We’re evaluating encryption strategies for our advanced planning module data and I’m curious about the trade-offs between application-level encryption and transparent database encryption (TDE). Our planning data includes demand forecasts, capacity models, and supplier information - some of which contains commercially sensitive data that requires encryption at rest for compliance.
Application-level encryption gives us fine-grained control over which fields get encrypted, but adds complexity to queries and indexing. TDE is transparent to the application but encrypts everything at the tablespace level, which might be overkill. We’re on SQL Server 2019 with Apriso 2021. What approaches have others taken for protecting planning data while maintaining query performance? Also interested in key management strategies - hardware security modules vs software-based key vaults.
Our main compliance drivers are GDPR for European operations and some customer contracts requiring encryption of commercially sensitive forecasts. We don’t have ITAR requirements. The hybrid approach sounds interesting - could you use TDE for the entire planning database, then add application-level encryption only for the most sensitive columns? Would that create double encryption overhead?
We went with TDE for our planning database and it’s been solid. The performance impact is minimal - maybe 3-5% CPU overhead on our SQL Server environment. The big advantage is that it’s completely transparent to Apriso, so no application code changes needed. We use Azure Key Vault for key management, which handles rotation automatically. For compliance audits, TDE makes it simple to prove data is encrypted at rest without complex application-level controls.
I’ve implemented both approaches at different sites. Application-level encryption is better if you need column-level control - for example, encrypting supplier pricing but not general planning parameters. The challenge is that encrypted columns can’t be indexed efficiently, so range queries on encrypted data become table scans. TDE avoids this but encrypts everything including non-sensitive lookup tables. Consider a hybrid approach: TDE for the base layer, then application-level encryption for the most sensitive fields.
Double encryption (TDE + application-level) does add overhead, but it’s not as bad as you’d think. TDE overhead is mostly on I/O operations, while application-level encryption hits CPU during data processing. If you go this route, make sure your application-level encryption uses hardware acceleration (AES-NI instructions on modern CPUs). We saw about 8% total overhead with both layers, which was acceptable for our use case. The real performance killer is encrypting columns used in WHERE clauses or JOINs.