BE - Database Management Systems

Data encryption is a security technique used to protect sensitive information stored in a database by converting plain text (readable data) into ciphertext (unreadable, encoded data) using an algorithm and an encryption key. This ensures that even if unauthorized users gain access to the database files, they cannot decipher the data without the proper key.

Encryption can be applied to data in two primary states: data at rest and data in transit. Encryption of data at rest, such as that provided by Transparent Data Encryption (TDE), secures the physical database files on storage devices. For more granular protection, specific sensitive columns, like credit card numbers or social security numbers, can be encrypted individually. Encryption of data in transit, using protocols like SSL/TLS, secures information as it travels between the database server and client applications, preventing eavesdropping.

While essential for meeting regulatory compliance and mitigating the impact of data breaches, encryption introduces challenges. It can add performance overhead due to the processing required for encryption and decryption operations, and it necessitates a robust and secure key management system, as losing the encryption keys results in permanent data loss. Despite these complexities, encryption remains a critical last line of defense in a comprehensive database security strategy.