The Insider News

Hal's (Im)Perfect Vision[^]:

This is... a small primer for those who don’t quite get all this anti-malware stuff. At its core anti-malware seems pretty straightforward. You take something that can be run (usually an “image” or “executable”, but for sake of the audience we’ll just say App) and run a mathematical algorithm over it that produces an (almost) unique identifier for that App. Generally that unique identifier is called a Hash (because of the technique used). Anytime you run the same algorithm over the same App you get the same Hash.... If someone modifies an app, even slightly, it will have a different Hash. So the Hash tells you exactly what you have.