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A closed/open source server doesn't matter since you can't actually confirm if the open source version is actually running.
by worldsavior 4y ago
A closed/open source server doesn't matter since you can't actually confirm if the open source version is actually running.
- kibwen 4y agoIf it's open source and has a reproducible build, then you can audit the codebase, compute the hash, then verify an attestation from the secure enclave that the code is running in.
- worldsavior 4y agoSo you need to trust the server to return a valid, unmodified hash?
- kibwen 4y agoIn the case of the above, you're not trusting the server, you're only trusting the CPU manufacturer. Attestation happens within the secure enclave inside the CPU, at which point having physical access to the machine doesn't (well, shouldn't, if it's correctly implemented) give you any insight into what code it's running or what data it's operating upon.
- worldsavior 4y agoHow can you know which CPU is running? Also, the software could easily change the output of the security chip (secure enclave is only on apple devices).
- kibwen 4y agoPart of the attestation process involves receiving a cryptographic signature from the CPU vendor. They can only fake it if they break the cryptography. And enclaves (or "trusted execution environments") aren't only on Apple chips, AMD and Intel have their own implementations.
- worldsavior 4y agoBut the CPU is first sending the signature to the OS, thuse enabling the OS to send you something else.