AWS Certificate Manager vs AWS Key Management Service: What are the differences?

AWS Certificate Manager (ACM) manages SSL/TLS certificates for AWS services and internal resources, while AWS Key Management Service (KMS) simplifies encryption key creation and control for data protection. Let's explore the key differences between them.

1. Certificate Management vs. Key Management: AWS Certificate Manager (ACM) is a service that provides a managed solution for SSL/TLS certificates. It simplifies the process of obtaining, managing, and deploying certificates for use with AWS services and resources. ACM takes care of the entire certificate lifecycle, including the issuance, renewal, and revocation of certificates. AWS Key Management Service (KMS), on the other hand, is a service that provides secure and scalable key management solutions. It allows users to create and control the encryption keys used to encrypt their data. KMS provides a centralized and secure way to manage keys, and it integrates with various AWS services, which enables seamless encryption and decryption of data.

2. Certificate Provisioning and Integration: ACM is tightly integrated with other AWS services, making it easier to provision and deploy SSL/TLS certificates. It seamlessly integrates with services like Amazon CloudFront, Elastic Load Balancers (ELBs), and Amazon API Gateway, enabling automatic certificate provisioning and renewal. KMS, on the other hand, is more focused on key management and encryption. While KMS can be used to encrypt and decrypt various types of data, it does not provide the same level of integration with AWS services for certificate provisioning and management.

3. Certificate Storage and Inventory: ACM manages the storage and inventory of SSL/TLS certificates. It securely stores the certificates and provides a central repository for managing and tracking the certificates issued and deployed within an AWS account. KMS, on the other hand, does not explicitly manage the storage and inventory of certificates. It focuses on managing encryption keys and providing secure key storage. It is up to the users to store and manage the certificates themselves.

4. Ease of Use and Administration: ACM provides a simplified and user-friendly interface for requesting and managing certificates. It automates many of the complex tasks, such as certificate creation, validation, and renewal, making it easier for users to obtain and deploy SSL/TLS certificates. KMS, while also offering a user-friendly interface, focuses more on advanced key management capabilities. It provides fine-grained access control and auditing features to manage encryption keys securely.

5. Cost Structure: ACM provides free SSL/TLS certificates for use with AWS services such as Amazon CloudFront and Elastic Load Balancers. However, it does not offer the same free certificate provision for use outside of AWS services. KMS, on the other hand, has a different cost structure. It charges users based on the number of requests made to perform cryptographic operations using KMS-managed keys.

6. Scope and Use Cases: ACM is primarily used for managing SSL/TLS certificates within the AWS ecosystem. It is designed to simplify certificate provisioning and deployment for use with AWS services and resources. KMS, on the other hand, has a broader scope and can be used for encrypting and decrypting data across various AWS services, as well as for managing keys used in custom applications.

In summary, ACM focuses on managing SSL/TLS certificates and provides seamless integration with AWS services, while KMS is more focused on key management and encryption. Each service has its own specific use cases and strengths within the AWS ecosystem.