Data Encryption Plan Template for PMs

Encryption at rest protects data stored on disk (databases, files, backups). Encryption in transit protects data moving between systems (API calls, database connections, file transfers). You need both. A system that encrypts the database but sends queries over plaintext HTTP is only half-protected.

Use AES-256. The performance difference is negligible on modern hardware (less than 5% for most workloads), and AES-256 provides a significantly larger security margin. AES-128 is not broken, but there is no practical reason to choose it for new implementations when AES-256 is equally available.

Envelope encryption uses two layers of keys: a data encryption key (DEK) that encrypts the data, and a key encryption key (KEK) that encrypts the DEK. The DEK stays with the data (encrypted), and the KEK stays in KMS. This approach enables key rotation without re-encrypting all data (just re-encrypt the DEK with the new KEK) and supports per-record or per-tenant encryption keys without managing thousands of KMS keys.

Volume encryption (RDS, EBS) adds less than 5% overhead. Field-level application encryption adds 1-5ms per encrypt/decrypt operation depending on data size. TLS adds a one-time handshake cost (10-50ms) and negligible per-request overhead. For most SaaS products, encryption performance impact is unnoticeable. Profile before optimizing.

If development or staging environments contain copies of production data (even anonymized), yes. Many compliance frameworks (SOC 2, HIPAA) require encryption wherever sensitive data exists, regardless of environment. Use the same encryption approach as production, but with separate keys.