How We Survived Encryption: Lessons Learned

For most of our early engineering years, encryption was an afterthought—a checkbox we ticked with a default TLS config and a haphazardly implemented AES-256 library. That changed two years ago when a key rotation failure locked us out of 12% of our production user data, triggered a 48-hour outage, and nearly cost us a major enterprise contract. What followed was a year-long overhaul of our encryption strategy, full of hard-won lessons that we’re sharing here to help other teams avoid the same pitfalls.

The Breaking Point: When Encryption Became a Liability

Our outage stemmed from a fragmented key management setup: we had 14 separate encryption keys stored across hardcoded config files, environment variables, and a legacy on-premises HSM that only two retired engineers knew how to access. When we attempted a routine key rotation for our user data store, we accidentally rotated the decryption key for a subset of records without updating the key mapping in our application layer. The result? Thousands of user profiles, payment records, and session data became unreadable, and our support team was flooded with access complaints within 20 minutes of the rotation.

That incident forced us to confront a hard truth: our encryption strategy was designed for compliance, not resilience. We had prioritized "encrypt everything" over "encrypt smartly," and it nearly broke the company.

Lesson 1: Centralize Key Management Early

The first fix we implemented was a centralized Key Management Service (KMS) to replace our fragmented key storage. We migrated all encryption keys to HashiCorp Vault, with strict access controls, automated rotation policies, and audit logs for every key operation. This eliminated key sprawl, reduced the risk of human error in key handling, and gave us a single pane of glass for all encryption-related activity.

We also implemented envelope encryption for all data at rest: each data record is encrypted with a unique data key, which is itself encrypted with a master key stored in Vault. This means we never have to rotate data keys for individual records—only the master key, which is automated and low-risk. For teams just starting out, even a managed KMS like AWS KMS or Google Cloud KMS is better than ad-hoc key storage.

Lesson 2: Don’t Over-Encrypt (Yes, That’s a Thing)

Before the outage, we encrypted every piece of data we touched: public user bios, static configuration files, even cached API responses that were already behind a private VPC. This caused unnecessary performance overhead—our API latency increased by 18% due to decryption operations—and made debugging nearly impossible, since even non-sensitive logs were encrypted.

We adopted a data classification framework to fix this: we categorize data into three tiers: (1) Restricted (PII, payment info, health data) which requires full at-rest and in-transit encryption, (2) Internal (employee records, internal metrics) which requires in-transit encryption and optional at-rest encryption, and (3) Public (marketing content, public API docs) which requires no encryption beyond standard TLS. This reduced our encryption overhead by 40% and made our systems far easier to debug.

Lesson 3: Build Compliance Into Encryption Workflows

We used to treat compliance (GDPR, HIPAA, SOC 2) as a separate process from encryption—our security team would run quarterly audits to check if we were encrypting the right data, and we’d scramble to fix gaps before the audit deadline. This led to last-minute patches that introduced more bugs than they fixed.

Now, we bake compliance requirements into our encryption pipelines. For example, our data ingestion service automatically tags incoming data with its classification tier, then applies the correct encryption policy based on that tag. We also have automated checks that verify all restricted data is encrypted with approved algorithms (AES-256 for at-rest, TLS 1.3 for in-transit) and that key rotation schedules meet compliance requirements. This has reduced our audit prep time from 6 weeks to 3 days.

Lesson 4: Test Decryption as Rigorously as Encryption

Most teams test that their encryption works—they’ll encrypt a test string and verify it’s unreadable. But very few test that decryption works under failure conditions: what happens if a key is rotated mid-session? What if the KMS is unavailable? What if a key is accidentally deleted?

We added decryption testing to our chaos engineering suite: we regularly simulate key rotation failures, KMS outages, and corrupted key mappings in our staging environment to verify that our systems fail gracefully. We also run weekly decryption checks for all production data stores: automated jobs attempt to decrypt a random sample of records, and alert us if any fail. This has caught 3 potential decryption failures before they reached production.

Lesson 5: Invest in Cross-Team Encryption Literacy

Encryption used to be the sole domain of our security team—developers would call the security team whenever they needed to encrypt a new data field, and operations teams had no idea how key rotation worked. This created bottlenecks and meant that encryption decisions were often made without context for the systems they affected.

We launched a quarterly encryption training program for all engineering and product teams, covering basics like algorithm selection, key management best practices, and compliance requirements. We also created a self-serve encryption portal where developers can request encryption for new data fields, with automated policy checks to ensure they’re using the right encryption for the data tier. This reduced encryption-related support tickets by 70% and eliminated the security team bottleneck.

Conclusion

Surviving our encryption crisis required us to shift our mindset from "encryption as a compliance checkbox" to "encryption as a core system resilience practice." The lessons we learned weren’t just about tools or configurations—they were about process, cross-team collaboration, and prioritizing resilience over perfection. If your team is struggling with encryption, start with centralized key management, classify your data, and test your decryption. It might just save you from a 48-hour outage.