Efficient Fuzzy Search on Encrypted Data

We study the problem of efficient (sub-linear) fuzzy search on encrypted outsourced data, inthe symmetric-key setting. In particular, a user who stores encrypted data on a remote untrustedserver forms queries that enable the server to efficiently locate the records containing the requestedkeywords, even though the user may misspell keywords or provide noisy data in the query. Wedefine an appropriate primitive for a general closeness function on the message space that we callefficiently fuzzy-searchable encryption (EFSE ). Next we identify an optimal security notion forEFSE. We demonstrate that existing schemes do not meet our security definition and propose anew scheme that we prove secure under basic assumptions. Unfortunately, the scheme requireslarge ciphertext length, but we show that, in a sense, this space-inefficiency is unavoidable for ageneral, optimally-secure scheme. Seeking the right balance between efficiency and security, wethen show how to construct schemes that are more efficient and satisfy a weaker security notionthat we propose. To illustrate, we present and analyze a more space-efficient scheme for supportingfuzzy search on biometric data that achieves the weaker notion.