SBOM Attestation for Software Health

1. Mechanism

A device participating in the disclosed architecture carries a hardware-rooted identity (TPM 2.0, secure element, or equivalent) and a build-time-issued SBOM that enumerates every software component installed on the device, including operating system, firmware, application binaries, dynamic libraries, interpreted-language packages, container images, and configuration manifests. Each component entry carries a name, a version, a cryptographic hash (SHA-256 minimum, with optional SHA-384 or SHA-512 for high-assurance applications), a license identifier, a supplier identifier, and a dependency edge set. The SBOM is serialized in a standards-conformant format (SPDX 2.3 or CycloneDX 1.5) and signed by the build authority using a key whose certificate chains to a governance-declared trust anchor.

At deployment, the device verifies the SBOM signature against the trust anchor, verifies that the on-disk components match the SBOM hashes, and binds the verified SBOM to its hardware identity by sealing a measurement of the SBOM into the device's secure element. The sealed measurement is then exported as a credentialed observation: a record carrying the device identity, the SBOM measurement, the build authority signature, the deployment-time verification result, and the device's secure-element attestation signature. Downstream consumers receive this credentialed observation and admit it into the five-property chain alongside other health-monitoring evidence.

At runtime, the device revalidates the SBOM at governance-declared intervals (typically every boot, plus a continuous integrity-measurement loop sampling the running process set every 60 seconds, plus an event-driven revalidation triggered by package installation, kernel module load, or configuration mutation). Each revalidation produces a fresh credentialed observation. Deviation between the running software and the signed SBOM — an unmeasured binary on disk, an unknown library mapped into a process, a dynamically-loaded module with no SBOM entry — is itself emitted as a credentialed observation with explicit deviation analysis, so that downstream consumers can evaluate the deviation against the device's admissibility profile.

The revalidation pipeline is structured as a producer-consumer loop in which the integrity-measurement agent (running either in the kernel, in a privileged user-space daemon, or inside a confidential-computing enclave) emits measurement records over a local audit channel; the channel is consumed by the attestation service, which compares each record against the sealed SBOM and emits credentialed observations to the upstream collector. The agent maintains a denylist of known-bad hashes derived from the governance-issued revocation feed, an allowlist derived from the signed SBOM, and a graylist of components observed but not yet classified. Graylist entries trigger an out-of-band reconciliation request to the build authority, which either returns an updated SBOM that includes the new component (the typical case for legitimate hot-patch deployments) or returns a rejection that escalates the graylist entry into a full deviation observation.

The credentialed-observation envelope carries, in addition to the SBOM measurement and signature, a monotonic counter rooted in the secure element, a wall-clock timestamp, and a correlation identifier that links the observation to the device's prior observation stream. The monotonic counter prevents replay of stale observations after a device is rolled back to an earlier software state; the wall-clock timestamp supports freshness windowing; and the correlation identifier supports stream-level lineage analysis by downstream consumers who maintain a per-device observation history. The envelope is wire-compatible with the Internet-Engineering-Task-Force RATS (Remote Attestation Procedures) architecture so that existing relying-party tooling may be reused without modification.

2. Operating Parameters

CVE matching operates as a continuous query against the signed SBOM. A governance-maintained vulnerability feed (NVD, vendor advisories, private-sector threat intelligence) is converted to a normalized matching predicate over component name, version range, and configuration. The matching engine produces credentialed CVE-match observations, each carrying the matched component, the CVE identifier, the CVSS vector, the exploitability assessment, and the time at which the match was first asserted. Matching operates with a target latency under 60 seconds from advisory publication to credentialed observation issuance for monitored fleets, and under 24 hours for the long tail.

SBOM revocation is treated structurally. When a component, a build, or an entire supplier is determined to be compromised, the governance chain issues a signed revocation record bound to the affected SBOM component identifiers and version ranges. Devices receiving the revocation record evaluate their sealed SBOM against the revocation predicate and emit a credentialed revocation-affected observation. The revocation propagates to all downstream consumers of the device's earlier credentialed observations through the lineage property of the chain, so that prior decisions made under the now-revoked SBOM can be re-evaluated. Propagation latency is budgeted at under 15 minutes from governance issuance to fleet acknowledgement for high-priority revocations.

