src/Riak/Node/Builder.php
public function usingPasswordAuthentication($user, $pass = '')
    {
        $this->config->setUser($user);
        $this->config->setPass($pass);
        $this->config->setAuth(true);

        return $this;
    }
public function usingPasswordAuthentication($user, $pass = '')
    {
        $this->config->setUser($user);
        $this->config->setPass($pass);
        $this->config->setAuth(true);

        return $this;
    }
usingPasswordAuthentication

Build nodes with password authentication

User authentication and access rules are only available in Riak versions 2 and above. To use this feature, TSL
is required to communicate with your Riak nodes.

@param $user
@param $pass
@return $this