# Secure Multi-Party Computation

![](https://3593952043-files.gitbook.io/~/files/v0/b/gitbook-legacy-files/o/assets%2F-MXJvBuZds6XAeA6bQiG%2F-MZ4GssDwaHkwBslwsqD%2F-MZ4H3VOZTm01tD6OhYs%2FScreenshot%202021-04-25%20at%2012.37.56%20AM.png?alt=media\&token=3a495419-b1af-4bce-87a2-e418d8d5503a)

Let's look at the third method, which is secure MPC. Imagine Jane wants to know how many phones are reporting fever. John sending “one”  means he has a fever and “zero” means he does not. To do this, John’s phone sends “70” to server P on the left and the number “minus 69'' to server Q on the right. Of course, 70 minus 69 is one. The second phone sends 38 and -37. Third sends 42 and -42. The Left server adds up to 150, and the right server to -148. And that leads to the answer 2 people with fever which Jane sees without knowing about John or his fever status.

The goal behind using secure MPC in our toolkit is to **facilitate anonymous symptoms reporting** by the public, without compromising their individual privacy.

{% embed url="<https://en.wikipedia.org/wiki/Secure_multi-party_computation>" %}

{% embed url="<https://crypto.stanford.edu/prio/>" %}