The software needed to run all of Google’s services—from Google Search to Gmail to Google Maps—runs to an estimated two billion lines of code. By comparison, Microsoft’s Windows operating system, one of the most complex software tools ever built for a single computer, is estimated to contain some fifty million lines of code. McAfee never found hard evidence that China’s attackers altered the source code at any of their targets. But with so many of China’s victims in denial that they had been hacked, the only certainty was uncertainty.
