2

I used data that comes from https://github.com/bitcoin/bips/blob/master/bip-0143.mediawiki#p2sh-p2wpkh. It is easy to know how to get sigHash. But when I try to recover public key, everything out off my expected.

And my question is

  1. The message to be signed was not 64f3b0f4dd2bb3aa1ce8566d220cc74dda9df97d8490cc81d89d735c92e59fb6?
  2. If the message is 64f3b0f4dd2bb3a...59fb6, is anything wrong to my code?

My code

import ecdsa

from ecdsa.ecdsa import int_to_string, string_to_int
from binascii import hexlify

prik = "eb696a065ef48a2192da5b28b694f87544b30fae8327c4510137a922f32c6dcf"
prik = bytes.fromhex(prik)

pubk = "03ad1d8e89212f0b92c74d23bb710c00662ad1470198ac48c43f7d6f93a2a26873"

sig = '3044022047ac8e878352d3ebbde1c94ce3a10d057c24175747116f8288e5d794d12d482f0220217f36a485cae903c713331d877c1f64677e3622ad4010726870540656fe9dcb'
sig = bytes.fromhex(sig)

raw_msg = "64f3b0f4dd2bb3aa1ce8566d220cc74dda9df97d8490cc81d89d735c92e59fb6"
raw_msg = bytes.fromhex(raw_msg)

try:
    pubkey = ecdsa.VerifyingKey.from_public_key_recovery(
        signature=sig, data=raw_msg, curve=ecdsa.curves.SECP256k1, sigdecode=ecdsa.util.sigdecode_der)
    print([hexlify(pub.to_string()) for pub in pubkey])

except Exception as e:
    raise e

def check_recovery(pub):

    padx = (b'\0'*32 + int_to_string(pub.pubkey.point.x()))[-32:]
    if pub.pubkey.point.y() & 1:
        ck = b'\3'+padx
    else:
        ck = b'\2'+padx

    return hexlify(ck)

lists = [check_recovery(p) for p in pubkey]
print(lists)
print([l == pubk for l in lists])

What I got was: [b'519e33c6b146628b4010ae2b56aa9127ae9b795c82df021979436296daf4cceac17eb495101c3c15011e9d5a08163122054ad375730ee2e219504540eb658211', b'd28ba1b718b542f52fe42b51635850b5900f111affbbdcbb63465e9a3dd79ffb80251268ba8d5b5ba4aaec8a682145af51b87bd7c7ab9e956895d31db24c4d4b'] [b'03519e33c6b146628b4010ae2b56aa9127ae9b795c82df021979436296daf4ccea', b'03d28ba1b718b542f52fe42b51635850b5900f111affbbdcbb63465e9a3dd79ffb'] [False, False]

What did I miss?

2

What i missed?

You are hashing sigHash (ie. the already hashed message) with SHA1 and then recover public key using that result which will give you 03519e33c6b146628b4010ae2b56aa9127ae9b795c82df021979436296daf4ccea as the recovered public key (can't re-calculate the second one with my c# code)! I believe that this is the source code of the from_public_key_recovery function you are using. You probably have to use another function like from_public_key_recovery_with_digest

  • thanks, you gave the right answer – kcorlidy Jul 29 at 12:22

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