TY - GEN
T1 - Reverse-safe data structures for text indexing
AU - Bernardini, Giulia
AU - Chen, Huiping
AU - Fici, Gabriele
AU - Loukides, Grigorios
AU - Pissis, Solon P.
PY - 2020/1/1
Y1 - 2020/1/1
N2 - We introduce the notion of reverse-safe data structures. These are data structures that prevent the reconstruction of the data they encode (i.e., they cannot be easily reversed). A data structure D is called z-reverse-safe when there exist at least z datasets with the same set of answers as the ones stored by D. The main challenge is to ensure that D stores as many answers to useful queries as possible, is constructed efficiently, and has size close to the size of the original dataset it encodes. Given a text of length n and an integer z, we propose an algorithm which constructs a z-reverse-safe data structure that has size O(n) and answers pattern matching queries of length at most d optimally, where d is maximal for any such z-reverse-safe data structure. The construction algorithm takes O(nω log d) time, where ω is the matrix multiplication exponent. We show that, despite the nω factor, our engineered implementation takes only a few minutes to finish for million-letter texts. We further show that plugging our method in data analysis applications gives insignificant or no data utility loss. Finally, we show how our technique can be extended to support applications under a realistic adversary model.
AB - We introduce the notion of reverse-safe data structures. These are data structures that prevent the reconstruction of the data they encode (i.e., they cannot be easily reversed). A data structure D is called z-reverse-safe when there exist at least z datasets with the same set of answers as the ones stored by D. The main challenge is to ensure that D stores as many answers to useful queries as possible, is constructed efficiently, and has size close to the size of the original dataset it encodes. Given a text of length n and an integer z, we propose an algorithm which constructs a z-reverse-safe data structure that has size O(n) and answers pattern matching queries of length at most d optimally, where d is maximal for any such z-reverse-safe data structure. The construction algorithm takes O(nω log d) time, where ω is the matrix multiplication exponent. We show that, despite the nω factor, our engineered implementation takes only a few minutes to finish for million-letter texts. We further show that plugging our method in data analysis applications gives insignificant or no data utility loss. Finally, we show how our technique can be extended to support applications under a realistic adversary model.
UR - http://www.scopus.com/inward/record.url?scp=85079407215&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=85079407215&partnerID=8YFLogxK
U2 - 10.1137/1.9781611976007.16
DO - 10.1137/1.9781611976007.16
M3 - Conference contribution
AN - SCOPUS:85079407215
T3 - Proceedings of the Workshop on Algorithm Engineering and Experiments
SP - 199
EP - 213
BT - 2020 Proceedings of the Symposium on Algorithm Engineering and Experiments, ALENEX 2020
A2 - Blelloch, Guy
A2 - Finocchi, Irene
PB - Society for Industrial and Applied Mathematics Publications
T2 - 2020 Symposium on Algorithm Engineering and Experiments, ALENEX 2020
Y2 - 5 January 2020 through 6 January 2020
ER -