Why encryption is required in sql server 2008

From this point on, the entire user database, and tempdb database will be encrypted, although your applications will never know the difference. If you got lost with all the keys and certificates required to implement TDE, you are not alone. It is a complex topic and beyond the scope of this chapter. The focus of this chapter was to provide you an overview of what TDE is, how it works, and how to implement it. Because of the complexity involved in using TDE, you should only implement this technology when you full understand its many complexities and after thorough testing in a test environment.

Fortnightly newsletters help sharpen your skills and keep you ahead, with articles, ebooks and opinion to keep you informed. Brad M. View all articles by Brad McGehee. Federal Healthcare Managed Service Providers. Encryption occurs in real-time as data is written from memory to disk, and decryption occurs when data is read from disk and moved into memory.

Encryption is done at the database level, so you can choose to encrypt as few or as many databases as you want. In addition, initial setup and key management is simple and requires little ongoing maintenance.

TDE is not granular. Then entire database in encrypted. TDE does not protect communications between client applications and SQL Server, so other encryption methods must be used to protect data flowing over the network. When any one database on a SQL Server instance has TDE turned on, then the tempdb database is automatically encrypted, which can contribute to poor performance for both encrypted and non-encrypted databases running on the same instance. Although fewer resources are required to implement TDE than column-level encryption, it still incurs some overhead, which may prevent it from being used on SQL Servers that are experiencing CPU bottlenecks.

If you want to take advantage of both backup compression and encryption, you will have to use a third-party application, such as SQL Backup, which allows you to perform both of these tasks without penalty. They include: Create a Master Key : A master key is first created. It is really a simple process for implementing TDE. Cell Level Encryption requires a couple extra steps to modify your SQL code, but the basic architecture is pretty simple.

Contact us Blog Documentation. Townsend Security Data Privacy Blog. Now that we know what EKM is, how does it work? Transparent data encryption is really the solution for making sure that someone can't read the data from outside of SQL Server.

In other words the data in the database files is encrypted and if you can access the file you can't read the data because you don't know how to decrypt it. The transparent part is that SQL Server automatically encrypts and decrypts the data for users who have permission to access it.

The security model begins with logins that are given certain roles and access to databases, tables, stored procedures, etc. So how do you allow only certain users to read the databases data, even excluding syadmins? Great write up. Does the certificates need to be renewed or does it ever exipire? Just a small correction. Where it says "I use the private to encrypt data and someone else must use the public key to decrypt the data", actually it's the other way around.

You or anyone encrypt with the public key, and the owner of the private key decrypts with the private key. Related Articles. Decrypting SQL Server database objects. Asymmetric Keys. How much overhead does encryption add to a SQL Server query.

Storing passwords in a secure way in a SQL Server database. Popular Articles. Rolling up multiple rows into a single row and column for SQL Server data. How to tell what SQL Server versions you are running. Resolving could not open a connection to SQL Server errors. Ways to compare and find differences for SQL Server tables and data.

Searching and finding a string value in all columns in a SQL Server table. View all my tips. Back To Top This allows for full range and equality scans. Also, because the initial encryption scan spawns a new thread, performance is most sharply impacted at this time; expect to see queries perform several orders of magnitude worse. For disk space concerns, TDE does not pad database files on disk although it does pad transaction logs as previously noted in How Data is Encrypted.

TDE is not a form of access control. All users who have permission to access the database are still allowed access; they do not need to be given permission to use the DEK or a password.

Databases used in other editions cannot be encrypted by using TDE and TDE-encrypted databases cannot be used in other editions the server will error out on attempts to attach or restore. Thus, special care must be taken to ensure that the certificate that was used to protect the DEK see How to Enable TDE is backed up and maintained with the database backup.

If this certificate or certificates is lost, the data will be unreadable. Back up the certificate along with the database. Each certificate backup should have two files; both of these files should be archived ideally separately from the database backup file for security. Other Features that Write to Disk If a feature writes to disk through the buffer pool, data is protected.

