It doesn't mitigate untrusted software, but an interesting approach to tamper resistance can be found in Infineon SLE78 security controllers (for smart cards, e

It doesn't mitigate untrusted software, but an interesting approach to tamper resistance can be found in Infineon SLE78 security controllers (for smart cards, etc). They run dual CPUs out-of-sync and compare results after each instruction. http://www.infineon.com/cms/en/product/chip-card-and-security-ics/security-controller-contact-based/sle-78-solid-flash-tm-family-digital-security-controller/channel.html?channel=db3a30431ce5fb52011d47b166342af0 http://www.infineon.com/cms/en/product/chip-card-and-securit...