Taints and fading taints

This invention describes a system for protecting sensitive data by tagging it with "taints" and then enforcing rules about where that tainted data can go within a network. Instead of just blocking access at the network edge, specific rules (called assertions) are set up to control data movement at various points inside the network. For example, a rule might say "Red data never leaves my company's cloud space." The claims specifically detail a method where data is tagged, rules are accessed, and these rules are enforced by different network points, which can also communicate and share these data tags.