Need some help confirming transactions using sha256

Peter Pearson ppearson at nowhere.invalid
Thu Jan 31 18:55:05 CET 2013


On Thu, 31 Jan 2013 08:43:03 -0800 (PST), kryptox.exchange at gmail.com wrote:

> I'm wondering if anyone can help me as I can't seem to get
> this to work. There is an online dice game that is
> provably fair by calculating the 'dice roll' using using a
> sha256 hash calculated against my transaction ID generated
> by me. The secret used to make the calculation is revealed
> at the end of each day thus allowing you to prove they
> didn't cheat. So they provide the following to allow you
> to verify the calculation of the dice roll:
>
> Secret used = r7A7clvs9waizF+6QEiI0tgAq1ar48JItK3kg9kaeAFXz2vsMsHmOd9r9fhkmtxTz3CQnGAPMaDeKLvgb1A2VA
> Secret hash sha256(r7A7clvs9waizF+6QEiI0tgAq1ar48JItK3kg9kaeAFXz2vsMsHmOd9r9fhkmtxTz3CQnGAPMaDeKLvgb1A2VA) = 48d78d573b9b8e11a13a72d9a78011f2e5d9754d89de47b209f32c51777f535d
> Lucky hash sha256(r7A7clvs9waizF+6QEiI0tgAq1ar48JItK3kg9kaeAFXz2vsMsHmOd9r9fhkmtxTz3CQnGAPMaDeKLvgb1A2VA:108128 06653842663997bf5971637f86f26c71a4716276d7fa8f323a83588d91:1) = dfa8769be81a543002865c88a5b52fa07f3b67fc7cd9b519c3f6a6452bcd48e4
>
> Lucky Number 0x48e4 = 18660
>
> So, I'm doing the following:
>
> C:\Python27>python
> Python 2.7.3 (default, Apr 10 2012, 23:24:47) [MSC v.1500 64 bit (AMD64)] on win32
> Type "help", "copyright", "credits" or "license" for more information.
>>>> import hashlib, hmac
>>>> txid = 'r7A7clvs9waizF+6QEiI0tgAq1ar48JItK3kg9kaeAFXz2vsMsHmOd9r9fhkmtxTz3CQnGAPMaDeKLvgb1A2VA'
>>>> secret = '10812806653842663997bf5971637f86f26c71a4716276d7fa8f323a83588d91:1'
[snip]

>>> txid = 'r7A7clvs9waizF+6QEiI0tgAq1ar48JItK3kg9kaeAFXz2vsMsHmOd9r9fhkmtxTz3CQnGAPMaDeKLvgb1A2VA'
>>> secret = '10812806653842663997bf5971637f86f26c71a4716276d7fa8f323a83588d91:1'
>>> hashlib.sha256(txid+":"+secret).hexdigest()
'dfa8769be81a543002865c88a5b52fa07f3b67fc7cd9b519c3f6a6452bcd48e4'
>>> 0x48e4
18660
>>> 

. . . which is the number you wanted, right?


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