Always Encrypted is a security feature introduced by Microsoft in SQL Server 2016, designed to protect sensitive data by ensuring it remains encrypted both at rest and in transit. This functionality is extended to Azure SQL Database and Azure SQL Managed Instance, providing a robust mechanism to safeguard confidential information from unauthorized access, including database administrators and cloud service providers.

To address limitations in processing encrypted data, Microsoft introduced Always Encrypted with secure enclaves. A secure enclave is a protected region of memory within the SQL Server process that allows computations on plaintext data inside the enclave, while keeping it encrypted outside. This enhancement enables operations such as pattern matching and range comparisons on encrypted data without exposing it to unauthorized users.

A healthcare provider implemented Always Encrypted to protect patient records, ensuring that sensitive information like social security numbers and medical histories remained confidential. By encrypting specific columns containing personal data, the organization-maintained compliance with regulations such as HIPAA, while allowing authorized applications to perform necessary operations on the data.

A financial institution adopted Always Encrypted to secure credit card information and transaction details. By utilizing deterministic encryption for columns involved in frequent queries and randomized encryption for highly sensitive data, the bank achieved a balance between security and functionality, reducing the risk of data breaches and unauthorized access.