1.8 KiB
Proof of Ownership
A cluster owner needs a way to prove a cluster belongs to them, while a third-party needs to be able to verify the owner's claims. For that, the owner generates a private/public key pair.
During constellation init, the cluster will generate its own private/public key pair, and send back a signing request for the public key.
The signed public key is measured into a PCR, so the binding of the private/public key to the cluster can be verified through remote attestation.
The cluster is now able to sign data using its own private key.
A third-party can verify a cluster belongs to a specific person in three steps:
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Verify the signature of data provided by the third-party and signed by the cluster
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Verify the cluster's public key was signed by the owner
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Verify the public key is measured into a PCR by validating the cluster's attestation statement
Workflow
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Cluster owner generates a private/public key pair
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The Constellation cluster generates its own private/public key pair and requests the owner to sign the public key during
constellation init -
Constellation measures the signed public key into PCR[11] (previously used for ownerID)
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A third-party requests an attestation from the verification service, providing some data to be signed
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The verification service signs the data using its private key
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The verification service returns: attestation document + data signature + signed public key
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The third-party verifies the public key signature using the owner's public key
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The third-party calculates the expected PCR[11] using the signed public key and validates the attestation document
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The data signature is verified, and if successful proving ownership of the cluster
Encoding
The signed public key measured into PCR[11] is DER encoded. TODO: Add exact encoding specification