Best practices for rotating encryption keys on Cloud Object Storage buckets with ERP data

Cloud Platforms IBM Cloud
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1

Our security team is implementing quarterly encryption key rotation for COS buckets containing ERP financial data. We’re using Key Protect for customer-managed keys, and I want to understand the best practices before we execute the first rotation. The buckets contain about 12TB of data across 450,000 objects - invoices, financial reports, transaction logs.

My main concerns are around downtime and data accessibility during rotation. Does COS automatically re-encrypt all objects when we rotate the root key, or does it use envelope encryption where only the data encryption keys get re-wrapped? Also wondering about the ERP application impact - will there be any service interruption when we rotate keys? Our compliance requirement is quarterly rotation for financial data, but I want to make sure we’re following IBM’s recommended approach for production systems.

2

Let me provide comprehensive guidance on all three aspects of key rotation for your ERP data:

COS Encryption Key Management Architecture:

Cloud Object Storage implements envelope encryption with three key layers:

  1. Root Key (Customer-Managed): Stored in Key Protect, rotated by you, never leaves Key Protect HSM
  2. Bucket Key: COS-managed, wraps individual object DEKs, re-wrapped during root key rotation
  3. Data Encryption Keys (DEKs): Unique per object, encrypts actual data, remains unchanged during rotation

When you rotate the root key in Key Protect, only the bucket key re-wrapping occurs. This is a metadata operation with zero data re-encryption. Your 12TB dataset and 450,000 objects remain untouched. The process completes in seconds regardless of data volume. COS automatically uses the new root key version for subsequent operations without requiring configuration changes.

Key Rotation Process and Best Practices:

For production ERP systems with quarterly rotation requirements:

Pre-Rotation Checklist:

  1. Verify IAM policies grant COS service authorization to Key Protect (action: kms.secrets.rotate)
  2. Confirm no active key disable or deletion operations
  3. Schedule rotation during low-activity window (optional but recommended)
  4. Notify application teams 48 hours in advance
  5. Verify backup/DR systems can access Key Protect

Rotation Execution:

  1. Initiate rotation through Key Protect console or API
  2. Key Protect creates new key version and marks it active
  3. COS receives notification and re-wraps bucket keys automatically
  4. Process completes with zero downtime - applications maintain uninterrupted access
  5. New uploads automatically use new key version

Post-Rotation Validation:

  1. Query Key Protect API to verify new key version is active
  2. Test object upload and download operations
  3. Review Activity Tracker for rotation event logs
  4. Verify ERP application can read existing objects and write new ones
  5. Check Cloud Monitoring dashboards for any error rate increases
  6. Document rotation completion timestamp for compliance records

ERP Data Security Compliance:

For financial data under regulations like SOX, PCI-DSS, or GDPR:

  1. Rotation Frequency: Quarterly rotation meets most compliance frameworks. Some require monthly for highly sensitive data (credit cards, personal health information)

  2. Audit Trail Requirements: Enable Activity Tracker with log retention matching your compliance period (typically 7 years for financial records). Capture these events:

    • kms.secrets.rotate (root key rotation)
    • kms.secrets.read (key access for encryption/decryption)
    • cos.object.write (new object encryption)
    • cos.object.read (object decryption)

  3. Key Version Management: Key Protect retains all previous key versions (disabled but not deleted). This allows decryption of older objects encrypted with previous versions. Never delete old key versions until all data encrypted with them is re-encrypted or archived beyond retention period.

  4. Access Controls: Implement least-privilege IAM policies:

    • COS service: kms.secrets.wrap, kms.secrets.unwrap (not rotate)
    • Security admins: kms.secrets.rotate, kms.secrets.read
    • Application service IDs: cos.object.get (not kms.secrets.* directly)

  5. Separation of Duties: Different teams should manage:

    • Key Protect administration (security team)
    • COS bucket configuration (storage team)
    • ERP application access (application team) No single person should control all three layers.

  6. Disaster Recovery: Configure Key Protect with multi-region deployment. If primary region fails, COS can retrieve keys from secondary region. Test DR procedures annually including key access failover.

Application Impact Mitigation:

Your ERP application should be unaffected if using current IBM COS SDK versions (2020+). Modern SDKs handle key version changes transparently. However, verify:

  1. SDK version supports automatic key version refresh
  2. Application doesn’t cache Key Protect credentials beyond token expiration (typically 60 minutes)
  3. Connection pools refresh after credential rotation
  4. Retry logic handles transient Key Protect API errors during rotation

For older applications, schedule rotation during maintenance windows and perform application health checks immediately after. Monitor error logs for “key not found” or “decryption failed” errors indicating SDK issues.

Rollback Procedures:

If issues occur post-rotation:

  1. Key Protect allows reverting to previous key version (console or API)
  2. COS automatically detects version change and re-wraps bucket keys
  3. Applications regain access within minutes
  4. Investigate root cause before attempting next rotation

Common rollback triggers: IAM permission errors, SDK incompatibility, or Key Protect regional outage during rotation.

Implementing these practices ensures your quarterly rotation meets compliance requirements while maintaining zero-downtime operation for your ERP systems.

3

That’s reassuring about the zero downtime. How do we verify that the rotation completed successfully? Is there a way to audit which key version was used to encrypt specific objects, especially for compliance reporting?

4

We never needed rollback in production, but tested it quarterly. Main trigger would be if applications can’t decrypt objects after rotation - usually indicates SDK issues or IAM permission problems. Monitor error rates closely for 24 hours post-rotation.

5

Key Protect provides rotation history through the API and console. You can query key versions and see rotation timestamps. For object-level verification, COS object metadata includes the key version ID used for encryption. Use the HEAD object API to retrieve metadata without downloading the object itself. Activity Tracker logs all key rotation events with details about which COS buckets were affected. Set up alerts in Cloud Monitoring to notify your team when rotations complete. For compliance reports, export Activity Tracker logs showing rotation dates and affected resources. Most auditors accept this as evidence of proper key management practices.