IMDEA Software Institute Phd student Luca Nizzardo, together with his colleagues Matteo Campanelli (City College of New York) and Steven Goldfeder (Princeton University), coordinated by Professor Rosario Gennaro (City College of New York), showed that Zero-Knowledge Contingent Payments (ZKCP), a well-known protocol for the fair exchange of digital goods over the blockchain, is insecure in its current form. In their last paper, after showing a practical attack, they propose a fix for ZKCP, and also extend this primitive to a new class of problems. The result has been recently highlighted both by the Zcash Blog and the Princeton “Freedom to Thinker” Blog. The research project has been developed at Center For Algorithms and Interactive Scientific Software (CAISS), directed by Rosario Gennaro at City College of New York, in Spring 2017. Luca’s stay at CAISS has been funded both by City University of New York and the IMDEA Software Institute.