Summary and Open Questions

• Very high perturbation is needed for privacy

  • Threshold phenomenon – above n: total privacy, below n: none (poly-time adversary)
  • Rules out many currently proposed solutions for SDB privacy
  • Q: what’s on the threshold? Usability?

• Main tool: A reconstruction algorithm

  • Reconstructing an n-bit string from perturbed partial sums/thresholds

• Privacy for a T-bounded adversary with a random database

  • T perturbation
  • Q: other database distributions

• Q: Crypto and SDB privacy?

Notes: