Unlock remote account

Question

I have smart contract deployed that accepts funds (via fallback function function() payable { ... }). Also I have frontend using web3 to send funds.

When I tested it with local node (and JSON wallets presented locally) evrything works fine - web3.personal.unlockAccount(account, password) unlocked account with data provided by user then funds sent to contract.

Now I deployed geth node on standalone VPS and connecting to it using code:

var Web3 = require('web3');
this.web3 = new Web3();
this.web3.setProvider(new Web3.providers.HttpProvider('http://my-node-addr.net:18545/'));

if(this.web3.isConnected()) {
  console.log('web3 connected');
} else {
  console.log('web3 NOT connected');
}

It shows that client connected successfully. But when I am trying to send funds code failed on line

web3.personal.unlockAccount(account, password);

with error Error: no key for given address or file. Of course, my node cannot contain all client's wallet file (nobody want to upload it).

Here is how I am sending transaction:

this.contract.sendTransaction({ from: account, value: amount, gas: 400000 })
.then(() => {
    // OK, everything fine!
})
.catch(error => {
    // I am here
    console.log('Oops...', 'Error happened during your payment: ' + error, 'error');
});

UPD: What I want: provide html page with fields "account", "password" and "amount" that allows users to send ethers to predefined address. Of course my node will not have UTC-..... files (wallets).

Answer 1

The method sendTransaction works because geth has access to the private key. In your scenario since the private key is in the client geth has no access to it and will not be able to sign the transaction.

You need to sign the transaction in the client side and use sendRawTransaction to broadcast your signed transaction. You can use eth-lightwallet to manage keys client side, if you want something more low level you can use ethereumjs-tx to create and sign your own transactions.