Abstract
Recently, database users have begun to use cloud database services to outsource their databases. This is due to the high computation speed and the huge storage capacity the cloud owners provide at low prices. Despite cloud computing being an attractive environment for database users, privacy issues are cause for concern for database owners since the data access will be out of their control. Encryption is the only way of assuaging users' fears surrounding data privacy. However, executing Structured Query Language (SQL) queries over encrypted data is a challenging task, especially if the data are encrypted by a randomized encryption algorithm. Many researchers have addressed the privacy issues by using deterministic encryption, onion layers encryption, or homomorphic encryption to encrypt data. But, even with these systems, the encrypted data can still be subject to attack. In this research, we propose a model to execute SQL queries over encrypted data, where the data are encrypted by a single randomized encryption algorithm namely, Advanced Encryption Standard AES-CBC. We move most of the computations to the cloud and leave users with no crypto computation. Our model intends to narrow the range of retrieved encrypted records from the cloud to a small set of records that are candidates for the user's query. We implement and evaluate our model and find that it is both practical and efficient. Our experiments show that our model succeeds in minimizing the decryption processes to less than 30% of decryption the whole set of encrypted records in a table.