UK Digital Identity: The Architecture Behind GOV.UK One Login

UK Digital Identity: The Architecture Behind GOV.UK One Login

GOV.UK One Login represents the UK’s most ambitious step toward a unified national authentication layer. Built around OpenID Connect and FIDO2, the platform eliminates passwords and introduces phishing-resistant multi-factor authentication as standard. Underpinning this framework is the UK Digital Identity & Attributes Trust Framework, which governs Identity Service Providers (IDSPs) through certification and cryptographic assurance.

The architecture emphasises decentralisation. No central identity database exists. Instead, device-bound keys—stored in secure enclaves or TPMs—sign authentication assertions, verified by departmental relying parties through mutual TLS and JSON Web Tokens (JWT). Data minimisation ensures each service receives only what’s necessary, enforced by zero-knowledge proof systems such as SD‑JWT.

Security guidance is shaped by the National Cyber Security Centre, focusing on supply-chain resilience, key rotation, and zero-trust principles. Audit transparency aligns with ICO data protection standards, while federated isolation between departments prevents correlation attacks.

Globally, One Login aligns with EU eIDAS 2.0 and Singapore Singpass. Both demonstrate that device-held credentials, selective disclosure, and independent audits deliver not only usability but also privacy preservation. The UK model’s success hinges on open APIs, algorithm agility (NIST PQC), and transparent governance.