====================================================================== Secure Firmware Signing Workflow Diagram (DXF) ====================================================================== DEFINITION ---------------------------------------- The Secure Firmware Signing Workflow Diagram (DXF) is a vector-based technical drawing in AutoCAD DXF format that visually models the end-to-end cryptographic process for authenticating and integrity-protecting firmware updates in mine automation systems. It depicts roles, artifacts, cryptographic operations, and trust boundaries involved in signing, verifying, and deploying firmware across embedded controllers, gateways, and cloud services. The diagram serves as both a compliance artifact and engineering reference within the Mine Automation Cybersecurity Framework. OVERVIEW ---------------------------------------- This DXF resource operationalizes cryptographic assurance principles—specifically code signing, chain-of-trust establishment, and secure key management—tailored to the constrained, safety-critical environments of mining automation infrastructure. It maps standardized workflow stages: firmware build and hashing, offline private key signing using Hardware Security Modules (HSMs), certificate-based attestation (e.g., X.509 PKI), secure distribution via signed manifests, and runtime verification on edge devices (e.g., PLCs, RTUs, or autonomous haul trucks). The diagram explicitly separates trusted (air-gapped signing environments) and untrusted (OT network, cloud update servers) zones, annotates cryptographic algorithms (e.g., ECDSA P-384, SHA-384), and defines validation checks such as signature verification, certificate revocation status (OCSP/CRL), and firmware image hash matching. As part of the Mine Automation Cybersecurity Framework, it aligns with IEC 62443-3-3 SL2 requirements for secure software update mechanisms and supports auditability, incident response forensics, and regulatory reporting by providing a machine-readable, version-controlled visual specification. KEY COMPONENTS ---------------------------------------- 1. Offline HSM-Based Signing Station 2. X.509 Certificate Authority Hierarchy 3. Signed Firmware Manifest (CBOR/JSON-LD) APPLICATIONS ---------------------------------------- - Cybersecurity compliance auditing for mining OEMs - Secure OTA (Over-the-Air) update pipeline design - Threat modeling and attack surface analysis for OT firmware supply chain KEY FORMULAS ---------------------------------------- Firmware Integrity Check: H(FW_image) == H_recovered_from_signature × Verify(Sig, PubKey, H(FW_image)) -> Verifies that the firmware image hash matches the one cryptographically bound to the signature using the corresponding public key Signature Validation Confidence Score: SVC = (1 − P_revoked) × (1 − P_expired) × (1 − P_compromised_key) -> Quantifies probabilistic trust in a firmware signature based on certificate revocation status, validity period, and key compromise risk indicators RELATED CONCEPTS ---------------------------------------- - Code Signing Certificate - Hardware Security Module (HSM) - IEC 62443-3-3 REFERENCES ---------------------------------------- Mine Automation Cybersecurity Framework v2.1 (https://www.minecybersecurity.org/framework/v2.1) NIST SP 800-193: Platform Firmware Resilience Guidelines (https://csrc.nist.gov/publications/detail/sp/800-193/final) ISO/IEC 17025:2017 — General requirements for the competence of testing and calibration laboratories (for HSM validation) (https://www.iso.org/standard/66934.html) TAGS ---------------------------------------- DXF, firmware-security, mining-OT, code-signing, cybersecurity-framework