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ed55bb9 · Jul 7, 2022

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Packet: Cryptographic Secret Sharing

Girls Talk Math Camp 2022 at UMD

In this problem set, you will learn how to use math to share a secret among a group of people so that they have to work together to learn the secret. This is the cryptographic technique known as secret sharing and is one of the fundamental building blocks of secure multi-party computation, or MPC, which is used by companies like Amazon, Google, and the cryptocurrency Zcash to do computations over private data. The math used in secret sharing is probability and polynomial interpolation, the latter of which is based on concepts you are probably very familiar with from your school curriculum. In this packet, you'll see firsthand how we can use these simple building blocks to achieve seemingly impossible things. As a bonus, you can even try your hand at writing a mathematical proof of security, thereby learning techniques that cryptographers everywhere use to mathematically guarantee the security and privacy of our online infrastructure.