An Unlinkable Secret Handshake with Fuzzy Matching for Social Networks

An unlinkable secret handshake allows two members from the same groups to secretly distinguish each other. In this paper, a new unlinkable secret handshake scheme is constructed to achieve fuzzy matching. The proposed scheme supports more flexible threshold-based appropriate matching under the multiple-groups environment, which is not limited to authenticate between members from the same groups. Our new scheme is constructed from the fuzzy identity-based encryption scheme and constant-size group signature. Without using the random oracle, the new scheme is proved secure by assuming the intractability of the decisional bilinear Diffie-Hellman problems. Compared with previous works, our proposed scheme is adaptive to realize for many different applications.