AWS offers several services for managing sensitive data, each tailored to specific use cases, from storing and rotating secrets to managing encryption keys. Here’s how AWS Secrets Manager, AWS Key Management Service (KMS), and AWS Systems Manager Parameter Store differ, including the types of encryption they support.
1. AWS Secrets Manager
- Primary Purpose: Securely stores, manages, and rotates application secrets like API keys, database passwords, and other sensitive credentials.
- Key Features:
- Automatic Secret Rotation: Supports automatic rotation for supported databases and custom rotation for other secrets.
- Encryption: Encrypts secrets using AWS KMS symmetric keys (AES-256).
- Access Control: Integrates with AWS IAM policies for managing access.
- Versioning and Audit Logging: Maintains previous secret versions and logs access with AWS CloudTrail.
- Maximum Value Size: Up to 64 KB.
- Cost: Charges apply per stored secret and per 10,000 API calls.
- Ideal Use Case: Storing sensitive secrets that need regular rotation, especially in high-security environments.
2. AWS Key Management Service (KMS)
- Primary Purpose: Manages cryptographic keys for data encryption, digital signatures, and data integrity.
- Key Features:
- Symmetric and Asymmetric Key Support:
- Symmetric Keys: Uses AES-256 for efficient data encryption/decryption.
- Asymmetric Keys: Supports RSA key pairs (2048 and 3072-bit) for encryption/decryption and Elliptic Curve (ECC) key pairs (NIST P-256, P-384, and P-521) for digital signatures.
- HMAC (Hash-based Message Authentication Code): Supports HMAC keys for message authentication.
- Data Encryption: Commonly used to encrypt data in AWS services (S3, DynamoDB) and application data.
- Fine-Grained Access Control: Allows detailed permission management for each key.
- Key Rotation: Supports automatic rotation for symmetric keys.
- Cost: Charged per customer-managed key and API request; AWS-managed keys are often free in certain services.
- Ideal Use Case: Managing cryptographic keys for encryption, data integrity, and compliance requirements.
3. AWS Systems Manager Parameter Store
- Primary Purpose: Stores configuration data and secrets in a structured, hierarchical format for easy access.
- Key Features:
- Hierarchical Parameter Organization: Organizes configuration data for different environments (e.g., dev, prod).
- Encryption: Encrypts sensitive data using AWS KMS symmetric keys (AES-256), if configured.
- Access Control and Audit Logging: Integrates with IAM for access management and logs access with CloudTrail.
- Standard and Advanced Parameters: Standard parameters support values up to 4 KB (free), while Advanced parameters support values up to 8 KB (paid).
- Maximum Value Size: 4 KB for Standard, 8 KB for Advanced.
- Cost: Standard parameters are free; Advanced parameters are billed based on storage and API requests.
- Ideal Use Case: Storing application configuration data or small secrets that don’t require rotation, in a structured way.
Summary of Key Types and Supported Encryption
| Feature | AWS Secrets Manager | AWS Key Management Service (KMS) | AWS Systems Manager Parameter Store |
|---|---|---|---|
| Primary Use | Secret storage & rotation | Key management & encryption | Configuration data & small secrets |
| Supported Key Types | Symmetric (AES-256) via KMS | Symmetric (AES-256), RSA, ECC, HMAC | Symmetric (AES-256) via KMS |
| Automatic Secret Rotation | Yes | Symmetric keys only | No |
| Data Encryption | Yes, via KMS | Yes, supports custom encryption keys | Optional with KMS |
| Max Value Size | 64 KB | Not applicable | 4 KB (Standard), 8 KB (Advanced) |
| Ideal Use Case | Rotating, sensitive secrets | Encryption, compliance, and signatures | Configuration & non-rotated secrets |
Key Takeaways
- AWS Secrets Manager is the best choice for sensitive secrets that need rotation and regular management.
- AWS KMS is ideal for encryption and managing cryptographic keys, supporting various key types for encryption, digital signatures, and integrity verification.
- AWS Parameter Store works well for organizing configuration data or small secrets without complex rotation needs.
By selecting the right service based on key types, rotation needs, and use cases, you can build a secure and efficient strategy for managing secrets and encryption in AWS.
