Transparent Data Encryption for Azure SQL Database brings the trusted encryption technology found in SQL Server to the latest version of Azure SQL Database (V12). It encrypts your database at rest to help further protect against the threat of malicious activity. Transparent Data Encryption performs real-time encryption and decryption of your database, associated backups, and transaction log files.
For more information, please visit the Transparent Data Encryption documentation
page. There is no additional charge for this feature.