Defense-in-depth and Role Authentication for Microservice Systems.

Microservices are a widely deployed pattern for implementing large-scale distributed systems. However, in order to harden the overall system and when crossing datacenter boundaries, the authenticity and confidentiality of microservice calls have to be secured even for internal calls. Since most microservice systems employ HTTP-based approaches, TLS communication is usually used to secure the communication channels. However, TLS by itself provides only link-level security. Authentication options are limited or alternatively must be implemented in the application code. As a result, microservice systems often lack proper defense in depth. In this paper we present how standard cryptographic primitives can be combined to provide a flexible communication system providing a high level of security even when easy to manage low-entropy authentication secrets are used. Furthermore, the approach provides encryption, forward secrecy and protection against replay attacks even for out-of-order communication.