Simon Willison’s Weblog

Whenever you build a security system that relies on detection and identification, you invite the bad guys to subvert the system so it detects and identifies someone else. [...] Build a detection system, and the bad guys try to frame someone else. Build a detection system to detect framing, and the bad guys try to frame someone else framing someone else. Build a detection system to detect framing of framing, and well, there's no end, really.

— Bruce Schneier