For his thesis, he worked on Solidity project implementing what is known as Confidential Transactions.
It's basically a system where you can send transactions to people on the blockchain without actually revealing the individual amount that you have sent to people.
He thought that this would be a perfect application for the zkSNARKs cryptographic method.
As you can see, you will have to prove something without revealing what it actually is, so he implemented this solidity in a smart contract.
At the moment, it isn't actually possible to implement this because the parameters aren't there for it to work in a solidity smart contract, but with the upcoming Metropolis release, they are implementing these parameters through the use of pre-compiled contracts, as a result, it would be possible for the system to work in that context.
