sandbox/proof/hardware/2026-10-21-sev-snp/README.md

@@ -0,0 +1,56 @@
+# A confidential run on SEV-SNP hardware, 2026-10-21
+
+The report-data binding of SPEC §7.6, exercised on genuine AMD silicon and
+verified by a party other than the host.
+
+## What ran
+
+- **Platform:** a confidential VM with AMD SEV-SNP, on an AMD Milan processor
+  (`n2d-standard-2`, image `ubuntu-2404-noble-amd64-v20261016`). It was created
+  for the run and deleted after it.
+- **Inside the guest:** the reference host
+  ([`confidential_run`](../../../sandbox-rs/crates/sandbox-runtime/examples/confidential_run.rs)).
+  It took a report through `configfs-tsm` (the kernel named its provider
+  `sev_guest`) and sealed an S6 run. Its `report_data` is the run binding:
+  the unit, the receipt, the outcome, and a 32-byte challenge chosen by the
+  party that started the run ([`challenge.hex`](challenge.hex)).
+- **The report:** version 5, 1184 bytes, signed with the chip's VCEK. It
+  travels in the attestation as `tee.report_hex`.
+
+## What it shows
+
+Verified away from the guest, from these files alone:
+
+```text
+cd ../../../sandbox-rs
+cargo run -p sandbox-runtime --example verify_run -- \
+  ../proof/hardware/2026-10-21-sev-snp/attestation.json \
+  "$(cat ../proof/hardware/2026-10-21-sev-snp/challenge.hex)" \
+  ../proof/hardware/2026-10-21-sev-snp/vcek.der
+```
+
+- The report verifies through the VCEK. Its `report_data` is the binding of
+  this attestation's unit, receipt and outcome, and of the challenge issued.
+- It is refused for any other challenge, and without one.
+- An attestation whose outcome is changed is refused: the AMD signature covers
+  the outcome through the binding.
+
+The VCEK ([`vcek.der`](vcek.der)) was fetched from AMD's KDS by the chip id and
+reported TCB inside the report. It chains to AMD's root
+([`cert_chain.pem`](cert_chain.pem): `SEV-Milan`, then `ARK-Milan`):
+
+```text
+openssl x509 -inform der -in vcek.der -out vcek.pem
+openssl verify -CAfile <ARK-Milan> -untrusted <SEV-Milan> vcek.pem
+```
+
+The ARK's SHA-256 fingerprint is
+`69:D0:63:B4:53:44:D2:6A:2E:94:E1:F4:21:0D:E4:9E:F5:55:30:82:87:D4:C1:74:44:5C:95:63:9A:54:0B:CD`.
+Compare it with the one AMD publishes, not with this file.
+
+## What it does not show
+
+- The unit is a fixed placeholder. This exercises the binding and the verifier
+  on real hardware, not an executor's isolation of a workload.
+- The receipt and Supervisor keys are fixed development keys. The trust here
+  rests on the hardware report, not on those signatures.

sandbox/proof/hardware/2026-10-21-sev-snp/attestation.json

@@ -0,0 +1,29 @@
+{
+  "audit_prev": null,
+  "devices": [
+    {
+      "class": "Cpu",
+      "driver": "host",
+      "model": "confidential guest"
+    }
+  ],
+  "finished_at_us": 1792601988753099,
+  "grants_id": "b3:ej-h9yIoVIBjnlA-OMDiy95_Jlk7nqn6djvXYNv035w",
+  "host_id": "gcp-confidential-vm",
+  "image_id": "b3:sfsM4tYpFQT10UkAZVEdN5C2user1jDf-76b0oYeI8o",
+  "journal_root": null,
+  "locality": null,
+  "mechanism": null,
+  "outcome": "Completed",
+  "receipt_id": "b3:kCkhM2_jsKJyBwLL17ivdqhPhyPEIJaWjPUVDFRR6hU",
+  "started_at_us": 1792601988753098,
+  "tee": {
+    "challenge_hex": "f9a4ec56a429a6fed42839517a03745723a8317a70b737dbd78b98087ebfa6b7",
+    "kind": "SevSnp",
+    "measurement_hex": "0e017d2fba7c4964575fdd8c770061abf07f0753148d030f94e969a2d1fa5a5747ba0ced9174f2d44b5f6663fa2de00f",
+    "report_hex": "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",
+    "tcb": "0xde1d000000000004"
+  },
+  "tier": "S6",
+  "unit_id": "b3:StLoFp1GgfFDM6RVELdOlbduOMrjpLZGE6kSdYoLFNg"
+}

