Temporal leakage

Privacy

Publishing a sequence of snapshots over time for the same fine-grained cell (even if each snapshot independently meets k-anonymity) can let an observer intersect the snapshots to re-identify an individual whose presence changed between them.

Detection

Compare successive published snapshots for the same cell; check whether the intersection of 'present in snapshot A and B' sets drops below the k-anonymity threshold.

Mitigation

  • Apply k-anonymity to the full published time series, not each snapshot independently
  • Add temporal noise or coarsen the time grain when publishing repeated cuts of the same fine cell

Affected conversions

  • PointH3
  • RasterH3