No. So long the code is executing on an uncontrolled device, then you cannot guarantee it'll execute how you intended. So if you make a device, like an iPad, se

No. So long the code is executing on an uncontrolled device, then you cannot guarantee it'll execute how you intended. So if you make a device, like an iPad, seal it to prevent hardware tampering, and ensure no user-triggerable bugs exist, you're all set. There's also remote attestation, like Intel SGX might start to bring. But on existing general-compute devices like PCs, it's a hopeless battle.