Dynamic Searchable Symmetric Encryption With Strong Security and Robustness

Dynamic Searchable Symmetric Encryption (DSSE) is a prospective technique in the field of cloud storage for secure search over encrypted data. A DSSE client can issue
update
queries to an honest-but-curious server for adding or deleting his ciphertexts to or from the server and delegate keyword
search
over those ciphertexts to the server. Numerous investigations focus on achieving strong security, like forward-and-Type-I−-backward security, to reduce the information leakage of DSSE to the server as much as possible. However, the existing DSSE with such strong security cannot keep search correctness and stable security (or robustness, in short) if irrational queries are issued by the client, like duplicate
add
or
delete
queries and the
delete
queries for removing non-existed entries, to the server unintentionally. Hence, this work proposes two new DSSE schemes, named
$\mathtt {SR-DSSE}_{a}$
and
$\mathtt {SR-DSSE}_{b}$
, respectively. Both two schemes achieve forward-and-Type-I−-backward security while keeping robustness when irrational queries are issued. In terms of performance,
$\mathtt {SR-DSSE}_{a}$
has more efficient communication costs and roundtrips than
$\mathtt {SR-DSSE}_{b}$
. In contrast,
$\mathtt {SR-DSSE}_{b}$
has a more efficient search performance than
$\mathtt {SR-DSSE}_{a}$
. Its search performance is close to the existing DSSE scheme with the same security but fails to achieve robustness.