Introduction to Database Encryption

Encryption can provide strong security for data, but is that enough ? Data in a database can be accessed by many systems, but developing a database encryption strategy must take many factors into consideration. Where should the encryption be performed, for example — in the database, or in the application where the data originates? Who should have access to the encryption keys? How much data must be encrypted to provide security? What’s an acceptable trade-off between data security and application performance?
Data encryption is a process of converting stored or transmitted data to a coded form in order to prevent it from being read by unauthorized person. It is an application of a specific algorithm to alter the appearance of data, making it incomprehensible to those who are not authorized to see the information.
There are 2 types of encryption algorithm: -
- Secret key or Symmetric key algorithm: -In this encryption algorithm, a single secret or private key is shared between the sender and receiver. The sender encrypts this using this key and receiver decrypts it using the same key. It is highly assumed that no one else knows the key.
- Public key or Asymmetric key algorithm: - In this algorithm, every sender and receiver has a pair of keys. One is made public to the network and called public key and the other is kept private to that node called private key. The pair is such made that if the data is encrypted with one of the keys in the pair, it can only be decrypted with other key in the pair. When a sender has to send, it encrypts the data with receiver’s public key & the receiver decrypts it with its private key.

Advice on how to overcome some of the challenges in database encryption:
- Regulatory drivers : Advanced security through database encryption is required across many different sectors, and increasingly to comply with regulatory mandates.
One approach that can help companies address the encryption challenges associated with regulation is the defense-in-depth principle which advocates many layers to strong security – ranging from physical security and access controls to rights assignment and network security, including firewalls and, crucially, encryption of both data at rest and in transit.
- Overcoming key management issues
It is important that database encryption be accompanied by key management; however, statistics show that this is also the main barrier to database encryption. It is well-recognized that key use should be restricted and that key backup is extremely important. An additional best practice rule of encryption is that the encrypted key should never be stored alongside the data it was used to encrypt. Placing encryption keys within the HSM enforces this policy.
- Separation of duties and dual control
Many organizations pay close attention to separation of duties and dual control, which is required to pass audits to show that there are internal controls protecting against rogue administrators or unauthorized employees and is often required by the various regulatory requirements discussed above.