What mjg59 says. The benchmarks are against a vTPM, that was what I had access to, and it's the environment I'm implementing the RATS side in.
replyWorth adding that not every outbound connection needs to go through the TPM (IMO). It's for the handful of services where the machine-identity actually matters, a secret store, or an HSM releasing key material onto an attested confidential VM, in my case.
You didn't really go into actually verifying the machine identity - obviously if you have a trusted mechanism to do that in advance then that's easy enough, but otherwise you'd want something like https://github.com/google/go-attestation and then to use control plane APIs to identify the vTPM EK to tie the TPM to the VM.
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