Features that write directly to files outside of the buffer pool must manually manage encryption and decryption. Cell-level encryption is implemented as a series of built-ins and a key management hierarchy.

Using this encryption is a manual process that requires a re-architecture of the application to call the encryption and decryption functions. In addition, the schema must be modified to store the data as varbinary and then re-cast back to the appropriate data type when read. The traditional limitations of encryption are inherent in this method as none of the automatic query optimization techniques can be used.

Comparison with TDE Cell-level encryption has a number of advantages over database-level encryption. It offers a more granular level of encryption. In addition, data is not decrypted until it is used when a decryption built-in is called so that even if a page is loaded into memory, sensitive data is not in clear text.

Cell-level encryption also allows for explicit key management. Keys can be assigned to users and protected by passwords to prevent automatic decryption. This offers another degree of control users can, for example, have individual keys for their own data ; however, the administrator is further burdened with maintaining the keys although Extensible Key Management, described later in this paper, can also be used for easier administration.

Because cell-level encryption is highly configurable, it may be a good fit for applications that have targeted security requirements. The primary disadvantages of cell-level encryption are the application changes needed to use it, the performance penalties, and the administration cost.

As noted previously, encryption and decryption requires that you use built-ins. This is an entirely manual process and requires the varbinary data type; this means columns must be changed from their original data type to varbinary. For security, the encryption is always salted so the same data will have a different value after encryption. As a result, referential constraints such as foreign keys, and candidate keys such as primary keys do not provide any benefit on these encrypted columns. This also affects query optimization-indexes on the encrypted columns offer no advantage so range and equality searches turn into full table scans.

TDE allows full use of indexes and other traditional query optimization tools as well as performing the encryption in bulk. This inversely scales with workload size resulting in performance degradations that are several magnitudes worse when attempting to encrypt an entire database. One sample application with 10, rows was four times worse with one column encrypted, and 20 times worse with nine columns encrypted.

Because cell-level encryption is custom to each application, performance degradation will vary depending on application and workload specifics. Although these performance concerns for cell-level encryption can be mitigated by explicit application design, more care must be exercised to prevent the accidental leakage of data.

For example, consider a quick scheme to enable fast equality searches by using hashes of the sensitive data. If these hashes are stored in a column along with the encrypted data, it quickly becomes obvious if two rows have identical values because the hashes will be the same. Extra security reviews must be used to ensure that unintended data disclosures do not occur so both the database and application must be security aware. TDE prevents these data leak scenarios by encrypting at the broadest scope.

In both cell-level encryption and database-level encryption, information is decrypted on the server; decrypted data is sent to clients in plaintext. SSL is recommended to protect this channel. Recommended Usage with TDE Cell-level encryption can be used for defense in depth both for a database encrypted by TDE and for limited access control through the use of passwords.

That way, even if either TDE or authorization is subverted, data might still be safe if it is encrypted at the root by a password so that it cannot be as easily accessed. While all the disadvantages of using cell-level encryption apply, using both cell-level encryption and TDE may be useful for a subset of highly sensitive data.

In general, TDE and cell-level encryption accomplish two different objectives. If the amount of data that must be encrypted is very small or if the application can be custom designed to use it or if the application has custom design requirements and performance is not a concern, cell-level encryption is recommended over TDE. Otherwise, TDE is recommended for encrypting existing applications or for performance sensitive applications. It enables parts of the cryptographic key hierarchy to be managed by an external source such as Hardware Security Module HSM , referred to as a cryptographic provider.

Encryption and decryption operations using these keys are handled by the cryptographic provider. This allows for flexibility and choice in cryptographic providers as well as common key management.

No other form of asymmetric key is supported by TDE and database certificates cannot currently be provisioned through EKM. EKM is supported for cell-level encryption through symmetric and asymmetric keys. It is highly recommended that you use EKM with both database- and cell-level encryption for more comprehensive key management and hardware-based cryptography if available through the HSM.

Windows File Encryption Depending on which version of Windows is installed, Windows offers two granularities of file protection.