Help in Programming bitcoin python module

[unknowncustomer]

Hello,

I would need some help on Python:

I am trying to import helper package on Python with module hash256 like the colored lined of the below code however it’s not working.

from ecc import S256Point, G, N
from helper import hash256
e = int.from_bytes(hash256(b'my secret'), 'big')
z = int.from_bytes(hash256(b'my message'), 'big')
k = 1234567890
r = (k*G).x.num
k_inv = pow(k, N-2, N)
s=(z+r*e)*k_inv%N
point = e*G

print(point) # S256Point(028d003eab2e428d11983f3e97c3fa0addf3b42740df0d211795ffb3be2f6c52, \ 0ae987b9ec6ea159c78cb2a937ed89096fb218d9e7594f02b547526d8cd309e2)
print(hex(z)) # 0x231c6f3d980a6b0fb7152f85cee7eb52bf92433d9919b9c5218cb08e79cce78
print(hex(r)) # 0x2b698a0f0a4041b77e63488ad48c23e8e8838dd1fb7520408b121697b782ef22
print(hex(s)) # 0xbb14e602ef9e3f872e25fad328466b34e6734b7a0fcd58b1eb635447ffae8cb9
Or do you have an idea to do a double sha256 (it is hash256)?

I tried this:

from hashlib import sha256 as h

print(h(h("my secret".encode()).hexdigest().encode()).hexdigest())
It's almost working however the result does not match as it is not starting with 0x.

[PowerGlove]

Howdy!

Yup, it looks to me like that hash256 function would've done a double SHA-256. You can define your own function to replace that import, like this:

Code:

from hashlib import sha256

def hash256(data):

    return sha256(sha256(data).digest()).digest()

That should work identically to the missing function (i.e. print(hex(int.from_bytes(hash256(b'my message'), 'big'))) should emit 0x231c6f3d980a6b0fb7152f85cee7eb52bf92433d9919b9c5218cb08e79cce78).

[unknowncustomer]

OMG it is working thanks a lot !!
I am quite new to Python and Programming Bitcoin, any idea where I should start ? which books ?
Thanks !!

[witcher_sense]

print(h(h("my secret".encode()).hexdigest().encode()).hexdigest())
It's almost working however the result does not match as it is not starting with 0x.

Your solution produces a completely different hash because before making a second hash, you represent bytes as hex values instead of raw bytes. Only use hexdigest() method after you have calculated a final hash.

Instead of

Code:

print(h(h("my secret".encode()).hexdigest().encode()).hexdigest())

Do

Code:

print(h(h("my secret".encode()).digest()).hexdigest())

You can also use f-strings to add 0x to final representation:

Code:

print(f'0x{h(h("my secret".encode()).digest()).hexdigest()}')

[PowerGlove]

OMG it is working thanks a lot !!

I'm glad I could help!

I am quite new to Python and Programming Bitcoin, any idea where I should start ? which books ?

I'd say you're already on the right path; just keep trying to do stuff and ask questions when you get really stuck. The best programmers I know basically taught themselves by trial-and-error. Books, and courses, etc. can help, but (in my experience) nothing will teach you better or faster than mindful practice.

In the beginning, you'll feel like this guy:



But after a while, you'll start to feel like this guy:



Just keep practicing. (Feel free to send me a PM if you get really stuck on something.)

[ABCbits]

OMG it is working thanks a lot !!
I am quite new to Python and Programming Bitcoin, any idea where I should start ? which books ?
Thanks !!

If you really insist to use book, people (including me) usually would recommend Mastering Bitcoin 2nd Edition[1]. Although if you prefer something shorter, check learn me a bitcoin website[2] instead. Aside from @PowerGlove said, i find reading documentation and example of certain library/function is helpful to prevent problem like this.

[1] https://github.com/bitcoinbook/bitcoinbook
[2] https://learnmeabitcoin.com/

[bettercrypto]

OMG it is working thanks a lot !!
I am quite new to Python and Programming Bitcoin, any idea where I should start ? which books ?
Thanks !!

Well, perhaps this might help you, friend, if you really want to, just check if this is what you are looking for
Good luck...

source:

- https://bitcoin.stackexchange.com/questions/5671/how-do-you-perform-double-sha-256-encoding
- https://gist.github.com/vincenzopalazzo/78c3545090ce609a145f4f6261a7fa0f
- https://stackoverflow.com/questions/72411835/how-to-correctly-do-a-double-sha256-hashing