Packets hit the edge. The load balancer decides where they go. Every byte matters, and every field can carry secrets. Field-level encryption with an external load balancer is the difference between a secure system and a breach waiting to happen.
Field-level encryption protects sensitive fields in data payloads before they leave the client. The encryption happens at the application layer, but the external load balancer manages the traffic without exposing unencrypted data to intermediate systems. This design ensures that only authorized services can decrypt specific fields. Attackers intercepting traffic only see ciphertext, even if they penetrate network boundaries.
An external load balancer sits outside your application servers. It routes incoming requests, terminates TLS connections, and can operate at Layer 4 or Layer 7. When paired with field-level encryption, the load balancer never needs full plaintext access. Requests can pass through for routing while encrypted fields remain sealed until they reach the target service with the proper keys.
Effective implementation starts with strong encryption algorithms. AES-256-GCM is common for performance and security. Keys should be managed using a centralized, audited key management system. Encrypt at the source, not at the edge. The load balancer should work with existing TLS, but avoid performing decryption of sensitive fields unless absolutely required.