Key takeaways
- Elastic Cloud supports customer-managed keys (BYOK) for primary data and snapshots across AWS KMS, Azure Key Vault, and Google Cloud KMS.
- Enterprise organizations retain full cryptographic custody, enabling independent access revocation, scheduled key rotation, and granular audit trails.
- Customer-managed encryption directly satisfies stringent regulatory standards including PCI-DSS, HIPAA, and FERPA by enforcing separation of duties.
- Adopting BYOK introduces operational overhead, including measurable I/O latency, computational resource consumption, and the risk of complete cluster outages upon key misconfiguration.
- The feature requires an Enterprise tier subscription and supports both net-new deployments and in-place transitions for running production clusters.
Elastic Cloud allows enterprises to bring their own encryption keys (BYOK) to protect search data and snapshot storage at rest across Amazon Web Services, Microsoft Azure, and Google Cloud Platform. While Elastic has historically provided default encryption keys on hosted clusters, customer-managed keys (CMK) give security teams direct cryptographic custody, automated key rotation, complete auditability, and immediate revocation control from their native cloud key management systems. This architecture directly addresses strict compliance mandates under PCI-DSS, HIPAA, and FERPA, while protecting against unauthorized data exposure. However, shifting to customer-managed keys introduces architectural dependencies, potential I/O latency, and the operational risk of self-inflicted outages if access policies fail.
Regulatory compliance and storage threat models
Data stored in managed cloud environments faces distinct security risks that differ fundamentally from network transmission threats. Encryption in transit protects data moving between client endpoints and search ingest pipelines, but encryption at rest safeguards information written to persistent storage volumes, shared distributed filesystems, and long-term object stores.
For enterprise IT leaders and Chief Information Security Officers (CISOs), deploying encryption at rest defends against three primary threat scenarios:
- Physical hardware exposure: Decommissioned solid-state drives or storage units removed from cloud provider facilities cannot be extracted or read without the associated cryptographic material.
- Accidental data leakage: Storage misconfigurations, orphaned snapshots, or inadvertent permission escalations inside adjacent cloud infrastructure do not expose plaintext records when files remain encrypted with isolated keys.
- Multi-tenant infrastructure compromise: An operational breach within a cloud service provider cannot expose underlying database contents across tenant boundaries if key management sits outside the hosting provider’s custody.
Beyond baseline threat mitigation, regulatory pressure remains the single largest catalyst for customer-managed key adoption. Frameworks such as the Payment Card Industry Data Security Standard (PCI-DSS), the Health Insurance Portability and Accountability Act (HIPAA), and the Family Educational Rights and Privacy Act (FERPA) explicitly demand rigorous key lifecycle controls. Under many federal and financial standards, delegating total key custody to a SaaS vendor fails audit scrutiny; regulators require cryptographic separation of duties where only the data owner holds the authority to decrypt or shred stored records.
How multi-cloud envelope encryption operates
To implement BYOK across diverse hosting environments, Elastic Cloud relies on an envelope encryption model. In this design, the actual database files, index shards, and snapshot blobs are encrypted using local, symmetric Data Encryption Keys (DEKs). These DEKs are never written to disk in unencrypted form. Instead, they are encrypted (wrapped) by a Key Encryption Key (KEK)—the customer master key managed inside the client’s cloud KMS account.
Under this division of responsibilities, Elastic Cloud never stores or views the customer’s root cryptographic key material. When an Elasticsearch node starts or needs to access encrypted storage blocks, the platform sends an API request to the customer’s cloud KMS service to unwrap the necessary DEK. The unwrapped key remains solely in volatile memory during active operations.
According to Elastic’s security architecture guidance, integration is supported across the three major hyperscalers:
- Amazon Web Services (AWS KMS): Administrators create a symmetric single-region key or multi-region replica key, grant Elastic’s service principal decrypt and generate data key rights, and provide the Amazon Resource Name (ARN) via the Elastic Cloud console or management API.
- Microsoft Azure Key Vault: Organizations provision an Azure Key Vault instance, generate an RSA key, configure key access policies or Azure RBAC for the Elastic enterprise application, and supply the Key Identifier URI.
