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vk = ecdsa.VerifyingKey.from_string(bytes.fromhex(pubKey),curve=ecdsa.SECP256k1)

if vk.verify(bytes.fromhex(signature), bytes.fromhex(sha256_hash), hashlib.sha256, sigdecode=sigdecode_der) == True: # True
        print("Signature is Valid")
else:
        print("Signature is not Valid")

I am trying to verify a transaction using secp256k1_generator, but I can't seem to get the signature into the correct (r,s) format, and am getting the following output

 File "/.local/lib/python3.10/site-packages/ecdsa/keys.py", line 741, in verify_digest
    raise BadSignatureError("Signature verification failed")
ecdsa.keys.BadSignatureError: Signature verification failed

I have taken help of Signature verification in python using compressed public key and

https://stackoverflow.com/questions/73630540/how-to-verify-ecdsa-signatures-with-python But still I am getting this error. How can I resolve it?

1 Answer 1

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Are you sure that the r and s that you have generated are correct? If yes converting this (r,s) to DER can be done in this way.

def der(self):
        rbin = self.r.to_bytes(32, byteorder='big')
        # remove all null bytes at the beginning
        rbin = rbin.lstrip(b'\x00')
        # if rbin has a high bit, add a \x00
        if rbin[0] & 0x80:
            rbin = b'\x00' + rbin
        result = bytes([2, len(rbin)]) + rbin  # <1>
        sbin = self.s.to_bytes(32, byteorder='big')
        # remove all null bytes at the beginning
        sbin = sbin.lstrip(b'\x00')
        # if sbin has a high bit, add a \x00
        if sbin[0] & 0x80:
            sbin = b'\x00' + sbin
        result += bytes([2, len(sbin)]) + sbin
        return bytes([0x30, len(result)]) + result

here self.r and self.s are integers previously generated

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