ethereum signatures are invalid

[picard276]

I am trying to figure out how to get this yubihsm2 to work with signing eth transactions. I have been using the python lib and so far i have had some basic setup. Below is an abbreviation of what i have

web3_endpoint = ''

web3 = Web3(HTTPProvider(web3_endpoint))

hsm = YubiHsm.connect("http://localhost:12345")
session = hsm.create_session_derived(1, "password")
key = session.get_object(1,OBJECT.ASYMMETRIC_KEY)

'''key = AsymmetricKey.generate(session, 1, "EC Key", 1, CAPABILITY.SIGN_ECDSA, ALGORITHM.EC_K256)'''
pub_key = key.get_public_key()'

raw_pub = pub_key.public_bytes(
encoding=serialization.Encoding.X962,
format=serialization.PublicFormat.UncompressedPoint
)
print ("Public key (Uncompressed):\n",binascii.b2a_hex(raw_pub))
unindexPub = raw_pub[1:]
public_key_hash = Web3.keccak(unindexPub)
address_bytes = public_key_hash[-20:]
address = address_bytes.hex()
print(address)

Now so far i can consistently get the same public key and it looks correct. I then get the same public key each time. When i say correct, the formatting looks correct and is the correct number of bytes.

1). should i be using the commented out public key formatting or the uncompressed X962 encoding that i have above.

From there, this is where things get a bit weird
transaction = {
'to': Web3.toChecksumAddress('0x785AB1daE1b0Ee3f2412aCF55e4153A9517b07e1'),
'gas': 21000,
'gasPrice': Web3.toWei(5, 'gwei'),
'value': 1,
'nonce': 1,
'chainId': 4,
}
serializable_transaction = serializable_unsigned_transaction_from_dict(transaction)
transaction_hash = serializable_transaction.hash()
print(transaction_hash.hex())

signature = key.sign_ecdsa(transaction_hash,hashes.SHA3_256())
r, s = ecdsa.util.sigdecode_der(signature, ecdsa.SECP256k1.generator.order())
print("r: "+str(r)+"\ns: "+str(s))

v = 28

encoded_transaction = encode_transaction(serializable_transaction, vrs=(v, r, s))
web3.eth.sendRawTransaction(encoded_transaction)

I am settings v to 28.. i also test it with 27.. I could use the correct amount with the chainid.. but it's not necessary right from the perspective of trying to get a valid signature (recoverable to get the same public key each time). Sometimes i am getting the error "invalid sender" and other times i am getting the error "insufficient gas." If i take the signature output and use a javascript lib to try to find the public key, each time i am getting a different public key. But i keep consistently generating the same public key from the yubihsm2 in this python app.

I have also commented out in sign_ecdsa the hashing function as i am passing in the data already hashed (in order to use keccak256).

Is there something i am missing? Why are these transactions not signing correctly for eth?