Configuring Always Encrypted with Secure Enclaves for Azure SQL Database
You are the database administrator for a healthcare organization that uses Azure SQL Database. You need to implement column-level encryption for a column containing patient Social Security numbers (SSNs). The SSNs must be encrypted at rest and in transit, and only authorized client applications should be able to decrypt them. Which technology should you use?
⚠ Common exam trap
Candidates often confuse Transparent Data Encryption (TDE) with column-level encryption, mistakenly thinking TDE protects data from all unauthorized access, when in fact TDE only encrypts data at rest and does not prevent authorized database users from reading sensitive columns in plaintext.
Answer choices
Why each option matters
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Always Encrypted with column master key stored in Azure Key Vault.
Always Encrypted is the correct choice because it ensures that sensitive data, such as SSNs, is encrypted both at rest and in transit, and the encryption keys are stored client-side (e.g., in Azure Key Vault). This design ensures that only authorized client applications with access to the column master key can decrypt the data, preventing even database administrators or cloud operators from viewing the plaintext values.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Row-level security (RLS) to restrict access based on user role.
Why it's wrong here
Row-level security filters which rows a user can access, but the SSN column stays unencrypted for permitted rows, so it fails the encryption requirement entirely. Always Encrypted is required. RLS is tempting because it restricts access by role, yet it governs row visibility, not column confidentiality.
- ✗
Dynamic data masking (DDM) to mask SSNs for unauthorized users.
Why it's wrong here
Dynamic data masking obscures SSNs in query results for unauthorised users, but the underlying column remains plaintext, so it provides no encryption at rest or in transit. Always Encrypted is required. DDM is tempting because it limits exposure to specific users, yet masking is a presentation-layer control, not cryptographic protection.
- ✗
Transparent Data Encryption (TDE) with customer-managed keys.
Why it's wrong here
TDE encrypts the entire database, including backups and log files, but decrypts transparently for any query, so it cannot restrict decryption to authorised client applications. Always Encrypted is required for column-level control. TDE is tempting because it satisfies encryption at rest with customer-managed keys, yet it offers no per-application decryption boundary.
- ✓
Always Encrypted with column master key stored in Azure Key Vault.
Why this is correct
Always Encrypted with the column master key in Azure Key Vault encrypts SSNs at rest and in transit, and only client applications with key access can decrypt them. Azure SQL Database never sees plaintext, satisfying the authorised-client constraint.
Go deeper
Related to this question
Learn chapter
Securing Data at Rest and in Transit
Key term
Azure SQL Performance Tuning
Azure SQL Performance Tuning is the process of optimizing the speed and efficiency of queries and database operations in Microsoft Azure SQL Database or SQL Managed Instance to reduce latency and improve throughput.
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Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
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