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Title: Blockchain Hash is it possible to repeat it again on other Block? Post by: macdevil007 on May 03, 2018, 07:43:18 AM A newbie question...
Example: Block 12345 got hash Hash 0000000000000000001ac4321c39d3da75489e6951137c64d1ffa42ccae885cd is it possible to happen this Hash again on Block 67890? thanks for those who will answer.. Title: Re: Blockchain Hash is it possible to repeat it again on other Block? Post by: bitperson on May 03, 2018, 07:50:08 AM Example: Block 12345 got hash Hash 0000000000000000001ac4321c39d3da75489e6951137c64d1ffa42ccae885cd It is very unlikely, as it is the block header, which is different for each block, that is being hashed. Please see https://en.bitcoin.it/wiki/Block_hashing_algorithm for the contents of the block header.is it possible to happen this Hash again on Block 67890? Title: Re: Blockchain Hash is it possible to repeat it again on other Block? Post by: mocacinno on May 03, 2018, 07:54:18 AM If i remember correctly, this is one of the checks a node does before accepting a block... If the hash of a new block is the same as the hash of a previous block, the new block will be rejected...
Source: my memory... Might not be 100% accurate ;) EDIT: do realise the odds of a collision are incredibly small Title: Re: Blockchain Hash is it possible to repeat it again on other Block? Post by: JohnGalt on May 03, 2018, 08:27:03 AM If i remember correctly, this is one of the checks a node does before accepting a block... If the hash of a new block is the same as the hash of a previous block, the new block will be rejected... Source: my memory... Might not be 100% accurate ;) EDIT: do realise the odds of a collision are incredibly small While the odds of a collision are extremely low, they rise with an increasing difficulty. And since the number of blocks is unbounded, the probability of a collision occurring at some pojnt in the future is 100%. Title: Re: Blockchain Hash is it possible to repeat it again on other Block? Post by: mocacinno on May 03, 2018, 08:30:02 AM While the odds of a collision are extremely low, they rise with an increasing difficulty. And since the number of blocks is unbounded, the probability of a collision occurring approaches 100%. Sure, given an infinite timeframe, the odds become 100%, but still, the block would get rejected, so it's just the miner who mined the block with the colliding hash loses the block reward + fees for that block, and that's about all that'll happen. In our lifetime, i doubt we'll ever see such a collision happening... My math is not good enough to calculate the exact odds tough, but it would be an extremely small number... Title: Re: Blockchain Hash is it possible to repeat it again on other Block? Post by: macdevil007 on May 06, 2018, 12:38:23 PM Thanks and appreciate your responses.. Got an idea already about Hash in Blockchain
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