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http://www.cryptocoinsnews.com/2014/01/09/warning-ghash-io-nearing-51-leave-pool/ http://www.cryptocoinsnews.com/2014/01/09/warning-ghash-io-n... ---The attack

by smtddr 13y ago

http://www.cryptocoinsnews.com/2014/01/09/warning-ghash-io-nearing-51-leave-pool/ http://www.cryptocoinsnews.com/2014/01/09/warning-ghash-io-n... ---The attacker can----: Reverse transactions that he sends while he’s in control Prevent some or all transactions from gaining any confirmations Prevent some or all other generators from getting any generations Double spend Bitcoins ---The attacker cannot---: Reverse other people’s transactions Prevent transactions from being sent at all (they’ll show as 0/unconfirmed) Change the number of coins generated per block Create coins out of thin air Send coins that never belonged to him

drcongo 13y ago
Thanks.
michaelmior 13y ago
Is there really a practical difference between double spending and generating coins out of thin air? I can just duplicate coins by sending to two wallets I control. Or is there something that would prevent me from later spending some of those coins?
- lostsock 13y ago
  You can spend the same coins twice, but you do not end up with 2x as many if you don't spend them at all. So you can end up with 1x worth of goods and 1x in your wallet like you never spent them but you can't end up with 2x in your wallet.
- tyilo 13y ago
  Given 1 BTC sent to two different addresses, there is maximum only one of them that is valid at one point in time. However after some time, the other coin could be valid and the first coin could be invalid. The timing attack gets harder the longer time has gone since the coin was sent.
- nano_o 13y ago
  I think that they would not be able to do that: only one of the two transactions could be in the longest correct block-chain. That's because it is easy for the clients to detect and reject a block-chain that contains double spending. What they can do is pay for goods or services and revert the transaction after the goods or services have been delivered.

by smtddr 13y ago

drcongo 13y ago

Thanks.

michaelmior 13y ago

Is there really a practical difference between double spending and generating coins out of thin air? I can just duplicate coins by sending to two wallets I control. Or is there something that would prevent me from later spending some of those coins?

lostsock 13y ago
You can spend the same coins twice, but you do not end up with 2x as many if you don't spend them at all. So you can end up with 1x worth of goods and 1x in your wallet like you never spent them but you can't end up with 2x in your wallet.
tyilo 13y ago
Given 1 BTC sent to two different addresses, there is maximum only one of them that is valid at one point in time. However after some time, the other coin could be valid and the first coin could be invalid. The timing attack gets harder the longer time has gone since the coin was sent.
nano_o 13y ago
I think that they would not be able to do that: only one of the two transactions could be in the longest correct block-chain. That's because it is easy for the clients to detect and reject a block-chain that contains double spending. What they can do is pay for goods or services and revert the transaction after the goods or services have been delivered.