1. A system for protecting computers against cache poisoning, the system comprising: a cache-entity table configured to maintain a plurality of associations between a plurality of data caches and a plurality of entities, wherein each of said caches is associated with a different one of said entities; and a cache manager configured to receive data that is associated with any of said entities and store said received data in any of said caches that said cache-entity table indicates is associated with said entity, and receive a data request that is associated with any of said entities and retrieve said requested data from any of said caches that said cache-entity table indicates is associated with said requesting entity, wherein any of said cache-entity table and cache manager are implemented in either of computer hardware and computer software embodied in a computer-readable medium.