A Symmetric Searchable Encryption Scheme with Forward and Backward Privacy Based on VBTree

When a large amount of data is stored in cloud servers, untrusted cloud servers may greatly lead to privacy leakage. Searchable encryption is an important technology to enable searching on the encrypted data structure without leaking the search keyword and the data. Recently, many studies focus on complex search such as conjunctive keyword on the dynamic dataset which supports insertion and deletion operation. Dynamic searchable encryption needs to support forward and backward privacy. VBTree (Wu et al., 2018) is a tree-based data structure which firstly supports conjunctive search on encrypted data structure and ensures forward privacy but lacks backward privacy. To protect the backward privacy of VBTree-based searchable encryption scheme, we further utilize a bloom filter and a Trusted Execution Environment (TEE) technology. Specifically, we use a bloom filter to record deleted data. In addition, Intel SGX will parse the trapdoor into single keywords during the search process and then check against the bloom filter to determine if the data has been deleted. This approach ensures that deleted data is excluded from the query results, thereby preventing the retrieval of deleted information and guaranteeing the backward privacy.