4.1.4. Data Encryption in Transit (ACM, ELB/CloudFront TLS)

💡 First Principle: Data encryption in transit protects information moving between systems, preventing eavesdropping and tampering, ensuring secure communication channels and data confidentiality/integrity.

Scenario: You need to ensure all web traffic to your application, hosted on EC2 instances behind an ALB, is encrypted using HTTPS. You also need to encrypt traffic between your EC2 instances and an Amazon S3 bucket for private data transfer.

Encryption in transit (or in-flight encryption) safeguards data as it travels across networks, such as between clients and AWS services, or between different AWS services within the cloud. This prevents unauthorized parties from intercepting or modifying data while it is being transmitted.

Key Concepts and Services for Data Encryption in Transit:

• TLS (Transport Layer Security): (The cryptographic protocol widely used for securing communication over networks, particularly for HTTPS on the web.) Fundamental for encrypting data streams, ensuring privacy and preventing eavesdropping.
• AWS Certificate Manager (ACM): (A service that lets you easily provision, manage, and deploy public and private SSL/TLS certificates.) ACM handles certificate provisioning, renewal, and deployment to integrated AWS services.
• Elastic Load Balancing (ELB): (ALB and NLB) can terminate TLS connections from clients, decrypting traffic before sending it to backend instances. They can also re-encrypt traffic to backend instances.
• Amazon CloudFront: (A CDN that securely delivers data.) Uses TLS to encrypt communication between users and Edge Locations, and often to origin servers as well.
• VPC Endpoints (Interface): Enable private and encrypted communication between your VPC and supported AWS services (e.g., DynamoDB, Kinesis), bypassing the public internet.

⚠️ Common Pitfall: Not re-encrypting traffic between the load balancer and backend instances, leaving internal network traffic unencrypted.

Key Trade-Offs: End-to-end encryption (more secure, but potentially more complex to configure) versus encryption only at the edge (simpler, but internal traffic is unencrypted).

Reflection Question: How would you implement data encryption in transit using AWS Certificate Manager (ACM) (for SSL/TLS certificates) with an ALB and leveraging VPC Interface Endpoints (for S3) to secure communication channels and ensure data confidentiality?