Storage and bandwidth are tuned for resource-constrained embodiments. A typical SBOM for an embedded device is 50 to 500 KB compressed; a typical server SBOM is 2 to 20 MB. The credentialed-observation format supports both inline SBOM transport and reference-by-hash transport, where only the SBOM hash and a fetch URL are carried in the observation and the full SBOM is retrieved on demand from a content-addressed store. Reference-by-hash transport reduces per-observation overhead to under 2 KB.

Cryptographic parameters are governance-declared rather than hard-coded. Signing keys may be RSA-3072, RSA-4096, ECDSA-P256, ECDSA-P384, or Ed25519, with post-quantum candidates (Dilithium, Falcon, SPHINCS+) admitted through the same governance schema once standardized. Hash algorithms are SHA-256 minimum with SHA-384 and SHA-512 admitted; for high-assurance applications the SBOM may carry parallel hashes under multiple algorithms to support cryptographic agility during a future algorithm transition. Trust-anchor rotation is supported through an overlap window during which both the outgoing and incoming anchors are admissible; signed cross-certificates bridge the rotation so that observations issued during the window remain verifiable by relying parties on either side of the transition.

Operational availability targets call for the attestation pipeline to sustain a steady-state observation rate of at least one observation per device per minute under nominal load and to absorb burst rates of at least ten observations per device per minute during deployment, configuration mutation, or active-incident response without dropping or aggregating observations. Aggregation, when bandwidth-constrained, is performed at the upstream collector rather than at the device, so that the per-device observation stream remains a verbatim record of the local agent's measurements. The upstream collector applies governance-declared aggregation rules and emits its own credentialed aggregation observation that references the underlying per-device observations by hash.

3. Alternative Embodiments

A constrained-device embodiment targets microcontroller-class platforms with kilobytes of RAM and limited flash. The SBOM is reduced to a hashed manifest of firmware images and is verified once per boot against a measurement stored in a secure element; runtime revalidation is approximated by periodic firmware-integrity measurement rather than full process-set introspection. CVE matching is performed off-device by a fleet-management gateway that holds the SBOMs on behalf of the constrained devices.

A server-class embodiment performs full continuous attestation: every running process is mapped to its on-disk binary, every dynamically-loaded library is resolved to its SBOM entry, every container image is verified against its signed manifest, and every configuration mutation is recorded as a credentialed observation. Server embodiments typically integrate with a confidential-computing boundary (Intel TDX, AMD SEV-SNP, ARM CCA) so that the attestation pipeline itself runs inside an isolated execution environment.

A federated embodiment composes per-device SBOM attestations into fleet-level credentialed observations. The fleet authority aggregates per-device observations, computes fleet-wide CVE exposure, and issues a fleet-level credentialed observation that downstream operators (regulators, customers, insurers) can admit without exposing per-device telemetry. The architecture is agnostic to whether attestation happens on-device, in a gateway, in a cloud control plane, or in a federated aggregator, provided the credentialed-observation interface is honored at each layer.

A privacy-preserving embodiment exposes the SBOM measurement and CVE-match summary without exposing the full SBOM payload. Zero-knowledge predicate proofs allow the device to demonstrate that its SBOM satisfies a relying-party's admissibility predicate (no components on a designated denylist, all components above a minimum version, no unpatched critical CVEs) without revealing the component list itself. This embodiment supports regulated industries in which the operator is required to demonstrate compliance to an auditor while withholding inventory detail from competitive disclosure. The proof artifact is itself a credentialed observation, signed by the device's secure element and bound to the underlying SBOM measurement by a hash commitment.

