AWS CloudHSM vs AWS KMS

Introduction

In the realm of cloud security, managing cryptographic keys is a critical aspect. AWS offers two primary solutions for this: AWS CloudHSM and AWS Key Management Service (KMS). Both have their unique features and use cases. This blog post aims to provide a comparative overview to help you choose the right service for your needs.

Tenancy and Compliance

• AWS KMS: Operates in a multi-tenant environment, where infrastructure is shared across multiple AWS customers. Despite the shared environment, KMS maintains robust security.
• AWS CloudHSM: Offers a single-tenant setup, giving you dedicated access to HSM instances. This is ideal for scenarios demanding the highest level of isolation and control.

Key Management and Types

• AWS KMS:
  • Offers three types of keys: AWS Owned, AWS Managed, and Customer Managed Keys (CMKs).
  • Supports symmetric and asymmetric keys, along with digital signing.
• AWS CloudHSM:
  • Provides Customer Managed CMKs, placing complete control of key management in the user’s hands.
  • In addition to symmetric and asymmetric keys, it supports digital signing and hashing.

Accessibility and Performance

• AWS KMS: Keys are accessible across multiple AWS regions, with key replication features for enhanced accessibility.
• AWS CloudHSM: Keys are deployed within a VPC and can be shared across VPCs through VPC peering. Offers SSL/TLS Acceleration and Oracle TDE Acceleration, catering to high-performance requirements.

Access, Authentication, and Availability

• AWS KMS: Leverages AWS IAM for access control and authentication.
• AWS CloudHSM: Requires users to create and manage their permissions, offering granular control.
• In terms of availability, KMS is managed by AWS, while CloudHSM allows for the addition of multiple HSMs across different AZs.

Auditing and Pricing

• Audit Capability:
  • AWS KMS: Supports AWS CloudTrail and CloudWatch.
  • AWS CloudHSM: Offers the same, plus Multi-Factor Authentication (MFA) support for additional security.
• Free Tier:
  • AWS KMS: Available, making it a cost-effective option for smaller scale uses.
  • AWS CloudHSM: No free tier, which might influence decision-making for cost-conscious projects.

Conclusion

Choosing between AWS CloudHSM and AWS KMS depends on our specific needs. For organizations looking for a cost-effective, integrated solution for standard key management tasks, AWS KMS is ideal. AWS CloudHSM, on the other hand, is suited for organizations with stringent compliance requirements and a need for a higher degree of control and performance.