Sealed

A sealed machine is a confidential virtual machine on an AMD EPYC processor with SEV-SNP. Its memory is encrypted inside the CPU, under a key the host never sees.

The disk of a sealed machine is encrypted inside the machine. The key is released only after the machine proves, with an attestation report signed by AMD's secure processor, exactly what it booted. No key is ever baked into an image, and every machine has its own.

Traffic between your machines, and between your machines and your own devices, travels a tunnel that ends inside each machine. Its key exchange is the hybrid post-quantum group X25519MLKEM768.

What sealing does not cover

• Physical attacks on the memory bus. An interposer on a server's memory can defeat SEV-SNP, as TEE.fail showed, and AMD treats it as out of scope.
• Side channels. The host still controls paging and scheduling, so it can see which pages a machine touches, and when.
• Availability. Whoever runs a server can always stop or slow a machine.
• Metadata. How much traffic flows, when, and between which servers stays visible.

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