4. Composition With Five-Property Chain

The signed SBOM is the credentialed observation that anchors software identity in the chain. Identity is supplied by the device's hardware-rooted secure element; lineage is established by the build authority's signature and the deployment-time verification record; admissibility is governed by the freshness of the SBOM measurement and the absence of unresolved revocations; corroboration is supplied by cross-fleet observations of the same software components and by independent reproducible builds; and revocability is honored through the governance chain's signed revocation records.

SBOM observations compose with other health-monitoring primitives. A device with a current, unrevoked SBOM but a failing tamper-evident seal observation is admissible for fewer downstream decisions than one with both signals nominal; a device with a current SBOM but an outstanding CVE match against a critical component may be admissible only for read-only operations until the CVE is patched and a fresh SBOM is sealed. The architecture exposes these composition rules as governance-declared admissibility profiles rather than as hard-coded device behavior, so that the same device can serve different downstream consumers with different risk tolerances.

Composition with reproducible-build evidence strengthens the corroboration property. When the build authority publishes signed reproducibility attestations — independent rebuilds of the same source tree producing byte-identical artifacts with matching hashes — the SBOM observation references the reproducibility attestation, and downstream consumers admitting the SBOM observation transitively rely on the rebuild evidence. The lineage chain captures the full provenance graph from source commit through build to deployment to runtime measurement, so that any compromise discovered at any layer can be propagated through revocation to all derived observations.

Composition with incident-response workflows exposes the SBOM as a structured input to forensic analysis. When a security event occurs, the per-device SBOM observation stream provides an unforgeable timeline of software state across the affected fleet; investigators query the stream to identify which devices ran the suspect component during the incident window, which devices have been patched, and which remain exposed. The same query infrastructure supports proactive hunting against newly-disclosed vulnerabilities before public CVE assignment, by matching against vendor-private threat intelligence admitted through the governance-declared advisory feed.

5. Distinction from Prior Art

The disclosed architecture is distinct from build-time SBOM generation followed by static publication, in which the SBOM is produced once, posted to a registry, and never re-evaluated against the running device. Static publication satisfies the bookkeeping requirements of EO 14028 but provides no structural guarantee that the device in the field corresponds to the published SBOM, no continuous revalidation, and no propagation path for revocations. The disclosed architecture binds the SBOM to device identity, revalidates continuously, and treats revocation as a first-class governance event.

The architecture is also distinct from remote attestation systems that report platform measurements without semantic content. Such systems prove that a device booted a particular kernel image but offer no enumeration of the software composition, no CVE matching, and no license or supplier accountability. The disclosed architecture combines hardware-rooted attestation with semantically-rich SBOM content, so that downstream consumers receive both proof of platform integrity and an enumerated bill of materials suitable for vulnerability and license analysis.

Finally, the architecture is distinct from vulnerability scanners that operate against unsigned, externally-collected inventories. Such scanners cannot distinguish a genuine inventory from one fabricated by a compromised host. The disclosed architecture's signed, identity-bound SBOM is unforgeable under the threat model of the secure element, providing a structural guarantee that scanners operating on unsigned inventories cannot match.

6. Disclosure Scope

This disclosure covers the signed-SBOM credentialed-observation format, the build-time signing process, the deployment-time verification and sealing process, the runtime revalidation loop, the CVE-matching engine, the governance-issued revocation record, and the propagation of revocation through the lineage property of the five-property chain. The disclosure is not limited to a specific SBOM serialization format; SPDX, CycloneDX, and any future format admitted through the governance-declared schema registry fall within scope. Likewise, the disclosure is not limited to a specific secure-element technology; TPM 2.0, hardware security modules, secure enclaves, and emerging confidential-computing primitives are all admissible identity roots.

The disclosed architecture aligns with the regulatory direction expressed in Executive Order 14028 (improving the nation's cybersecurity), the NTIA minimum elements for an SBOM, and OMB Memorandum M-22-18 (enhancing the security of the software supply chain through secure software development practices). Defense, civilian critical infrastructure, regulated medical devices, financial systems, and consumer IoT all benefit from the disclosed architecture, and as SBOM standards mature the architecture's governance-declared schema registry admits the new standards without modification of the core mechanism.