Reusable Face Authentication
Most identity checks compare a document photo to a selfie once, at onboarding. Reusable face authentication turns that face into a persistent, reusable authenticator: the user enrolls their face once, and can then prove "it's still me" later with just a selfie — no document, no re-onboarding.
When to use it
- Biometric step-up — require a fresh selfie match before a high-risk action (large payment, credential change, re-KYC).
- Returning-user verification — re-verify a user on a new device or session.
- Passwordless / frictionless login (forward-looking) — sign in with a selfie instead of a password.
How it differs from Face Match
| Face Match | Reusable Face Authentication | |
|---|---|---|
| Scope | One verification | Persistent, per user (external_id) |
| Input | Document photo + selfie | Selfie alone |
| Repeatable | Yes, but needs the document each time | Yes, no document needed |
| Use case | Onboarding | Step-up, login, re-verification |
How it works
- Enroll — send a selfie once. The API derives a 512-dim face embedding (MobileFaceNet/ArcFace) and stores it encrypted as a template. A raw photo is never kept. Consent is required.
- Challenge — for each authentication, request a single-use, time-boxed nonce (anti-replay).
- Authenticate — send a fresh selfie with the challenge. The API runs passive liveness, compares embeddings by cosine similarity, and returns the score and a pass/fail against your threshold.
Privacy & security
- Consent is required to enroll; enrollment without it is rejected.
- Templates are encrypted at rest (AES-256-GCM) and bound to the owner, so a ciphertext can't be moved between users.
- Liveness is enforced on enroll and authentication — a printed photo or screen replay of the enrolled face will not authenticate.
- Deletion (
DELETE /face/templates/{external_id}) erases the template immediately; templates are also swept by a retention policy when unused. - The embedding is never returned by any endpoint.
Getting started
See the Reusable Face Authentication API reference for the endpoints, request/response shapes, and the full flow.