Research results

Dario Fiore, Anaïs Querol and Matteo Campanelli, researchers of the IMDEA Software Institute, have talked about the new framework they have developed, called LegoSNARK, which paper was published at the ACM Conference on Computer and Communications Security.

Dario Fiore, Associate Research Professor, started saying that “in our society we often experience a tension between the privacy of our data and the utility of its use. For example, assume that you want to rent a house and the landlord ask you to prove that your monthly income exceeds the rental fee. Now, you would not like to reveal exactly how much you earn because for example this may induce the landlord to increase the price in the future. So, how can you then make this proof and without revealing too much information. Zero-knowledge proofs are a magical cryptographic tool that allows to prove a statement about private data without revealing more information than the fact that the statement is true”.

The PhD student, Anaïs Querol started showing a physical example of how it is possible to convince the landlord that you can afford the rent. “Suppose that the rent costs 4 coins and we earn 10 coins. We insert those 10 coins inside this opaque coin dispenser, so by the shape of the dispenser at least you can see that I have 3 coins. How can I prove the landlord that I have at least 1 more? It is very simple, I simply get this one out and now you can see that I have 1,2,3 and 4. So the landlord knows that I can afford the apartment, but they have no clue about our spare money”. She ends up saying that this can look quite simple, but in a digital transaction when you have to convince someone on the other side of the world cool mathematical techniques come into play to make it possible!

Matteo Campanelli, post-doctoral researcher, adds that now the emerging technologies like blockchains or cryptocurrencies are pressing out to make all these systems practical. “Recently at IMDEA what we did was tackling two of the main challenges in the space. The two main challenges are one, that these things, the digital analogy of the physical world opaque coin dispensers are very complex and the other is that they are slow. In order to tackle these problems, we develop a framework called LegoSNARK. Basically, we design techniques that allow to construct these systems not in a monolithic way but more modularly. So, think of not a whole piece of clay, but made of different construction blocks of sort, and that’s why we called it LegoSNARK. The interesting thing is that this approach also gives you more efficient zero-knowledge proofs in general”.