Secure Systems Design

The four fundamental principles of secure system design according to the BDEW Whitepaper 'Secure Systems'.

BDEW Whitepaper 'Secure Systems'

The German Association of Energy and Water Industries (BDEW) defines four fundamental principles for secure system design in their whitepaper on 'Requirements for Secure Control and Telecommunication Systems'. These principles form the foundation for protecting critical infrastructure.

The Four Principles

1. Security by Design

Security must be built into the system architecture from the beginning. It cannot be added retroactively as an add-on.

Implementation in Signando CA: Air-gapped operation as core principle, YubiHSM integration for non-extractable keys.

Implementation in Signando REST: OpenAPI schema as security contract, allowlist approach, bidirectional validation.

2. Minimal Need to Know

Each component should only receive the information and permissions it needs for its task. This minimizes damage if a component is compromised.

Implementation in Signando CA: Separation of Root CA, Intermediate CA, Certificate Manager and Revocation/OCSP components.

Implementation in Signando REST: 4 isolated NATS instances with strict network separation.

3. Defence in Depth

Multiple security layers protect the system. If one layer is breached, the other layers catch the attack.

Implementation in Signando CA: Multi-layer protection: Air-gap + HSM hardware + cryptographic license verification.

Implementation in Signando REST: 4-stage architecture: Frontend, Request Validator, Backend Proxy, Response Validator.

4. Redundancy

Critical security functions should be redundant. Failure of one component must not lead to failure of the entire security concept.

Implementation in Signando CA: Air-gapped Root CA process combined with HSM hardware protection for key redundancy.

Implementation in Signando REST: Kubernetes-native design enables horizontal scaling. Fail-secure behavior.

Implement Secure Systems

Learn how Signando REST implements BDEW principles for your API infrastructure.

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