# Exposure Notification for Automated Contact Tracing (Download only solution)

![](https://3593952043-files.gitbook.io/~/files/v0/b/gitbook-legacy-files/o/assets%2F-MXJvBuZds6XAeA6bQiG%2F-MYPuC_HJu-E0ioKLwyZ%2F-MYPuoQ9RrAnR2xjW2Wy%2FScreenshot%202021-04-16%20at%207.10.43%20PM.png?alt=media\&token=be9211ad-d09b-4161-92e9-f0f1dc45dce3)

For an on-device solution in exposure notification, an infected phone and healthy phones would exchange Bluetooth keys.  Only the infected phone uploads the Bluetooth keys to the server, and then all the other healthy phones download this global key file locally to their phone and see if there's an overlap between the keys that they have and the keys downloaded from the server. As you can see, because it's an on-device calculation and download only, the server does not know anything about John or his contacts. At the same time, if somebody did receive an exposure alert, the server does not know who exactly got the exposure alert.

We have an official exposure notification app deployed in 7 places, details can be found in the link below.

{% embed url="<https://www.pathcheck.org/en/covid-19-exposure-notification-app>" %}

![](https://3593952043-files.gitbook.io/~/files/v0/b/gitbook-legacy-files/o/assets%2F-MXJvBuZds6XAeA6bQiG%2F-Ma-zjOskXiz-37y0G9S%2F-Ma-ztMCv_XQJGKiuYUY%2FScreenshot%202021-05-19%20at%201.07.26%20AM.png?alt=media\&token=a9eb709e-2493-4195-84bd-92e37c8195ab)

{% embed url="<https://youtu.be/GXr7TxD7QKA>" %}

{% embed url="<https://youtu.be/eoLE9OXvxiU>" %}

**References**

* [**Apps Gone Rogue: Maintaining Personal Privacy in an Epidemic**](https://arxiv.org/abs/2003.08567)
* [**Comparing manual contact tracing and digital contact advice**](https://arxiv.org/abs/2008.07325)
* [**Proximity Sensing: Modeling and Understanding Noisy RSSI-BLE Signals and Other Mobile Sensor Data for Digital Contact Tracing**](https://arxiv.org/abs/2009.04991)
* [**Proximity Interference with Wifi-Colocation during the COVID-19 Pandemic**](https://arxiv.org/abs/2009.12699)
* [**Spatial K-anonymity: A Privacy-preserving Method for COVID-19 Related Geo-spatial Technologies**](https://arxiv.org/abs/2101.02556)
* [**COVID-19 Contact-Tracing Mobile Apps: Evaluation and Assessment for Decision Makers**](https://arxiv.org/abs/2006.05812)
* [**Contact Tracing: Holistic Solution beyond Bluetooth**](http://sites.computer.org/debull/A20june/p67.pdf)
* [**Contact Tracing to Manage COVID19 Spread – Balancing Personal Privacy and Public Health**](https://www.mayoclinicproceedings.org/article/S0025-6196\(20\)30424-9/fulltext)
* [**The Architecture of Trust in Contact Tracing**](https://f.hubspotusercontent40.net/hubfs/8097148/documents/evaluating-contact-tracing-apps.pdf)
* [**Adding Location and Global Context to the Google/Apple Exposure Notification Bluetooth API**](https://arxiv.org/abs/2007.02317)