Imagine this: You have sensitive information in your database (ex: SSN or Employee Payroll Information). You perform weekly full database backups, daily diffs and hourly T-log backups. You ship out one copy of the database backup to an offsite location. At this point the backup copy of the database is not in your control as it has already left your office. It is very possible for someone to restore the copy of the database since Microsoft supports restoring the database on any SQL Server with the right version in which the backup was performed. However, you would still feel uncomfortable knowing that your database has sensitive information and that it is possible for someone to get their hands on to the backup copy of the database. What would you do?
SQL Server 2014 Now Supports Encrypted Backups.