HNDL
Harvest-Now-Decrypt-Later Exposure: Why Algorithm Counts Are Not Enough
Understand HNDL exposure, Mosca X+Y>Z, data lifetime, harvestability, attack paths, and why post-quantum risk needs more than flat crypto inventory.
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HNDL is a data-risk problem
Harvest-now-decrypt-later risk exists when sensitive data can be captured today and still matter when a future cryptographically relevant quantum computer exists. That means the risk depends on data lifetime, harvestability, attacker reachability, and the time horizon for migration.
Use Mosca X+Y>Z to prioritize
Mosca framing helps teams reason about whether the data confidentiality lifetime plus migration time exceeds the time until quantum capability.
- X: how long the data must remain confidential
- Y: how long migration and remediation will take
- Z: estimated time until the relevant quantum threat is practical
- Exposure window: the dated risk window created when X+Y exceeds Z