One way is x86. Intel’s chips have SGX (software guard extensions) that allows code to run in “enclaves” that outside code can’t access. You can send data into

One way is x86. Intel’s chips have SGX (software guard extensions) that allows code to run in “enclaves” that outside code can’t access. You can send data into the enclave and read what it spits out, but you can’t inspect (debug) it.