Abstract:

In cloud computing environment, searchable encryption lets cloud server searching on users' encrypted data directly, without leaking the information of user data and searching criteria. Existing searchable symmetric encryption schemes believe that the access pattern and search pattern will be leaked inevitably, as long as no other information is leaked, the scheme will be secure. But recent research show that the acess pattern and search pattern can leak information about the user data and searching criteria under certain circumstance. In this paper, a new symmetric searchable encryption scheme which can hide search pattern is proposed. The scheme groups each distinct word appeared in user documents, lets the words with same searching results be in the same group, and constructs same trapdoors for the words in the same group, preventing the adversaries from distinguishing. The experiments show that the search pattern of at least one half of the words can be hidden. The proportion of search pattern hidden words will be increase as the size of the documents increasing, and the extra client side storage won’t grow dramatically. Finally, a basic idea to hide search pattern of the words which have different search results is provided.

Key words: searchable encryption, search pattern, information hiding