{ "version": "0.1", "description": "Station X Trust Score methodology v0.1. Scores a host 0-100 from externally observed, point-in-time TLS behaviour. Three of five dimensions (PQC Deployment, TLS Configuration, Certificate Lifecycle) are DIRECT measurements of the handshake and certificate. Two dimensions (Crypto-Agility, Dependency Risk) are DECLARED PROXIES: at v0.1 they infer posture from transport-layer signals and their stated limits are published below, not hidden. Any score is reproducible bit-for-bit from its stored observation row. Real-organisation scores are external observations of public endpoints (TLS handshakes only), presented as point-in-time facts, not opinions.", "bands": { "ultra_min": 75, "hybrid_min": 50 }, "dimensions": [ { "key": "pqc_deployment", "label": "PQC Deployment", "weight": 35, "measurement": "direct", "description": "Does the endpoint actually perform a hybrid post-quantum key exchange? Measured directly by offering the X25519MLKEM768 hybrid group (FIPS 203 ML-KEM + X25519) in a real handshake and reading the negotiated group. This is the flagship signal: it is the only dimension that speaks to harvest-now-decrypt-later resistance, which is why it carries the most weight.", "signals": [ { "key": "pqc_hybrid_kex_negotiated", "label": "Hybrid PQC key exchange negotiated", "max": 85, "description": "Full points when the server negotiates X25519MLKEM768 when offered a hybrid ClientHello. Zero otherwise. Directly observed from the negotiated group (crypto/tls ConnectionState.CurveID)." }, { "key": "pqc_only_capable", "label": "PQC-only handshake accepted", "max": 15, "description": "Full points when a handshake offering ONLY the hybrid PQC group succeeds — evidence PQC is genuinely deployed rather than merely tolerated alongside a classical fallback." } ] }, { "key": "tls_configuration", "label": "TLS Configuration", "weight": 20, "measurement": "direct", "description": "Baseline transport hygiene, measured directly: modern protocol floor and ceiling, and authenticated-encryption cipher selection.", "signals": [ { "key": "tls13_supported", "label": "TLS 1.3 supported", "max": 45, "description": "Full points when TLS 1.3 is negotiated. TLS 1.3 is also the floor required for the hybrid PQC group." }, { "key": "no_legacy_protocols", "label": "No legacy TLS (1.0/1.1)", "max": 35, "description": "Full points when handshakes offering a TLS 1.0 or 1.1 ceiling are refused (protocol floor is \u003e= TLS 1.2)." }, { "key": "aead_cipher", "label": "AEAD cipher negotiated", "max": 20, "description": "Full points when the negotiated cipher is AEAD (AES-GCM or ChaCha20-Poly1305); non-AEAD (CBC) scores zero." } ] }, { "key": "crypto_agility", "label": "Crypto-Agility", "weight": 15, "measurement": "declared_proxy", "description": "DECLARED PROXY (v0.1). We do not have inside visibility into an organisation's ability to rotate cryptographic primitives, so v0.1 infers it from two external transport signals: certificate rotation cadence and protocol currency. LIMITS, stated plainly: certificate lifetime is an imperfect proxy for automation — a long-lived certificate does not prove an inability to rotate, and a short one does not prove broad agility beyond TLS. Protocol currency (running TLS 1.3) indicates willingness to adopt new transport crypto but says nothing about application-layer or key-management agility. These signals correlate with, but do not measure, true crypto-agility. A future version intends to incorporate signed rotation attestations.", "signals": [ { "key": "rotation_cadence_proxy", "label": "Certificate rotation cadence (proxy)", "max": 55, "params": { "full_days": 100, "partial_days": 398, "partial_fraction": 0.5 }, "description": "Full points for a certificate lifetime \u003c= 100 days (consistent with automated ACME issuance/rotation); half for \u003c= 398 days; zero for longer (manual rotation likely). Proxy signal — see dimension limits." }, { "key": "protocol_currency_proxy", "label": "Protocol currency (proxy)", "max": 45, "params": { "tls12_fraction": 0.4 }, "description": "Full points for TLS 1.3; 40% for TLS 1.2 top; zero otherwise. Proxy for willingness to adopt current transport cryptography." } ] }, { "key": "certificate_lifecycle", "label": "Certificate Lifecycle", "weight": 15, "measurement": "direct", "description": "Directly measured certificate health: is the presented chain trusted and unexpired, is it comfortably within its renewal window, and is its lifetime within modern compliance limits?", "signals": [ { "key": "valid_not_expired", "label": "Trusted, unexpired chain", "max": 40, "description": "Full points when the leaf chain verifies against the system trust store and is not expired at observation time." }, { "key": "renewal_health", "label": "Healthy renewal window", "max": 35, "params": { "healthy_days": 21, "warning_days": 7, "warning_fraction": 0.5 }, "description": "Full points with \u003e= 21 days remaining; half with \u003e= 7; zero when expiring within a week or already expired. Days-remaining is resolved at observation time and stored, so scoring stays reproducible." }, { "key": "lifetime_compliance", "label": "Lifetime within limits", "max": 25, "params": { "max_days": 398 }, "description": "Full points for a certificate lifetime \u003c= 398 days (the current CA/Browser Forum maximum)." } ] }, { "key": "dependency_risk", "label": "Dependency Risk", "weight": 15, "measurement": "declared_proxy", "description": "DECLARED PROXY (v0.1). True dependency/supply-chain risk (JavaScript subresources, third-party origins, DNS/CDN provider concentration) is NOT inspected at v0.1 — we perform TLS handshakes only. v0.1 approximates operational maturity from two transport-layer signals: HSTS posture and certificate-authority reputation. LIMITS, stated plainly: a reputable CA and an HSTS header indicate a maintained deployment but say nothing about the breadth of an org's software supply chain or its provider concentration. Treat this dimension as a coarse maturity proxy, not a supply-chain audit. A future version intends to add subresource and DNS/provider analysis.", "signals": [ { "key": "hsts_posture", "label": "HSTS posture (proxy)", "max": 50, "params": { "strong_max_age": 15552000, "weak_fraction": 0.5 }, "description": "Full points for HSTS with max-age \u003e= 180 days; half for a present-but-short HSTS; zero when absent. Proxy for downgrade-resistance discipline." }, { "key": "ca_reputation", "label": "CA reputation (proxy)", "max": 50, "params": { "reputable_orgs": [ "Let's Encrypt", "DigiCert", "Sectigo", "GlobalSign", "Google Trust Services", "Amazon", "Entrust", "Microsoft", "GoDaddy", "IdenTrust", "Cloudflare", "SSL.com", "Actalis", "Buypass", "ZeroSSL" ], "unknown_fraction": 0.5 }, "description": "Full points when the issuing CA organisation is in the published reputable set; half for any other publicly-trusted issuer; zero when untrusted. Proxy for issuance-chain risk." } ] } ] }