String Sanitization Under Edit Distance: Improved and Generalized
Abstract
Let W be a string of length n over an alphabet Σ, k be a positive integer, and S be a set of length-k substrings of W. The ETFS problem asks us to construct a string X ED such that: (i) no string of S occurs in X ED ; (ii) the order of all other length-k substrings over Σ is the same in W and in X ED ; and (iii) X ED has minimal edit distance to W. When W represents an individual's data and S represents a set of confidential patterns, the ETFS problem asks for transforming W to preserve its privacy and its utility [Bernardini et al., ECML PKDD 2019]. ETFS can be solved in O(n 2 k) time [Bernardini et al., CPM 2020]. The same paper shows that ETFS cannot be solved in O(n 2−δ) time, for any δ > 0, unless the Strong Exponential Time Hypothesis (SETH) is false. Our main results can be summarized as follows: • An O(n 2 log 2 k)-time algorithm to solve ETFS. • An O(n 2 log 2 n)-time algorithm to solve AETFS, a generalization of ETFS in which the elements of S can have arbitrary lengths.
Domains
Computer Science [cs]
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