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Author Topic: Why don't miners forge timstamps in order to decrease the difficulty?  (Read 559 times)
coinmachina
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July 15, 2017, 09:44:57 AM
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As far as I understand it the difficulty will be adjusted according to how long it took to generate a certain amount of blocks. The time the generation of these blocks took will be determined by the timestamps of the blocks.

My question now is: Why don't miners simply use wrong timestamps in order to exaggerate how long it took to generate the certain amount of blocks? So instead of putting the actual time into a block they simply take some date that is still in the future, e.g. one year from now. Then generating our certain amount of blocks did not take 2 weeks but more than one year.

As a consequence the difficulty would have to go down, wouldn't it?
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ranochigo
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July 15, 2017, 09:58:15 AM
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As far as I understand it the difficulty will be adjusted according to how long it took to generate a certain amount of blocks. The time the generation of these blocks took will be determined by the timestamps of the blocks.
Yes.
My question now is: Why don't miners simply use wrong timestamps in order to exaggerate how long it took to generate the certain amount of blocks? So instead of putting the actual time into a block they simply take some date that is still in the future, e.g. one year from now. Then generating our certain amount of blocks did not take 2 weeks but more than one year.

As a consequence the difficulty would have to go down, wouldn't it?
It is impossible for the blocks to deviate from the time by more than 2 hours. Nodes will reject any blocks that:
- Have a lower timestamp than the median of the previous 11 blocks
- Deviate from the network adjusted time (Average time given by the nodes connected) by 2 hours.

Any nodes that see your blocks will not see it as valid if they fit any of the two criteria above.

coinmachina
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July 15, 2017, 10:36:04 AM
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It is impossible for the blocks to deviate from the time by more than 2 hours. Nodes will reject any blocks that:
- Have a lower timestamp than the median of the previous 11 blocks
- Deviate from the network adjusted time (Average time given by the nodes connected) by 2 hours.

Okay thanks. But if the network time is the average time of connected nodes, couldn't a miner simply give a wrong time in order to push up the average?
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July 15, 2017, 11:08:48 AM
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It is impossible for the blocks to deviate from the time by more than 2 hours. Nodes will reject any blocks that:
- Have a lower timestamp than the median of the previous 11 blocks
- Deviate from the network adjusted time (Average time given by the nodes connected) by 2 hours.

Okay thanks. But if the network time is the average time of connected nodes, couldn't a miner simply give a wrong time in order to push up the average?
Each node sends the their timestamp at the time of connection and the nodes will store the timestamp. If it sees a block that doesn't fulfill their adjusted time, it is rejected. The miner cannot change the network adjusted time, only the nodes connected to each other can.

coinmachina
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July 15, 2017, 04:28:13 PM
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Why cannot a miner simply operate multiple nodes which send wrong timestamps to their peers and thus push the average time among all nodes further into the future?
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July 15, 2017, 04:38:42 PM
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Why cannot a miner simply operate multiple nodes which send wrong timestamps to their peers and thus push the average time among all nodes further into the future?
Of course they can. Its expensive plus nodes will not have their adjusted network time deviating from system time by more than 70 minutes.

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July 15, 2017, 06:21:10 PM
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nodes will not have their adjusted network time deviating from system time by more than 70 minutes.

Alright, I understand. Thanks
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