Bitcoin QT user gets an address that already exists!
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@alikim from Bitcointalk put up this post: [url=https://bitcointalk.org/index.php?topic=314617.0]I generated an address that already exists[/url]
In his words:
[quote]That shouldn’t be very probable, should it?I used Bitcoin Qt client, pressed “New address” button to generate the address, sent a small amount to it and then checked on blockchain.info if the transaction was registered. To my surprise there are two other transactions made over a year ago using that address.
https://blockchain.info/address/1J9UHx3q9D1ZxZ5KwV8VGWJd7ksyTJtLTB[/quote]
If this is true is this a problem for all QT clients?
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Its random chance. Very small chance but a finite one nonetheless.
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Wow. This is going to be one to watch. Chances are if he did generate a private key to an address already in use then there is a flaw in the RNG. We will watch to see the result and possible fix.
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This is kind of cool actually, if it happened on a minute statistically probable level.
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As with all probabilities there is a chance of it happening. However the address space is amazingly massive, the odds of this happening are a staggering.
2^160
or
1,461,501,637,330,902,918,203,684,832,716,283,019,655,932,542,976 to 1 :o -
[quote name=“UKMark” post=“31925” timestamp=“1382276030”]
As with all probabilities there is a chance of it happening. However the address space is amazingly massive, the odds of this happening are a staggering.
2^160
or
1,461,501,637,330,902,918,203,684,832,716,283,019,655,932,542,976 to 1 :o
[/quote]He should play the lottery.
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[quote name=“erk” post=“31912” timestamp=“1382271375”]
That’s the way it’s designed, there is no checking to see if an address is unique. It’s supposed to be improbable.
[/quote]i guess the Client could look at TX history when generating bitcoin address, but it shouldn’t have to, its really is 999,000,000,000,000,000,000 in 1 chance of getting a collision
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I guess technically both of them as its the same logical account. First to move the coins wins I suppose. That’s a scarry thought.
Is there anything stopping me just creating millions of new accounts looking to duplicate accounts? Its almost mining in itself?
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Although with that huge number millions isn’t going to cut it.
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There’s no proof of this. The most likely candidate is that user error is involved.
Nothing to see here.
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Come on guys, no panic :) It’s his address. He used it previously for a 50 BTC change when sent 50 BTC using a 100 BTC input. He had this change spent later, and there is a record of this transaction in his wallet. So, his client has re-used an old address.
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so this number is somewhere in the region of a Thousand quinquavigintillion or Quinquagintillion if you happen to be american (who happily renamed all the large numbers).
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[quote name=“Kevlar” post=“32006” timestamp=“1382306044”]
There’s no proof of this. The most likely candidate is that user error is involved.Nothing to see here.
[/quote]This is what happened. Someone already had him go through diagnostics and found that the address he “generated” was actually one he had before. He had restored a backup which stores 100 addresses in the beginning. This “new” address was just because he backed up his wallet, restored it and it was running through the spool of 100 and that was the next address in the line.
In other words, it was user error. The same thing has been reported over and over by different people and so far every time it’s been from people restoring from backups and not understanding how the addresses are stored.
