# Need some help confirming transactions using sha256

Discussion in 'Python' started by kryptox.exchange@gmail.com, Jan 31, 2013.

1. ### Guest

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 ofeach day thus allowing you to prove they didn't cheat. So they provide thefollowing to allow you to verify the calculation of the dice roll:

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
>>> import hashlib, hmac
>>> secret = '10812806653842663997bf5971637f86f26c71a4716276d7fa8f323a83588d91:1'
>>> for nout in range(10): print nout, int(hmac.new(secret, "%s:%d" % (txid, nout), hashlib.sha256).hexdigest()[:4], 16)

....
0 39800
1 4705
2 24058
3 11188
4 36307
5 781
6 62165
7 44612
8 17042
9 46099
>>>

idx 1 should equal 18660 but it doesn't. What am I doing wrong?

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 getthe "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 foridx 1 only.

ie.
"txid here", "lucky number for idx 1"

Thanks for any help in advance!

Edit/Delete Message

, Jan 31, 2013

2. ### Guest

Ok, I'm still stuck!

I do however now think that I'm not supposed to use hmac here.

, Jan 31, 2013

3. ### Peter PearsonGuest

On Thu, 31 Jan 2013 08:43:03 -0800 (PST), 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 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
>>>> import hashlib, hmac
>>>> secret = '10812806653842663997bf5971637f86f26c71a4716276d7fa8f323a83588d91:1'

[snip]

>>> secret = '10812806653842663997bf5971637f86f26c71a4716276d7fa8f323a83588d91:1'
>>> hashlib.sha256(txid+":"+secret).hexdigest()

'dfa8769be81a543002865c88a5b52fa07f3b67fc7cd9b519c3f6a6452bcd48e4'
>>> 0x48e4

18660
>>>

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

--
To email me, substitute nowhere->spamcop, invalid->net.

Peter Pearson, Jan 31, 2013
4. ### Guest

On Thursday, January 31, 2013 6:55:05 PM UTC+1, Peter Pearson wrote:
> On Thu, 31 Jan 2013 08:43:03 -0800 (PST), 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

>

>
> >>>> import hashlib, hmac

>

>
> >>>> secret = '10812806653842663997bf5971637f86f26c71a4716276d7fa8f323a83588d91:1'

>
> [snip]
>
>
>

>
> >>> secret = '10812806653842663997bf5971637f86f26c71a4716276d7fa8f323a83588d91:1'

>
> >>> hashlib.sha256(txid+":"+secret).hexdigest()

>
> 'dfa8769be81a543002865c88a5b52fa07f3b67fc7cd9b519c3f6a6452bcd48e4'
>
> >>> 0x48e4

>
> 18660
>
> >>>

>
>
>
> . . . which is the number you wanted, right?
>
>
>
>
>
> --
>
> To email me, substitute nowhere->spamcop, invalid->net.

Yes, thank you Peter!

, Jan 31, 2013