Research and application on the query processing for encrypted XML data

Based on the analysis of the existing Query-Aware Decryption Algorithm, an improved query processing algorithm for encrypted XML data is developed, which allows us to decrypt only those parts that would contribute to the query result. Our algorithm applies Hash tables and chained lists to create the indexes for user keys, and disseminates an encrypted XML index along with the encrypted XML data. As the decrypted index outputs where the query results are located in the encrypted XML data, the unnecessary decryption can be prevented for other parts of the data. The experimental results show that the method improves the performance of query processing, efficiently avoids decrypting non-relative data, subtly reduces the amount of user keys exchange and solves the dissemination of user keys.