Anna Hoffman continues a series on reviewing important academic papers in SQL Server’s history:
Encryption at rest solves one threat. It stops someone who walks off with the disk. It does nothing about someone with administrative access to the running server, because the database decrypts data into memory to do anything useful with it.
For a lot of workloads that gap doesn’t matter. For health records, financial data, or anything where the customer’s threat model includes the cloud operator, it matters a great deal.
Azure SQL Database Always Encrypted (SIGMOD 2020) describes how SQL Server runs real queries, including range comparisons and LIKE patterns, against data it never holds the keys to.
Read on for Anna’s thoughts about the paper, its claims at the time, and how Always Encrypted has changed (for the better) since the original paper.