International Association for Cryptologic Research

International Association
for Cryptologic Research


Paper: Fuzzy Private Matching (Extended Abstract)

Łukasz Chmielewski
Jaap-Henk Hoepman
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Abstract: In the private matching problem, a client and a server each hold a set of $n$ input elements. The client wants to privately compute the intersection of these two sets: he learns which elements he has in common with the server (and nothing more), while the server gains no information at all. In certain applications it would be useful to have a private matching protocol that reports a match even if two elements are only similar instead of equal. Such a private matching protocol is called \emph{fuzzy}, and is useful, for instance, when elements may be inaccurate or corrupted by errors. We consider the fuzzy private matching problem, in a semi-honest environment. Elements are similar if they match on $t$ out of $T$ attributes. First we show that the original solution proposed by Freedman et al. is incorrect. Subsequently we present two fuzzy private matching protocols. The first, simple, protocol has bit message complexity $O(n \binom{T}{t} (T \log{|D|}+k))$. The second, improved, protocol has a much better bit message complexity of $O(n T (\log{|D|}+k))$, but here the client incurs a $O(n)$ factor time complexity. Additionally, we present protocols based on the computation of the Hamming distance and on oblivious transfer, that have different, sometimes more efficient, performance characteristics.
  title={Fuzzy Private Matching (Extended Abstract)},
  booktitle={IACR Eprint archive},
  keywords={cryptographic protocols / fuzzy matching, secure 2-party computation, secret sharing},
  note={ 13812 received 12 Sep 2007, last revised 26 Oct 2007},
  author={Łukasz Chmielewski and Jaap-Henk Hoepman},