- Google Cloud Key Management Service (GCP Cloud KMS): Platform teams establish a key ring and cryptographic key within the target GCP project and region, assigning the Cloud KMS CryptoKey Encrypter/Decrypter role to Elastic’s service identity using the Google Cloud key resource name.
Crucially for operational teams managing production workloads, Elastic Cloud supports in-place customer encryption key transitions. Security teams are not forced to migrate data to greenfield clusters; existing deployments can be updated to adopt customer-managed keys through a rolling plan change that keeps nodes accessible throughout the transition.
Cloud KMS integrations and architectural differences
Selecting between provider-managed and customer-managed encryption fundamentally alters operational responsibility, audit scope, and disaster recovery processes. While Elastic-managed keys minimize operational friction, they leave key control within the application layer.
| Architectural Dimension | Elastic-Managed Keys (Default) | Customer-Managed Keys (BYOK) |
|---|---|---|
| Key Custody | Elastic platform infrastructure | Customer cloud KMS (AWS, Azure, or GCP) |
| Hyperscaler Support | Abstracted across all supported regions | AWS KMS (ARN), Azure Key Vault (Key ID), GCP KMS (Resource Name) |
| Access Revocation | Requires service ticket or cluster deletion | Instant cryptographic cut-off via customer KMS console or API |
| Audit Trail | Internal vendor operational logs | Native AWS CloudTrail, Azure Monitor, or GCP Cloud Audit Logs |
| Key Lifecycle Control | Managed automatically by Elastic | Customer schedules rotation, versioning, and retention policies |
| Subscription Level | Standard / Included across all tiers | Requires Enterprise subscription tier |
One critical operational requirement across all three providers is geographic affinity: the customer master key must reside in the exact same cloud region as the Elastic Cloud deployment. Attempting to point a deployment in Europe West to a KMS key provisioned in US East introduces severe network latency during key retrieval and violates local data residency policies.
Performance penalties and key governance risks
While customer-managed encryption satisfies compliance and governance standards, it is not without operational cost. Engineering leaders must evaluate trade-offs in three distinct areas before initiating broad rollouts:
First, cryptographic processing incurs a computational tax. Encrypting data at ingestion and decrypting storage segments during search queries consumes CPU cycles and can increase disk I/O latency. While modern server processors leverage hardware-accelerated AES-NI instructions to limit this impact, high-throughput search clusters running heavy aggregations or high-frequency log ingest may experience minor throughput degradation.
Second, reliance on an external KMS introduces an external point of failure. If an enterprise security engineer inadvertently deletes an IAM role, modifies a key policy, or revokes permissions, Elastic Cloud will fail its periodic key verification checks. When a key is unavailable, nodes cannot unwrap data keys, immediately halting read and write operations. While “cryptographic shredding”—the deliberate revocation of a key to render data permanently inaccessible—is a valuable defense against active compromise, accidental shredding represents an irreversible operational disaster.
Third, procurement and staffing costs expand. Enabling customer-managed keys requires an Elastic Cloud Enterprise subscription, representing a higher software investment than standard tiers. Additionally, enterprises must account for hyperscaler KMS charges, which accrue based on key storage duration and the volume of cryptographic API calls generated during cluster scaling and snapshot management. Cross-functional coordination between identity teams, platform engineers, and database administrators becomes mandatory.
Bottom line
Customer-managed encryption in Elastic Cloud provides enterprise security leaders with necessary cryptographic autonomy across multi-cloud deployments. For organizations navigating strict compliance regimes like HIPAA or PCI-DSS, or those operating under strict Zero Trust mandates, the ability to control key rotation, review audit logs in native SIEM platforms, and execute instant access revocation outweighs the operational overhead.
However, BYOK should not be treated as a default configuration for every cluster. Engineering teams must weigh the real costs: mandatory Enterprise licensing, added hyperscaler KMS expenses, minor I/O latency, and the operational responsibility of managing key availability without triggering self-inflicted outages. Organizations should establish strict IAM change-management guardrails and test recovery procedures before migrating mission-critical data to customer-managed keys.
Sources: Elastic Blog: Encryption at rest in Elastic Cloud, Elastic Cloud Documentation: Use a customer-managed encryption key.
