• DOI:10.1007/978-3-642-39256-6_13
• Corpus ID: 17940906

Optimal Re-encryption Strategy for Joins in Encrypted Databases

@inproceedings{Kerschbaum2013OptimalRS,
  title={Optimal Re-encryption Strategy for Joins in Encrypted Databases},
  author={Florian Kerschbaum and Martin H{\"a}rterich and Patrick Grofig and Mathias Kohler and Andreas Schaad and Axel Schr{\"o}pfer and Walter Tighzert},
  booktitle={DBSec},
  year={2013}
}

• F. Kerschbaum, Martin Härterich, +4 authors Walter Tighzert
• Published in DBSec 2013
• Computer Science, Mathematics

In order to perform a join in a deterministically, adjustably encrypted database one has to re-encrypt at least one column. The problem is to select that column that will result in the minimum number of re-encryptions even under an unknown schedule of joins. Naive strategies may perform too many or even infinitely many re-encryptions. We provide two strategies that allow for a much better performance. In particular the asymptotic behavior is O(n) resp. O(n log n) re-encryptions for n columns. We show that there can be no algorithm better than O(n log n). We further extend our result to element-wise re-encryptions and show experimentally that our algorithm results in the optimal cost in 41% of the cases.