Timing-Safe Re-Authentication: Single-Source-of-Truth UI State

What Shipped

When a customer chooses a sign-in method on our re-authentication prompt, their selection stays put. Background identity validation continues to run as before — it does not override the customer's choice.

The visible outcome is predictable behaviour for the person in front of the screen. The audit-friendly outcome is a single source of truth for what the customer chose and when.

Why It Matters

For publishers and e-commerce sites operating in the EU, GDPR Art. 32 ("security of processing") requires appropriate technical measures to protect personal data. Predictable authentication-state behaviour is one such measure: a customer who selects a method should be able to act on that selection without surprise overrides.

ENISA Authentication Lifecycle guidance (2023) frames the same expectation. Asynchronous identity validation should not silently alter the actions a customer is about to take — doing so creates an ambiguous record for compliance reviewers and an unpredictable experience for users.

OWASP ASVS Level 1 (V2.2) makes "predictable authentication UI" an explicit baseline. Our re-authentication interface meets that baseline by treating customer selection as authoritative and validating identity in the background without disturbing it.

Where to Read More

See the full quarterly review and rollout notes at /achievements.

Legal basis for our authentication processing is documented in our DPIA.