The interactive calculator needs JavaScript. The formula, an explanation and a worked example are below, so you can do the calculation by hand.
Your inputs
Your result
- Migration (classical key exchange still in use)
- Data must stay confidential
- Exposure window: readable but still sensitive
- CRQC planning year
- EU roadmap milestones
What to do next
- Inventory your key exchange first.HNDL only concerns data protected by quantum-vulnerable key exchange or public-key encryption (RSA, ECDH, Diffie-Hellman), mostly in TLS, VPNs and messaging. Find where it is used before anything else. A 2-minute readiness assessment shows where you stand.
- Prioritise long-lived data.Rank systems by the confidentiality lifetime of the data they carry, not by how many there are. The systems with the largest X are your first wave. Our HNDL guide explains the method.
- Plan hybrid ML-KEM.Hybrid key exchange (classical plus ML-KEM, FIPS 203) protects new traffic against harvesting without giving up today’s assurances. Check which of your libraries, load balancers and vendors already support it.
Want real numbers instead of estimates? In a free demo we run CRYPTAGION on a public repository that matches your stack and show where quantum-vulnerable key exchange actually is; a Pilot or Discovery then covers your own code, inside your perimeter.
Book a demo →How the calculation works
The calculator applies the inequality Michele Mosca proposed for deciding when to worry about quantum computers:
X + Y > Z → data protected today with classical key exchange is exposed.- X: how many years the data must stay confidential.
- Y: how many years it takes to move the system to post-quantum key exchange (plus any wait before you start).
- Z: how many years until a CRQC exists, here entered as a planning year: Z = planning year − current year.
Until the migration ends, an attacker can record traffic that uses classical key exchange. The last data recorded before the switch must stay secret for X more years. If that period ends after the CRQC year, there is a window in which the data is readable but still sensitive. Its length is the exposure:
exposure = X + Y − (Z − current year)Positive: exposed. Between −1 and 0 (less than 2 years of margin): at the edge. −2 or below: within margin.
Worked example
Assume the current year is 2026, customer contracts that must stay confidential for 10 years, a 5-year migration and the 2032 planning scenario.
| X + Y | 10 + 5 = 15 years |
|---|---|
| Z | 2032 − 2026 = 6 years |
| Exposure | 15 − 6 = 9 years: exposed |
| In calendar years | Migration ends in 2031. Data recorded until then must stay secret until 2041, but could be readable from 2032. A contract sent today must stay secret until 2036, yet could be readable from 2032. |
With a 2-year confidentiality need and a 3-year migration, the same scenario gives 2 + 3 − 6 = −1: at the edge, with one year of margin.
Source: M. Mosca, “Cybersecurity in an Era with Quantum Computers: Will We Be Ready?”, IEEE Security & Privacy, vol. 16, no. 5, pp. 38–41, 2018, doi:10.1109/MSP.2018.3761723. Preprint: IACR ePrint 2015/1075.