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Send private transactions

This tutorial shows you how to send private transactions.

Prerequisites​

Steps​

1. Create private contract​

In the Node-0 directory, copy and paste the following to a file called private-contract.js. On the highlighted line, replace the placeholder for privateFor with the base64 content of the tessera1.pub key file. For example, 1oRj9qpgnNhr/ZUggeMXnXsWMuVgedS6gfimpEVt+EQ=.

caution

Don't include the sender's node in privateFor. To create a private contract visible to the sender's node only, use this format: privateFor: [].

Smart contract example
a = eth.accounts[0];
web3.eth.defaultAccount = a;

// abi and bytecode generated from simplestorage.sol:
// > solcjs --bin --abi simplestorage.sol
var abi = [
  {
    constant: true,
    inputs: [],
    name: "storedData",
    outputs: [{ name: "", type: "uint256" }],
    payable: false,
    type: "function",
  },
  {
    constant: false,
    inputs: [{ name: "x", type: "uint256" }],
    name: "set",
    outputs: [],
    payable: false,
    type: "function",
  },
  {
    constant: true,
    inputs: [],
    name: "get",
    outputs: [{ name: "retVal", type: "uint256" }],
    payable: false,
    type: "function",
  },
  {
    inputs: [{ name: "initVal", type: "uint256" }],
    payable: false,
    type: "constructor",
  },
];

var bytecode =
  "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";

var simpleContract = web3.eth.contract(abi);
var simple = simpleContract.new(
  42,
  {
    from: web3.eth.accounts[0],
    data: bytecode,
    gas: 0x47b760,
    privateFor: ["<Tessera 1 public key>"],
  },
  function (e, contract) {
    if (e) {
      console.log("err creating contract", e);
    } else {
      if (!contract.address) {
        console.log(
          "Contract transaction send: TransactionHash: " +
            contract.transactionHash +
            " waiting to be mined...",
        );
      } else {
        console.log("Contract mined! Address: " + contract.address);
        console.log(contract);
      }
    }
  },
);

2. Create account​

In the Node-0 directory, create an account.

geth --datadir data account new

3. Unlock account​

Accounts are locked by default and must be unlocked before sending the transaction. Use the geth console to display and unlock the account.

geth attach geth.ipc

Display the accounts.

eth.accounts;

Unlock the account using the account key displayed by eth.accounts.

javascript personal.unlockAccount("<account key>")

Type in the account password when prompted.

info

By default, accounts remain unlocked for 5 minutes. After 5 minutes, the account is relocked.

4. Send private transaction​

caution

All participants listed in privateFor must have their private transaction managers running when the private transaction is sent. Otherwise, the transaction doesn't propagate and an error is returned.

In the geth console, run loadScript to deploy the contract and send a private transaction from node 0 to node 1.

loadScript("private-contract.js");

The GoQuorum logs for node 0 indicate the private transaction was sent.

DEBUG[12-08|13:53:09.380] sending private tx txnType=3 data=606060…00002a privatefrom= privatefor="[yrrHrbeaXzZCYJ4DPXrunvms1/jy5zDvoH5KnNyW4VE=]" privacyFlag=0
DEBUG[12-08|13:53:09.381] Simulated Execution EVM call finished runtime=594ns
TRACE[12-08|13:53:09.381] after simulation affectedCATxHashes=map[] merkleRoot=000000…000000 privacyFlag=0 error=nil
INFO [12-08|13:53:09.629] sent private signed tx data=606060…00002a hash=f93744…407111 privatefrom= privatefor="[yrrHrbeaXzZCYJ4DPXrunvms1/jy5zDvoH5KnNyW4VE=]" affectedCATxHashes=map[] merkleroot=000000…000000 privacyflag=0
DEBUG[12-08|13:53:09.629] Handle Private Transaction finished took=249.112348ms
INFO [12-08|13:53:09.630] Private transaction signing with QuorumPrivateTxSigner

The Tessera logs indicate the transaction payload was distributed and received.