM, Boussac wrote: > Hello, > > If the hashing power of the attacker is in the order of 50%, then > he can disrupt the network in several ways, including > double-spending and the blackout attack you are describing. > > Bitcoin makes only the assumption that there is a majority of > honest node. If you break the assuption, you disrupt the network > for as long as the assumption is broken. > > Back to your question, If the hashing power of the attacker is in > the order of 10%, the average time interval between blocks is > increased by 10%, i.e 1 minute when he pulls out of mining. > > That is until the next difficulty adjustement, roughly 2 weeks and > 36 hours later. Hardly a "blackout". > Indeed, but the scenario changes if the power is 80% if the hashing power. If immediately after a difficulty adjustment the hashing power drops by 80%, it will take way lot longer until the next difficulty adjustment. The next 2016 blocks will be solved much much slower preventing the correct functionality of the network, regardless if all the remaining peers and miners are honest. This is what matters, an assumption of this type of attack but with > 60% of the hashing power - 10% won't do a lot of damage and hardly create a blackout as you say. > Pierre > > Le 13 sept. 2014 à 15:15, s7r <s...@sky-ip.org> a écrit : > > Hi there, > > I have an contradictory discussion with an altcoin supporter and > want to bring some solid arguments in a public talk, so require > little help to respond to a question with simplest answer. > > The problem is within the difficulty adjustment mechanism, that it > happens at every 2016 blocks. In case the hash power will suddenly > decrease, the 2016 blocks will take a lot of time to solve, > therefor freeze the network in a non-operational way. I know by far > this is just a joke, because this is very unlikely to happen > anytime (people paid for mining equipment and make money) but for > the sake of discussion, let's just assume it 'could' happen. > > Can this really freeze the network for unlimited time and bitcoin > has no mechanism to balance it back? A resourceful party with the > intent to attack the network in an irrational way, brings lot of > hashing power and keeps it for 2016 blocks, then removes it leaving > the other 2016 blocks to solve at very high difficulty but with low > hash power in the network causing a 'blackout'? Thank you in > advance for your answers. > > >> >> ------------------------------------------------------------------------------ >> >> Want excitement? >> Manually upgrade your production database. When you want >> reliability, choose Perforce Perforce version control. >> Predictably reliable. >> http://pubads.g.doubleclick.net/gampad/clk?id=157508191&iu=/4140/ostg.clktrk >> >> _______________________________________________ >> bitcoin-list mailing list bitcoin-list@lists.sourceforge.net >> https://lists.sourceforge.net/lists/listinfo/bitcoin-list > -----BEGIN PGP SIGNATURE----- Version: GnuPG v2.0.22 (MingW32) iQEcBAEBAgAGBQJUFGiuAAoJEIN/pSyBJlsRDGgH/RMuUUHJw7rMlDzOWF9qNzpQ UgNBzqqwRXkNWsvhGdPbOySnDtqh+yhhohSWn8C7LD6MvcnynqAf5+tSlbWrphAl Zopkj/EZ7TwionXAwV53V3fb6GKxTT5RIatvz16OW2veMPgnIyrH+WCcp7JoXVCr /fHx0ODVAyidGuql/pQtPfNGDoTCT5jFIiJ3t+Q6MqP2SvBNkY7miUybC1tiC82c I8Sw2330O/4Tb2kZCGtz9bAKqxNXoz3Ph8R4d8XbRsZB9k3XXvkG1y+pnHhcwJ4j 5ykFl6oHDp+0xwKMdS6Y9MRHn46FEf0q1gtHg4dw9FpOQ9MQGqa6Fz8KKUB5POg= =BtaY -----END PGP SIGNATURE----- ------------------------------------------------------------------------------ Want excitement? Manually upgrade your production database. When you want reliability, choose Perforce Perforce version control. Predictably reliable. http://pubads.g.doubleclick.net/gampad/clk?id=157508191&iu=/4140/ostg.clktrk _______________________________________________ bitcoin-list mailing list bitcoin-list@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/bitcoin-list
