This is the First part of the Series Which Covers how to handle the Encryption piece in SQL Server. The Term “Encryption” is one of the Most Interesting and annoying things which we as DBA’s see, especially if we never dealt with Database Encryption,Certificates, Keys in the Past and all of a sudden we got a request from the Application team saying “Hey My Dear DBA! Our Database for this Application is going to contain PII(Personally Identifiable Information) Such as SSN, Address etc and should be SOX (Sarbanes-Oxley Act) Complaint, and we need the Data to be Encrypted. What are the Options we’ve in SQL Server?…” So what are the Options we really have in SQL Server?
Well, In this part of the Encryption Series let’s try to explore what are the Options we’ve to Encrypt Data from Windows Server Perspective. In the future Posts I’ll be showing you what are the options from SQL Server stand point. For now..Let’s look at basic Windows Encryption techniques.
Encrypting File System(EFS):
EFS basically is at File(s)/Folder(s) Level. It Encrypts the Files or Folder(s) based on the User accounts. It doesn’t Encrypt all the contents of the Drive independent of any user. let’s say…you’ve multiple User accounts or groups, they can individually encrypt their own Files and Folders Independently. You need not be even an Administrator on the Server to implement EFS and encrypt your Files!! No Special Softwares, no special Hardware pieces required to be attached to your motherboard! It’s pretty Basic level of encryption, in which all your encryption keys are stored in your OS Drive(typically C$). So, what if hacker is too smart and got into your C$?? yes, He/she can decrypt all your encrypted stuff in no time!!
Bitlocker is at Drive/Volume level. It encrypts all the contents(files/folders) on all the Drives Including System Files in Operating System Drive and Removable Drive(s) as well! It’s independent on User accounts. The Contents will be encrypted irrespective of the User account(s). i.e, Once Bitlocker Encryption is turned ON, all the Files/Folders will be Encrypted for all the Users. You have to be a a member of Local Admins Group at minimum to turn on Bitlocker Encryption and it requires a special hardware piece called Trusted Platform Module(TPM) to encrypt the contents at Drive level. Since the OS Drive itself is encrypted, for a hacker even if he/she got hold of C$, they really can’t get into Encryption Keys.(So..It’s quite possible, we can use EFS to let Users to encrypt individual Files and Windows Server Admin Encrypts the OS Drive using Bitlocker. Few Companies use this Technique as their Security practice)
As per the Microsoft Documentation – Enabling EFS for SQL Server Database Files is not a good idea and they both together doesn’t work well in terms of performance. They’ve(EFS and TDE – Transparent Data Encryption, this is something which we enable at SQL Database level which I’ll be exploring in future posts) concurrency Issues working together! Bitlocker for SQL Server(Bitlocker and TDE) has no noticeable concurrency issues working together. If you reallyyyy…need that level of Encryption, Yes you can definitely think Bitlocker/TDE combination as an efficient solution.