Audit

In this section, our focus is on implementing the logic to verify the node's submission value to K2. This verification process is commonly referred to as an audit.

Typically, a submission is made in each round, and the corresponding audit takes place in the subsequent round. Consequently, for a given round n, we perform an audit on the submission made in round n-1.

To achieve this, we will be editing the following methods in audit.js under the task directory : validateNode() and auditTask()

validateNode()

The purpose of the validateNode() method is to verify whether a node has submitted the correct value, which in this case is "Hello, World!". The method returns true if the value is correct, and false otherwise.

To update the validateNode() method, replace it with the following code block:

async validateNode(submission_value, round) {
    let vote;
    console.log("SUBMISSION VALUE", submission_value, round);

    try {
      if (submission_value == "Hello, World!") {
        vote = true;
      } else {
        vote = false;
      }
    } catch (e) {
      console.error(e);
      vote = false;
    }

    return vote;
}

auditTask()

The auditTask() function calls namespaceWrapper.validateAndVoteOnNodes() and passes the validateNode() method we created initially, along with the current round number.

During each round, participating nodes execute the auditTask() method on each node to verify the validity of the submitted value. In our case, a valid submission value is "Hello, World!". If a node submits a different value, an audit is triggered on K2, and the node responsible may have their stake confiscated.

  async auditTask(roundNumber) {
    await namespaceWrapper.validateAndVoteOnNodes(
      this.validateNode,
      roundNumber,
    );
  }

While the nodes are verifying the data submitted on-chain, they also monitor for any audits raised against a node. They can then vote in favor or against the audit accordingly.