Sean Gallagher erklärt auf Ars Technica die Entwicklung von XKeyscore, seit den Ursprüngen von Carnivore und Narus:

XKeyscore takes the data brought in by the packet capture systems connected to the NSA’s taps and processes it with arrays of Linux machines. The Linux processing nodes can run a collection of „plugin“ analysis engines that look for content in captured network sessions; there are specialized plugins for mining packets for phone numbers, e‑mail addresses, webmail and chat activity, and the full content of users’ Web browser sessions.