AFAICT the TPM spec[1] doesn't (yet) allow it, or if it doesn't forbid it it certainly doesn't require it and it's not even mentioned explicitely. Some HSMs do,

AFAICT the TPM spec[1] doesn't (yet) allow it, or if it doesn't forbid it it certainly doesn't require it and it's not even mentioned explicitely. Some HSMs do, but those are a lot more expensive (and a lot more capable). EG the YubiHSM-2 does, but it's $650. [1] https://trustedcomputinggroup.org/resource/tpm-library-specification/ https://trustedcomputinggroup.org/resource/tpm-library-speci...