Remote attestation in AMD SEV-SNP
AMD SEV-SNP has two configurations for remote attestation. Standard and extended.
- Standard configuration will request the certificate chain and VCEK certificate directly from AMD's KDS.
- In extended configuration you will have to configure the host to store the ASK, ARK and VCEK (on the PSP?). Then we can request those certificates from the guest via the PSP.
Trusted Computing Base (TCB) in AMD SEV-SNP
The TCB in AMD SEV-SNP confidential VMs is restricted to the AMD hardware and firmware, and the Confidential VM itself.
Attestation flow
Example of a standard attestation in AMD SEV-SNP
quick overview on the software used
The interface used to communicate with the AMD SEV-SNP hardware is from the virTEE project.
We can also use the SEV API directly using ioctls.
Guest VM
Supply a nonce :
rust
// This is a 512 bits array that is signed and included in the attestation report.
// Its purpose could be to add a hash of a public key that would later used or other important
// data that needs to be certified by the attestation report
let user_data: [u8; 64];Requesting the attestation report :
rust
use sev::firmware::guest::*;
// Establishing a connection to the firmware
let mut firmware: Firmware = Firmware::open()?;
// Request a standard attestation report
let attestation_report: AttestationReport = firmware.get_report(None)