sandbox/proof/hardware/2026-10-21-sev-snp/challenge.hex

@@ -0,0 +1 @@
+f9a4ec56a429a6fed42839517a03745723a8317a70b737dbd78b98087ebfa6b7

sandbox/sandbox-rs/Cargo.lock

@@ -1886,6 +1886,7 @@ dependencies = [
  "sandbox-meter",
  "sandbox-schema",
  "sandbox-tee",
+ "serde_json",
  "thiserror 2.0.20",
 ]
 

sandbox/sandbox-rs/crates/sandbox-runtime/Cargo.toml

@@ -21,3 +21,4 @@ thiserror.workspace = true
 
 [dev-dependencies]
 p256.workspace = true
+serde_json.workspace = true

sandbox/sandbox-rs/crates/sandbox-runtime/examples/confidential_run.rs

@@ -0,0 +1,93 @@
+//! Seal a confidential run on real hardware and verify it as a third party
+//! would (SPEC §7.6).
+//!
+//! Run as root inside an SEV-SNP guest with `configfs-tsm`:
+//!
+//! ```text
+//! confidential_run <challenge-hex> <vcek.der>
+//! ```
+//!
+//! `vcek.der` is the chip's VCEK, from AMD's KDS. The host seals an S6 run whose
+//! report the platform signs over the run's binding and the challenge. The
+//! attestation is then verified through the VCEK alone, against the verifier's
+//! own challenge, and against another challenge, which must fail. The run's
+//! unit is a fixed placeholder: what this exercises is the binding and the
+//! verifier on genuine silicon. It prints the verdicts and the attestation as
+//! JSON.
+
+use ed25519_dalek::SigningKey;
+use sandbox_attest::{DeviceIdentity, Outcome};
+use sandbox_capability::Grants;
+use sandbox_meter::{DeviceEnergy, Provenance};
+use sandbox_runtime::{verify_run_evidence, Host, RunReport, TeeConfig};
+use sandbox_schema::{ContentId, DeviceClass, Tier};
+use sandbox_tee::policy::{TeeAnchor, TeePolicy};
+use sandbox_tee::provider::ConfigfsTsmProvider;
+
+fn main() {
+    let args: Vec<String> = std::env::args().collect();
+    let (Some(challenge_hex), Some(vcek_path)) = (args.get(1), args.get(2)) else {
+        eprintln!("usage: confidential_run <challenge-hex> <vcek.der>");
+        std::process::exit(2);
+    };
+    let challenge: [u8; 32] =
+        hex::decode(challenge_hex).ok().and_then(|v| v.try_into().ok()).expect("a 32-byte hex challenge");
+    let der = std::fs::read(vcek_path).expect("read the VCEK");
+    // The P-384 public point in the certificate's SubjectPublicKeyInfo: the
+    // BIT STRING `03 62 00 04` followed by x ‖ y.
+    let at = der.windows(4).position(|w| w == [0x03, 0x62, 0x00, 0x04]).expect("a P-384 point in the VCEK");
+    let vcek = p384::ecdsa::VerifyingKey::from_sec1_bytes(&der[at + 3..at + 3 + 97]).expect("a P-384 key");
+    let anchor = TeeAnchor::SevSnp(vcek);
+    let policy = TeePolicy::sev_snp_baseline();
+
+    let host = Host::new("gcp-confidential-vm", "steward.hardware-check", SigningKey::from_bytes(&[1; 32]), SigningKey::from_bytes(&[2; 32]))
+        .with_tee(TeeConfig { provider: Box::new(ConfigfsTsmProvider::default()), policy: policy.clone(), anchor: anchor.clone() });
+    let report = RunReport {
+        device_energy: vec![DeviceEnergy { class: DeviceClass::Cpu, measured_uj: None, estimated_uj: 1, provenance: Provenance::Estimator }],
+        device_identity: vec![DeviceIdentity { class: DeviceClass::Cpu, model: "confidential guest".into(), driver: "host".into() }],
+        outcome: Outcome::Completed,
+        journal: None,
+        storage: None,
+    };
+    let now_us = std::time::SystemTime::now().duration_since(std::time::UNIX_EPOCH).map_or(0, |d| d.as_micros() as u64);
+    let sealed = match host.seal_run_with_mechanism(
+        ContentId::of_bytes(b"hardware check unit"),
+        ContentId::of_bytes(b"hardware check image"),
+        &Grants::default(),
+        Tier::S6,
+        report,
+        0,
+        [0; 8],
+        now_us,
+        now_us + 1,
+        None,
+        Some(challenge),
+    ) {
+        Ok(s) => s,
+        Err(e) => {
+            println!("{}", serde_json::json!({ "sealed": false, "error": e.to_string() }));
+            std::process::exit(1);
+        }
+    };
+    let a = &sealed.attestation;
+    let tee = a.tee.as_ref().expect("an S6 run carries TEE evidence");
+    let verified = verify_run_evidence(a, Some(&challenge), &policy, &anchor);
+    let mut other = challenge;
+    other[0] ^= 1;
+    let refused_other = verify_run_evidence(a, Some(&other), &policy, &anchor).is_err();
+    let refused_none = verify_run_evidence(a, None, &policy, &anchor).is_err();
+    println!(
+        "{}",
+        serde_json::json!({
+            "sealed": true,
+            "verified": verified.is_ok(),
+            "verify_error": verified.err().map(|e| e.to_string()),
+            "refused_another_challenge": refused_other,
+            "refused_no_challenge": refused_none,
+            "kind": format!("{:?}", tee.kind),
+            "measurement_hex": tee.measurement_hex,
+            "tcb": tee.tcb,
+            "attestation": a,
+        })
+    );
+}

