# Introduction

## Face as a credential

Salto XS4 Face's face recognition technology is engineered to provide
convenient, secure access using only a face as a credential. Support
information for the XS4 Face platform is available on the
[Salto Support Site](https://support.saltosystems.com/xs4face/).

## What is XS4 Face?

XS4 Face is a hybrid (cloud and on-premise) solution that enables a face to be
used as a credential.

### Device

The camera unit consists of two parts: a controller and a camera. It detects
the presence of a person, sends an image to the recognition appliance and
displays the result to the user.

### Recognition Appliance (Server)

The recognition appliance is located on-premise and is responsible for image
analysis, detecting fakes (presentation attack detection) and recognising an
enrolled user. When a user enrolls their face, the image is passed to the
appliance, where a biometric template is created and the image is destroyed.

A customer can have an appliance per site, enabling all of their users to be
recognised at all of their sites.

### XS4 Face Cloud

The cloud manages the XS4 Face infrastructure from a single place. It is hosted
in Azure West Europe (Netherlands) and provides the API required to manage
users, their consent and their images.

### Cloud Enrollment Service

The Cloud Enrollment Service is provided by Salto to enable remote enrollment at
scale. It ensures all enrollment images are of sufficient quality and maintains
a copy of all user images to enable system upgrades and disaster recovery.

### Salto Enrollment App

XS4 Face includes a Salto branded enrollment app that makes user enrollment
simple. Users are authenticated using email based codes. The app captures the
user's acceptance of the terms of service for the Enrollment Service, their
enrollment image and their consent to the use of that image for biometric
processing — ensuring GDPR compliance.

Use of the app is optional: a [Level 2 integration](#level-2---enrolling-users)
gives you direct access to the enrollment service features from your own app,
with your own branding.

### Console

The XS4 Face console is the management UI for the face recognition system. Its
primary use is system setup and configuration, enabling appliances to be built
and devices to be commissioned. It also provides diagnostic logging to aid
support teams.

## Adding face recognition to your software solution

The XS4 Face solution integrates with the GT7 family of terminals to provide a
face as a credential. There are two levels of integration with XS4 Face that can
be achieved, depending on your requirements.

### Level 1 - User management

Your membership management system links to Salto XS4 Face Cloud to add, remove
and query users. Users enroll their face for XS4 Face using their own mobile
device and Salto's Cloud Enrollment Service.

### Level 2 - Enrolling users

Instead of using Salto's Enrollment App, the enrollment process is embedded into
your customer's app. Salto's Cloud Enrollment Service still quality checks
enrollment images and manages delivering them to the face recognition appliance
on site.

### Tenant hierarchy

You will be created as a partner within the XS4 Face platform. Each of your
customers is represented as an XS4 Face site. A customer with more than one
physical location can have all of those locations managed within a single XS4
Face site.