hardware security

The CPU does work it later throws away, but the cache remembers. The strong answer explains that one sentence precisely, then turns it into isolation decisions for shared infrastructure.

The algorithm is correct and the key never leaves the chip. The attacker reads it anyway from how long, how loud or how hot the computation is, or breaks it by making the chip skip one instruction.

They all promise 'hardware security'. They protect different things from different attackers, and choosing well means knowing who you are defending against.