Effective key inventory management is critical for maintaining the security and integrity of cryptographic systems. Organizations must define, implement, and evaluate processes and technical measures to track and report on all cryptographic materials throughout their lifecycle. This includes provisioning for relevant legal and regulatory requirements.

Where did this come from?

This article is based on Control ID CEK-21 from the CSA Cloud Controls Matrix v4.0.10, released on 2023-09-26. The full CCM can be downloaded at https://cloudsecurityalliance.org/artifacts/cloud-controls-matrix-v4.

Who should care?

• Security engineers responsible for designing and implementing cryptographic key management systems
• Compliance officers who need to ensure adherence to relevant legal and regulatory cryptography requirements
• Auditors assessing the security and integrity of an organization's cryptographic infrastructure

What is the risk?

Inadequate key inventory management can lead to several adverse events:

• Unauthorized access to sensitive data if keys are not properly secured
• Inability to decrypt data if keys are lost
• Non-compliance with legal/regulatory requirements around key management
• Operational disruption if keys unexpectedly expire or are revoked without a replacement

A robust key inventory management process significantly reduces the likelihood and impact of these risks. However, some residual risk will always remain, especially from insider threats or catastrophic events.

What's the care factor?

For any organization that uses cryptography to protect sensitive data, key inventory management should be a top priority. The risks of poor practices in this area are severe - data breaches, compliance violations, reputational damage, etc. Cutting corners is not advisable given the critical importance of cryptographic keys.

That said, the level of rigor and investment should be commensurate with the sensitivity of the data and systems being protected. Simpler key management practices may suffice for lower-risk scenarios.

When is it relevant?

Key inventory management is relevant whenever an organization is using cryptography for:

• Encrypting data at rest or in transit
• Digitally signing software, emails, documents, etc.
• Authenticating systems or users with digital certificates
• Integrating with PKI or other trust frameworks

It becomes less relevant if cryptography is not widely used, or only used for low sensitivity data. Even then, having a basic inventory is advisable.

What are the trade-offs?

Implementing robust key inventory management has costs and trade-offs:

• Specialized software and hardware (HSMs) can be expensive
• Significant engineering effort to integrate crypto management into applications and workflows
• Reduced agility/speed when strict processes are required to manage keys
• User experience impact if key ceremonies or other manual steps are required frequently

How to make it happen?

1. Assess current key management practices against industry standards like NIST 800-57. Identify gaps and prioritize improvements.
2. Define policies for key lifecycle management - generation, distribution, storage, rotation, retirement. Ensure compliance with relevant regulations.
3. Select and procure a key management system (KMS) that aligns with your requirements. Consider both hosted and on-prem options. Ensure FIPS 140-2 validation.
4. Generate and securely distribute initial keys and certificates to all relevant systems and users. Use hardware security modules (HSMs) for root keys where possible.
5. Configure the KMS to track all key state changes and material movements. Ingest logs into a SIEM for alerting on anomalies.
6. Establish access control policies in the KMS so that only authorized users can view or modify keys.
7. Set up automated key rotation and removal workflows based on crypto period policies. Ensure new keys are distributed before old ones expire.
8. Regularly audit key inventories and review KMS logs for any unexpected activity. Perform periodic penetration testing.
9. Train all relevant personnel on key management policies and procedures. Make secure handling of keys part of performance evaluations.
10. Stay up to date with evolving cryptographic standards and rotate keys/algorithms as needed to maintain security.

What are some gotchas?

• Many KMS require specific permissions to access and manage keys, e.g. kms:Encrypt, kms:DescribeKey. Ensure roles are configured with least privilege.
• Default key rotation periods may not align with your policies. Configure them to meet internal and regulatory requirements.
• Avoid using local key stores for production workloads. Centralized KMS with strong access controls are more secure and compliant.

What are the alternatives?

• Cloud provider KMS services (AWS KMS, Azure Key Vault, etc) can reduce implementation effort, but may not meet all compliance needs
• Hashicorp Vault is a popular open source option for multi-cloud key orchestration
• For some use cases, secrets management tools like AWS Secrets Manager or CyberArk may suffice instead of a full KMS

Explore further

• NIST SP 800-57 provides in-depth recommendations for key management
• CIS Controls v8 3.1-3.4 cover relevant data protection practices
• AWS KMS Best Practices: https://docs.aws.amazon.com/kms/latest/developerguide/best-practices.html

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