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Author Topic: Block non-convergence soon?  (Read 1249 times)
mimarob
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December 26, 2010, 10:36:49 AM
 #1

hello!

am I rightly informed that the nonce is only 32 bits?

Does this in turn mean that there are "only" 2^32 or about 4 billion (4E9) combinations to try for each block?

If so, then when network hashing capacity reaches 4 000 000 kHash/sec the block would be solved in one second on average?

This contradicts the onlïne hash-rate calculator, which states about 4 hours, at present difficulty.

Sorry if this has been up before, but I'm really puzzled..

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davout
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December 26, 2010, 10:52:15 AM
 #2

The nonce overflows very often, but the timestamp changes often too Smiley, and even if it didn't the merkle root can

mimarob
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December 26, 2010, 11:10:08 AM
 #3

aha, so in general any given block with the nonce as the only variable is not likely to have a solution at all?

Are there some statistics on how often the non-nonce parts of the current block changes?
Mike Hearn
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December 26, 2010, 11:26:50 AM
 #4

There is an "extraNonce" part of the block. It's where the script would be in the generation transaction, called the coinbase data. When nonce overflows extraNonce is incremented.
jgarzik
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December 26, 2010, 03:37:12 PM
 #5

aha, so in general any given block with the nonce as the only variable is not likely to have a solution at all?

It is always possible that there is no solution for the entire range of nonce (0 - 0xffffffff).

However, the timestamp and extranonce are changed every few seconds, as is merkle tree root.  This helps avoid a situation where we get stuck with no solutions.

Jeff Garzik, bitcoin core dev team and BitPay engineer; opinions are my own, not my employer.
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