Messages in this thread | | | From | Dionna Amalie Glaze <> | Date | Wed, 16 Aug 2023 12:38:38 -0700 | Subject | Re: [PATCH v2 3/5] virt: sevguest: Prep for kernel internal {get, get_ext}_report() |
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> Definitely, instead it was this comment from James that gave me pause: > > "To get a bit off topic, I'm not sure derived keys are much use. The > problem is in SNP that by the time the PSP does the derivation, the key > is both tied to the physical system and derived from a measurement too > general to differentiate between VM images (so one VM could read > another VMs stored secrets)." >
Key derivation on AMD SEV-SNP is not necessarily tied to a physical system with the introduction of VLEK-based attestation. It's now tied to a CSP's fleet of machines. We can use key derivation in the SVSM as a basis for further key derivation based on measurement registers, so the utility increases to provide something like persisted sealed data that can only be unsealed when the SVSM witnesses a particular runtime measurement configuration. We can use NIST 800-90A Rev. 1 for combining keys from the PSP with measurement register values for example.
> http://lore.kernel.org/r/c6576d1682b576ba47556478a98f397ed518a177.camel@HansenPartnership.com
-- -Dionna Glaze, PhD (she/her)
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