—Database security has become a vital issue in modern Web applications. Critical business data in databases is an evident target for attack. Therefore, ensuring the confidentiality, privacy and integrity of data is a major issue for the security of database systems. Recent high profile data thefts have shown that perimeter defenses are insufficient to secure sensitive data. Encryption is a well established technology for protecting sensitive data, but developing a database encryption strategy must take many factors into consideration. In the case of semitrusted databases where the database contents are shared between many parties, using server-based encryption (server encrypts all data) or client-based encryption (client encrypts all data) is not sufficient to protect semi-trusted databases. This paper presents a practical implementation of field level encryption in the semi-trusted database system by encrypting database content in a mixed form. Our solution is called Mixed Cryptogra...