Comment by ninkendo
2 days ago
I don’t know much about the TPM but if it’s anything like Apple’s Secure Enclave, it should require exponentially longer time after each incorrect PIN past the first one, making it so you can’t reasonably brute force it without getting lucky.
I’m not sure how the typical “two factor” best practices would interpret one of the factors basically self destructing after 10 guesses, but IMO it’s a pretty decent system if done right.
That's not the issue. The TPM isn't blinded in the above description meaning that if someone cracks the TPM they can get your key. Ideally both factors are always required to access the secret.
If you're wondering, yes this is a security issue in practice. There have been TPM vulnerabilities in the past that enabled exfiltration of secrets.