Ups, I forgot that you take the midstate which of course depends on the version number. So forget everything I said about the version bits. You are right. But why take the midstate? It can be any hash of the first chunk. So you probably want to take a hash function that's available in standard software libraries. And I suppose midstate() is not.
On Wed, May 11, 2016 at 11:28 AM, Timo Hanke <timo.ha...@web.de> wrote: > Sorry, you must have meant all 12 bytes. That makes finding a collision > substantially harder. However, you may have to restrict yourself to 10 > bytes because you don't know if any hardware does timestamp rolling > on-chip. Also you create an incentive to mess around with the version bits > instead, so you would have to fix that as well. So it basically means a new > mining header with the real blockheader as a child header. > > On Wed, May 11, 2016 at 9:24 AM, Timo Hanke <timo.ha...@web.de> wrote: > >> Luke, do you mean to replace the first 4 bytes of the second chunk (bytes >> 64..67 in 0-based counting) by the XOR of those 4 bytes with the first 4 >> bytes of the midstate? (I assume you don't care about 12 bytes but rather >> those 4 bytes.) >> >> This does not work. All it does is adding another computational step >> before you can check for a collision in those 4 bytes. It makes finding a >> collision only marginally harder. >> >> On Wed, May 11, 2016 at 7:28 AM, Luke Dashjr via bitcoin-dev < >> bitcoin-dev@lists.linuxfoundation.org> wrote: >> >>> On Wednesday, May 11, 2016 12:20:55 PM Sergio Demian Lerner via >>> bitcoin-dev >>> wrote: >>> > On Tue, May 10, 2016 at 6:43 PM, Sergio Demian Lerner < >>> > sergio.d.ler...@gmail.com> wrote: >>> > > You can find it here: >>> > > >>> https://bitslog.wordpress.com/2014/03/18/the-re-design-of-the-bitcoin-blo >>> > > ck-header/ >>> > > >>> > > Basically, the idea is to put in the first 64 bytes a 4 byte hash of >>> the >>> > > second 64-byte chunk. That design also allows increased nonce space >>> in >>> > > the first 64 bytes. >>> > >>> > My mistake here. I didn't recalled correctly my own idea. The idea is >>> to >>> > include in the second 64-byte chunk a 4-byte hash of the first chunk, >>> not >>> > the opposite. >>> >>> What if we XOR bytes 64..76 with the first 12 bytes of the SHA2 midstate? >>> Would that work? >>> >>> Luke >>> _______________________________________________ >>> bitcoin-dev mailing list >>> bitcoin-dev@lists.linuxfoundation.org >>> https://lists.linuxfoundation.org/mailman/listinfo/bitcoin-dev >>> >> >> >
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