What you'll learn
- Secure design principles
- Zero Trust Architecture (NIST SP 800-207)
- Trust boundaries and data flow diagrams
- Architecture review checklist
Lessons
1Secure design principles
Saltzer & Schroeder's principles still drive design reviews: economy of mechanism (keep it simple), fail-safe defaults, complete mediation (check every access), open design, separation of privilege, least common mechanism and psychological acceptability.
Add modern ones: secure by default, minimise attack surface, assume breach, and design for observability.
2Zero Trust Architecture (NIST SP 800-207)
Zero trust removes implicit trust based on network location. Every request is evaluated by a Policy Decision Point (policy engine + administrator) and enforced by a Policy Enforcement Point.
- Signals: user identity, device health, location, behaviour, data sensitivity.
- Pillars (CISA ZTMM 2.0): Identity, Devices, Networks, Applications & Workloads, Data, plus Visibility, Automation and Governance.
- Start with identity and device posture, then microsegment high-value assets.
3Trust boundaries and data flow diagrams PRO
Draw processes, data stores, external entities and data flows. Each place where data crosses between different trust levels is a trust boundary and needs authentication, authorizat…
Continue this lesson in the platform →4Architecture review checklist PRO
Identity: SSO, MFA, service identities, no shared accounts. Network: private endpoints, segmentation, egress control. Data: classification, encryption at rest and in transit, key o…
Continue this lesson in the platform →Hands-on lab: Zero trust maturity self-assessment
- Pick one application you know well.
- For each CISA ZTMM pillar (Identity, Devices, Networks, Apps, Data), rate it Traditional, Initial, Advanced or Optimal.
- Identify the weakest pillar.
- Write two concrete improvements for it (e.g. 'require compliant device for admin portal').
- Draw a simple data flow diagram and mark the trust boundaries.
Outcome: A one-page zero trust gap analysis.
Practice questions
In NIST SP 800-207, which component makes the access decision?
Answer: Policy Decision Point. The PDP (policy engine + administrator) decides; the PEP enforces.
'Complete mediation' means…
Answer: Check every access request. Every access must be checked, not cached once.
Zero trust primarily removes trust based on…
Answer: Network location. Being 'inside' the network grants nothing by itself.
The full graded assessment (6 questions, pass mark 70%) is in the platform.
Key terms
- Zero trust
- Never trust, always verify; no implicit trust from network location.
- Policy Decision Point
- Zero trust component that evaluates and decides on access requests.
- Policy Enforcement Point
- Zero trust component that enforces access decisions.
- Trust boundary
- Point where data or control passes between different trust levels.
- Microsegmentation
- Fine-grained, workload-level network policy.
- Secure by default
- Products ship with the most secure settings enabled.
See the full cyber security glossary →
Official references
Related courses
Security Foundations & GRC
CIA triad, risk management, frameworks and the controls that hold a security program together.
Data Security & Privacy
Data classification, DLP, encryption and key management, plus GDPR and India's DPDP Act.