Zero trust architecture
Zero trust is the security model that assumes no implicit trust based on network location — every request, internal or external, must be authenticated, authorised, and continuously verified. The model replaces the perimeter-based 'trust the LAN, distrust the internet' assumption that dominated enterprise security until the mid-2010s.
Zero trust emerged from the recognition that perimeter security fails against insider threats, lateral movement after a breach, and the cloud-and-SaaS-driven dissolution of the perimeter itself. The practical implementation: identity-aware proxies in front of every service, strong authentication (MFA, hardware keys, device attestation), per-request authorisation that re-checks every time, network segmentation that doesn't grant trust by VLAN, and continuous risk scoring that revokes access when behaviour changes. Google's BeyondCorp is the canonical reference; vendor offerings include Cloudflare Access, Tailscale, AWS Verified Access, Okta's identity-aware proxy.
Related terms
- Defense in depth
Defense in depth is the security principle of layering multiple independent controls so that a failure in any one doesn't expose the system — input validation plus parameterised queries plus least-privilege database access plus output encoding plus a WAF.
- Principle of least privilege
The principle of least privilege is the security rule that every user, process, and system should have only the minimum permissions needed to do its job — no extra access 'just in case'.
- Shift-left security
Shift-left security moves security activities — threat modelling, static analysis, dependency scanning, secret detection — earlier in the development lifecycle, ideally into the developer's IDE and PR workflow.