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I have a client running a private blockchain. It was started with the following command:

geth --datadir private-chain --mine --miner.threads 4 --http --http.addr 127.0.0.1 --http.port 8545 --http.api eth,net,web3,personal --networkid 3456 console 2> private-chain/private-chain.log

My transaction is created in the following function which is supposed to send one ether. It is part of a nodejs application I wrote to interact with the private blockchain. It uses the ethereumjs-tx package. The two account parameters are passed in as strings (which include the 0x). The accounts were created in the genesis block when I initialized the blockchain. The nonce is the number returned by web3.eth.getTransactionCount for the from_account.

function send_one_ether (from_account, nonce, private_key, to_account)
{
    var transaction_data =
    {
        "from": from_account,
        "to": to_account,
        "value": 1000000000000000000,
        "nonce": nonce
    };

    var transaction = new Transaction (transaction_data);

    var bytes = [];
    var private_key_bytes = private_key.substr (2); // remove the 0x
    for (var b = 0; b < private_key_bytes.length; b += 2)
    {
        var hex_byte = private_key_bytes.substr (b, 2);
        var int_byte = parseInt (hex_byte, 16);
        bytes.push (int_byte);
    }

    transaction.sign (Buffer.from (bytes));

    var verified = transaction.verifySignature (); // returns true
    var valid = transaction.validate (); // returns false

    var serialized_transaction = transaction.serialize ();
    web3.eth.sendSignedTransaction ("0x" + serialized_transaction.toString ("hex")).on ("receipt", console.log);
}

The private_key variable passed into the above function comes from the account's keystore file under the datadir, and it was decrypted using the following code.

var json_data = JSON.parse (fs.readFileSync (file_path));
const decrypted_account = web3.eth.accounts.decrypt (json_data, pw);

The transaction object's validate function returns false, and the error message I receive from web3.eth.sendSignedTransaction says invalid sender. Does anyone have any idea what could be wrong or how to get this to work?

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According to this issue, private blockchains are not supported by ethereumjs-tx. You have to use ethereumjs-common. So I think the problem was that, since my call to the Transaction constructor did not include a second parameter (an object specifying a chain), it probably defaulted to mainnet. But since the accounts I am working with are all on a private blockchain, they do not exist on the mainnet. Hence, the "invalid sender" error message.

In order to send the signed transaction to my private blockchain, I did the following.

const ethereumjs_common = require ('ethereumjs-common').default;

Then I had to change the way I was creating my Transaction object. (I think the first parameter to forCustomChain might simply be ignored in this case.)

var common = ethereumjs_common.forCustomChain ('ropsten', { networkId: 1994, chainId: 1994, name: 'geth' }, 'muirGlacier');
var transaction = new Transaction (transaction_data, { "common": common });

Finally, I had to add some gas to my transaction_data object.

var transaction_data =
{
    "from": from_account,
    "to": to_account,
    "value": 1000000000000000000,
    "gas": 60000,
    "nonce": nonce
};

After that, I got the receipt I was hoping to get.

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