[Ethereum] How to sign transaction for calling sendRawTransaction JSON RPC method

To expand the other response, to provide offline transaction signing in Nethereum you can do the following:

First, you will need your private key, and sender address. You can retrieve the sender address from your private key using Nethereum.Core.Signing.Crypto.EthECKey.GetPublicAddress(privateKey); if you only have the private key.

var privateKey = "0xb5b1870957d373ef0eeffecc6e4812c0fd08f554b37b233526acc331bf1544f7"; var senderAddress = "0x12890d2cce102216644c59daE5baed380d84830c";

Now using web3 first you will need to retrieve the total number of transactions of your sender address.

var web3 = new Web3(); var txCount = await web3.Eth.Transactions.GetTransactionCount.SendRequestAsync(senderAddress);

The txCount will be used as the nonce to sign the transaction.

Now using web3 again, you can build an encoded transaction as following:

var encoded = web3.OfflineTransactionSigning.SignTransaction(privateKey, receiveAddress, 10, txCount.Value);

If you need to include the data and gas there are overloads for it.

You can verify an encoded transaction: Assert.True(web3.OfflineTransactionSigning.VerifyTransaction(encoded));

Or get the sender address from an encoded transaction:

web3.OfflineTransactionSigning.GetSenderAddress(encoded);

To send the encoded transaction you will "SendRawTransaction"

var txId = await web3.Eth.Transactions.SendRawTransaction.SendRequestAsync("0x" + encoded);

You can see this example on the unit test

Or a "real" implementation on the Game sample

eth_sendTransaction can be used for sending Ether, for creating contracts and calling contract function. It all depends on the parameters.

1. For just sending Ether, you'd want to fill the value, to and from fields.

2. For creating contracts, you'd leave the to empty but fill in data.

3. For calling a contract function, you'd fill in both to and data, and optionally value if you also want to transfer Ether to the contract.