AWS CloudHSM vs AWS Key Management Service: What are the differences?

Introduction

In this article, we will compare AWS CloudHSM and AWS Key Management Service (KMS) based on their key differences. Both services provide secure key management solutions in the AWS cloud, but they have distinct characteristics and use cases.

1. Security and Compliance: AWS CloudHSM offers a dedicated Hardware Security Module (HSM) appliance that is FIPS 140-2 Level 3 compliant. It provides tamper-evident physical protection for cryptographic keys and supports a wide range of security certifications and regulations. On the other hand, AWS KMS is a managed service that abstracts away the underlying HSM infrastructure. It is engineered to comply with various security standards and regulations, including HIPAA, PCI DSS, and ISO 27001.

2. Performance and Scalability: AWS CloudHSM provides high-performance cryptographic operations due to its dedicated HSM appliance. It offers single-tenant access to HSM resources and is designed for low-latency and high-throughput use cases. In contrast, AWS KMS is a scalable service that utilizes a shared infrastructure. While it may not deliver the same level of performance as CloudHSM for extremely demanding workloads, it provides excellent scalability and availability for most applications.

3. Key Ownership and Management: With AWS CloudHSM, customers have full control over their keys as the HSM appliance is physically dedicated. They have exclusive administrative privileges and can manage the lifecycle of keys directly within the HSM. In AWS KMS, keys are managed through the KMS API, and customers retain control over key usage and rotation but do not have direct control over the underlying HSM infrastructure.

4. Integration and Service Availability: AWS CloudHSM integrates with various AWS services using the CloudHSM client software, enabling secure key storage and cryptographic operations within those services. It provides greater flexibility in terms of integration options. AWS KMS, on the other hand, is a native service that seamlessly integrates with other AWS services without requiring any additional software installation.

5. Cost and Pricing Model: AWS CloudHSM involves upfront costs as customers need to provision dedicated HSM appliances. It has an hourly usage fee, which includes the cost of the hardware and maintenance. AWS KMS, being a managed service, has a more flexible pricing model. It charges based on the number of API requests made and any additional features utilized, such as key rotation or custom key stores.

6. Managed Service vs. On-Premises: AWS CloudHSM is an on-premises service where customers directly manage the HSM appliances and their physical security. This gives full control and responsibility to the customer but requires more operational overhead. On the other hand, AWS KMS is a fully managed cloud service that abstracts away the complexities of hardware management, providing a more convenient solution for customers who prefer a serverless key management approach.

In summary, AWS CloudHSM offers dedicated HSM appliances for enhanced security and performance, whereas AWS KMS is a fully managed service that provides scalability, ease of use, and integration with other AWS services. The choice between the two depends on specific use case requirements and preferences regarding control, security, and cost.