Q-Day readiness methodology

Discovery scope

The scanner discovers TLS certificates, JWKS signing keys, SSH host keys, email STARTTLS, and uploaded PEM/CSV bundles. Live scans probe port 443 (and scenario-defined ports); unreachable endpoints are recorded in scan coverage, not as false-positive assets.

Classification (Shor / Grover)

Each asset is mapped to a quantum vulnerability status: broken, at-risk (Shor-vulnerable RSA/ECC), safe (symmetric or PQC-ready), or unknown. Shor logical-qubit estimates are order-of-magnitude references only.

Mosca inequality

X (data shelf-life) + Y (migration time) versus Z (years to cryptographically relevant quantum computing). When X + Y > Z, harvest-now-decrypt-later risk is elevated for long-lived ciphertext.

Readiness score formula

Composite 0–100 score from quantum-vulnerable asset share, HNDL exposure, PQC-ready endpoint credit, and remediation coverage. Bands: Critical / At Risk / Developing / Prepared.

Coverage confidence

Heuristic 0–95% based on classified asset count (40% base + 4% per asset, capped at 95%). This is not a guarantee — shadow APIs, HSMs, and offline keys may be missed.

Glossary

• Readiness score — 0–100 composite score reflecting quantum-vulnerable asset share, HNDL exposure, PQC-ready endpoints, and remediation coverage. Higher is better. Reference
• Readiness band — Qualitative tier (Critical / At Risk / Developing / Prepared) derived from the readiness score for executive reporting. Reference
• Coverage confidence — Heuristic 0–95% estimate of scan completeness based on classified asset count. Not a guarantee — shadow keys and offline HSMs may be missed.
• Mosca inequality (X + Y > Z) — Dr. Michele Mosca's harvest-now-decrypt-later test: data shelf-life (X) plus migration time (Y) versus years to cryptographically relevant quantum computing (Z). When X + Y > Z, intercepted ciphertext may be decrypted before you finish migrating. Reference
• HNDL (Harvest Now, Decrypt Later) — Adversaries record encrypted traffic today and decrypt it once a cryptographically relevant quantum computer exists. Long-lived secrets and archived ciphertext are most exposed. Reference
• Already too late — Asset flagged when Mosca inequality holds for its data class — migration may not protect previously intercepted ciphertext.
• HNDL exposed — Asset flagged when Mosca inequality holds for its data class — migration may not protect previously intercepted ciphertext.
• CRQC (Cryptographically Relevant Quantum Computer) — A quantum computer capable of breaking widely deployed public-key cryptography such as RSA and elliptic-curve algorithms at scale. Reference
• Ciphertext — Encrypted data — readable only with the correct key. HNDL adversaries store ciphertext today to decrypt later when quantum computers break the wrapping public-key layer.
• Forward secrecy — Property of TLS 1.3 where session keys are ephemeral — passive capture of application data alone is insufficient without the handshake record.
• Key encapsulation (KEM) — Mechanism for securely exchanging symmetric keys. ML-KEM (FIPS 203) is the NIST-standardized post-quantum key encapsulation algorithm. Reference
• ECDH (Elliptic Curve Diffie-Hellman) — Key exchange using elliptic curves — quantum-vulnerable via Shor's algorithm. Used in most modern TLS handshakes.
• STARTTLS — Email encryption upgrade from plaintext to TLS in transit. Often uses RSA or ECDH — inventory email paths alongside web TLS.
• ML-KEM — NIST FIPS 203 module-lattice key encapsulation — the standardized post-quantum replacement for RSA/ECDH key exchange in hybrid TLS. Reference
• Shor logical qubits — Order-of-magnitude estimate of logical qubits required to break this key size via Shor's algorithm. Estimates only — not a Q-Day prediction. Reference
• Severity — Business impact tier (critical / high / medium / low / info) based on algorithm, exposure, and asset kind.
• Quantum status — Classification: broken (deprecated now), at-risk (Shor-vulnerable), safe (symmetric / PQC-ready), or unknown. Reference
• PQC ready — Endpoint negotiates hybrid post-quantum key exchange (e.g. X25519MLKEM768) or uses NIST-approved PQC algorithms. Reference
• Remediation coverage — Percentage of identified gaps with an assigned remediation action and tracked status.
• Crypto-agility score — Distinct from readiness: measures how quickly keys and algorithms can be rotated without service disruption. Reference
• CBOM (Cryptographic Bill of Materials) — Machine-readable inventory of cryptographic assets, algorithms, and key lineage — used to track PQC migration coverage across hosts, code, and HSMs. Reference

Rate limits & abuse prevention

Public assess-signup and mini-assessment endpoints are rate-limited per email domain. Live scans honor QTANGL_PQC_MAX_ENDPOINTS and QTANGL_PQC_SCAN_TIMEOUT server caps. See rate limits documentation.

Enterprise integrations

Scan-complete webhooks (v2) notify your SIEM or ticketing system when production scans finish. Slack drift alerts connect via dashboard Integration settings. Cloud inventory uploads support ACM export format first.

Drift monitoring guide · CI/CD integration

Limitations

• Endpoint-scoped inventory aid — not a formal cryptographic audit or penetration test.
• RSA/ECC remain classically secure until cryptographically relevant QC exists.
• Fixture replays use curated data; live scans reflect point-in-time negotiation.