Searchable Encryption Scheme on the Cloud via Fully Homomorphic Encryption

We constructed a new secure searchable encryption scheme aided by a computationally powerful but untrusted cloud server. Our scheme allows a client to provide a single search token to the server, but still allows the server to search for that token's word over all the documents he can access that encrypted with different keys. We achieved the scheme using multikey fully homomorphic encryption (MFHE) which is capable of operating on inputs encrypted under multiple, unrelated keys. Based on this, we extended the scheme to multiple keyword searching.