Different Values for v, r, s? What am I doing wrong?

Question

lets assume I have this private key (test account on ropsten, no need to worry):

785cdcd731a1b2438ec4511a25d04efbdc499ed350df612364af1aa6f4fd6abd

When I use Pyethereum to run

v, r, s = ecsign(tx['hash'], normalize_key(private_key))

then v, r, s = (28, 70432465444433342622726730664370509023990924819271715983647847605365849029795, 7960080711554037742197166599216482712965266632510536462814358773930726674178)

When I compare this with the actual transaction:

{'blockHash': HexBytes('0x47b8f62c1400dae65105d2f8e03824bfc58481c0b32f45788ad3378fbc05e9f6'), 
'blockNumber': 4156209, 
'from': '0x4e5C95B38bd0B18B83f130a1ffae58cFC58961DE', 
'gas': 21000, 
'gasPrice': 8000000000, 
'hash': HexBytes('0x8ec420a3ba331f2a967ecdaf69b78bbb604ebbb2554a8c635142b7b306defaae'), 
'input': '0x', 
'nonce': 0, 
'r': HexBytes('0xe298a05754cc5a24790bb8c21ecb60fd93f2d096146af7397440697a338dff46'), 
's': HexBytes('0x5999f680f17e505c979c43a3a9e7707c817efde705f967681d8a5066b49e5352'), 
'to': '0xED6CA7d908f897d0B0D5f9B9E7Aa470698E10b1b', 
'transactionIndex': 27, 
'v': 42, 
'value': 1000000000000000000}

The Values for r,s,v are very different. (Event when I convert them with bytes.from_hex(tx['r']))

Q1: Dose anyone know what I am doing Wrong?

Just to make sure: The transaction was made with metamask and then the key was exported from metamask, so there is no chance that the key to sign the transaction was different.

Q2: Is there a better way to do this?

Thanks in advance :)

Answer 1

The values that you present for the result of the signature are not correct. I did this using the same transaction you show and the privatekey provided by you. When you sign the transaction using the private key that you show, you get:

'r': 102492371167525662808729438177964772018202086674566648709527465604425496526662,

's': 40527872430728510063557974166309434109284218396283342950340797635881485620050,

'v': 42

the representation of r and s in hexadecimal are s = '0x5999f680f17e505c979c43a3a9e7707c817efde705f967681d8a5066b49e5352' r = '0xe298a05754cc5a24790bb8c21ecb60fd93f2d096146af7397440697a338dff46'

that are the values that you show for the actual transaction.

EDIT

privatekey = '0x785cdcd731a1b2438ec4511a25d04efbdc499ed350df612364af1aa6f4fd6abd'
transaction = {
     'to': '0xED6CA7d908f897d0B0D5f9B9E7Aa470698E10b1b',
     'value': 1000000000000000000,
     'gas': 21000,
     'gasPrice': 8000000000,
     'nonce': 0,
     'data':'0x',
     'chainId': 3}

signed = w3.eth.account.signTransaction(transaction,privatekey)

Note that as @Ismael points out, the issue in your code is that the hash that you are using is not the correct one.

Hope this helps.

Answer 2

Before EIP155 to sign you hash the RLP encoding of the transaction without r, s, v. See https://github.com/ethereum/pyethereum/blob/develop/ethereum/transactions.py#L133.

The default of tx["hash"] is to include r, s and v in the hash. And your transaction will not validate.

After EIP155 the procedure indicates you have to replace r, s and v for some specific values (the chain_id and zeros).