Relational database encryption works by making the data stored in a database unreadable to unauthorized users while still allowing authorized applications or users to access it. The process typically involves converting the plaintext data into encrypted data using algorithms and encryption keys. For example, when storing sensitive user information like credit card numbers, this data is encrypted before it is saved in the database. When an application needs to retrieve this data, it decrypts the information using the appropriate key, allowing it to return the original plaintext to an authorized user or application.
There are generally two types of encryption used in databases: encryption at rest and encryption in transit. Encryption at rest protects data stored on disk from unauthorized access, even if someone gains physical access to the storage system. This can be achieved using techniques like Transparent Data Encryption (TDE), which encrypts the entire database at the file level. On the other hand, encryption in transit protects the data as it travels over the network, ensuring that sensitive information, like login credentials, cannot be intercepted. Secure protocols such as TLS (Transport Layer Security) are typically used for this purpose, adding a layer of security for data being sent between client applications and the database server.
Implementing encryption in relational databases also involves key management. Proper handling of encryption keys is critical since they must be kept secure but accessible to authorized applications. Many databases offer built-in key management solutions, allowing developers to create, rotate, and manage keys without exposing them in application code. For example, systems like AWS KMS (Key Management Service) can integrate with database services to manage encryption keys securely. By employing these strategies, developers can ensure that sensitive information remains protected from potential breaches while maintaining its accessibility for legitimate use.