Exposure Notification Reference Key Server

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Getting Started

    How to Deploy
    How to Publish Keys
    How to Download Keys
    Estimating the Cost of Deployment

Design

    Server Deployment Options
    Server Functional Requirements
    Verification Protocol Design
    API Definitions

Temporary Exposure Key (TEK) Downloading via Batches

This page explains how to retrieve publihsed temporary exposure keys (TEKs) from the server by generating batches that can be downloaded by a mobile application. These batches are logical groupings of TEKs published to the server. Keys can be grouped by region and the frequency of batching is configurable. We recommend batches are configured to be generated at most every 4 hours, with a likely time being somewhere between 4 and 24 hours.

Prerequisites

If you haven’t started developing a mobile app, please take a look at the Android Exposure Notifications Reference App.

You need to complete the necessary steps to use the exposure notifications API. You should also ensure that you have taken the steps to comply with the Terms of Service.

Downloading TEKs

In order to download the exposure keys from the exposure notification key server, the first step is to configure exports from the server.

To add these entries, we can use the Admin Console. For instructions on how to launch the console, you can view the deployment documentation.

Once the admin console is launched, you will see a few choices presented.

Select “Create new Export Config”

Creating an export config will generate export files (batches of keys) that are produced on a defined schedule. These will be available for download via the configured storage and/or CDN and downloadable by devices. CDN configuration is external to this server. Most Cloud Providers have a CDN solution that you can leverage.

It is also required that you create a signing key that will be used to sign the export files. This ensures that the batches of keys devices receive are originating from the server and not an unauthorized, potentially malicious, third-party. The signing key must be an asymmetric ECDSA P-256 key, and the public portion must be shared with Google and Apple. If the signing key is invalid, or if the key is not shared with Google and Apple, the Exposure Notification API will not invoke matching on the export.

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