Education
Mosca inequality worked examples by industry
Mosca's inequality turns harvest-now-decrypt-later into arithmetic. These industry examples show when the risk window is already open.
The formula
X + Y > Z means exposure when:
- X = years data must remain confidential
- Y = years to complete cryptographic migration
- Z = years until a CRQC breaks your algorithms
Source: Global Risk Institute quantum threat timeline report. See also PostQuantum.com on HNDL.
Use the interactive Mosca calculator with your assumptions.
Worked examples
Healthcare payer (25-year retention)
| Variable | Value | Rationale |
|---|---|---|
| X | 25 | Member records, claims archives |
| Y | 7 | Multi-vendor TLS, legacy EDI, partner BAA scope |
| Z | 12 | Mid-range planning estimate |
| X + Y | 32 > 12 | Exposure now |
Regional bank (15-year transaction archives)
| Variable | Value | Rationale |
|---|---|---|
| X | 15 | Wire transfer and audit logs |
| Y | 5 | Core banking + vendor API dependencies |
| Z | 10 | Accelerated industry planning |
| X + Y | 20 > 10 | Exposure now |
SaaS vendor (3-year contract data)
| Variable | Value | Rationale |
|---|---|---|
| X | 3 | Typical customer agreement horizon |
| Y | 4 | Full stack + customer-managed keys |
| Z | 10 | Conservative CRQC estimate |
| X + Y | 7 < 10 | Lower HNDL urgency — still migrate early |
Even when inequality "passes," migration takes years — NIST recommends starting now.
This quarter
- Assign X per data class from legal retention schedules.
- Estimate Y honestly — include third-party dependencies.
- Document Z as a planning range, not a prediction (GQI summary).
Continue on the Q-Day hub: Mosca inequality guide
References & further reading
Authoritative primary sources cited in this article. Summaries are our own — follow links for full context.
Last verified 2026-06-21
- Quantum Threat Timeline Report (Mosca inequality)Global Risk Institute · 2023Dr. Michele Mosca's X + Y > Z framework for harvest-now-decrypt-later exposure planning.
- What Is Harvest Now, Decrypt Later (HNDL)?PostQuantum.com · 2024Mosca theorem, HNDL urgency, and why migration must start before Q-Day headlines.
- Q-Day: Accelerated Timeline Across Wider Attack SurfaceQuantum Computing Report · 2026-04Research summary on ECC-256 potentially breaking before RSA-2048 on accelerated timelines.
- What Is Post-Quantum Cryptography?NIST · 2024Official overview of NIST's PQC project, finalized standards, and the harvest-now-decrypt-later threat model.
- Michele Mosca: As We Enter a New Quantum EraPerimeter Institute (YouTube) · 2015Michele Mosca on quantum threats to cryptography, crypto-agility, and preparing cyber infrastructure.
See your exposure with evidence
Run a live PQC inventory scan, export a CBOM, and verify signed reports independently.
