January 31st, 2013, 11:12 AM
Need some help confirming transactions using sha256
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:
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'
>>> for nout in range(10): print nout, int(hmac.new(secret, "%s:%d" % (txid, nout), hashlib.sha256).hexdigest()[:4], 16)
idx 1 should equal 18660 but it doesn't. What am I doing wrong?
EDIT: Slowly trying to figure this out. I believe that using hmac is part of the mistake.
Secondly, I'm wondering if someone could help take it one step further. I would like to import a .txt file with a unique transaction ID on each line. So txid = transactions.txt or something like this. I would like it to get the "lucky number" based on a static sha256 which I would supply and the script would output the result to a text file. I'd like the output to be for idx 1 only.
"txid here", "lucky number for idx 1"
Thanks for any help in advance!