sandbox/sandbox-rs/crates/sandbox-runtime/examples/verify_run.rs

@@ -0,0 +1,46 @@
+//! Verify a sealed run's TEE evidence as a third party (SPEC §7.6): from the
+//! attestation, the challenge the verifier issued, and the platform's anchor,
+//! with nothing from the host that sealed it.
+//!
+//! ```text
+//! verify_run <attestation.json> <challenge-hex> <vcek.der>
+//! ```
+//!
+//! `vcek.der` is the chip's VCEK, as AMD's KDS issues it. The run is verified
+//! against the challenge, and must be refused against any other challenge and
+//! against none. Exits non-zero unless all three hold.
+
+use sandbox_attest::Attestation;
+use sandbox_runtime::verify_run_evidence;
+use sandbox_tee::policy::{TeeAnchor, TeePolicy};
+
+fn main() {
+    let args: Vec<String> = std::env::args().collect();
+    let (Some(path), Some(challenge_hex), Some(vcek_path)) = (args.get(1), args.get(2), args.get(3)) else {
+        eprintln!("usage: verify_run <attestation.json> <challenge-hex> <vcek.der>");
+        std::process::exit(2);
+    };
+    let attestation: Attestation =
+        serde_json::from_str(&std::fs::read_to_string(path).expect("read the attestation")).expect("an attestation");
+    let challenge: [u8; 32] =
+        hex::decode(challenge_hex.trim()).ok().and_then(|v| v.try_into().ok()).expect("a 32-byte hex challenge");
+    let der = std::fs::read(vcek_path).expect("read the VCEK");
+    let at = der.windows(4).position(|w| w == [0x03, 0x62, 0x00, 0x04]).expect("a P-384 point in the VCEK");
+    let anchor = TeeAnchor::SevSnp(p384::ecdsa::VerifyingKey::from_sec1_bytes(&der[at + 3..at + 3 + 97]).expect("a P-384 key"));
+    let policy = TeePolicy::sev_snp_baseline();
+
+    let verified = verify_run_evidence(&attestation, Some(&challenge), &policy, &anchor);
+    let mut other = challenge;
+    other[31] ^= 0x80;
+    let refused_other = verify_run_evidence(&attestation, Some(&other), &policy, &anchor).is_err();
+    let refused_none = verify_run_evidence(&attestation, None, &policy, &anchor).is_err();
+    match &verified {
+        Ok(v) => println!("verified: {:?} run, measurement {}", v.kind, hex::encode(v.measurement)),
+        Err(e) => println!("NOT verified: {e}"),
+    }
+    println!("refused for another challenge: {refused_other}");
+    println!("refused without a challenge: {refused_none}");
+    if verified.is_err() || !refused_other || !refused_none {
+        std::process::exit(1);
+    }
+}

sandbox/sandbox-rs/crates/sandbox-tee/src/policy.rs

@@ -126,8 +126,10 @@ pub fn verify_snp(
     }
     let report = SnpReport::parse(report_bytes)?;
 
-    // 0. Version: this verifier models the v2 field layout (and v3, whose
+    // 0. Version: this verifier models the v2 field layout, which later
-    // checked fields share those offsets). Reject a version it does not model
+    // versions keep for the fields checked here: a v5 report from SEV-SNP
+    // hardware verified (sandbox/proof/hardware/2026-10-21-sev-snp). Reject a
+    // version it does not model
     // rather than silently misinterpret fields at the wrong offsets.
     const MIN_MODELED_VERSION: u32 = 2;
     if report.version < MIN_MODELED_VERSION {