Chapter 5: Introduction to Zero-Knowledge Protocols

As we have already seen with the digital signature, the authentication problem is one of the most important, complicated, and intriguing challenges that cryptography is going to face in the near future. Imagine that you want to identify yourself to someone who doesn't know you online. First, you will be asked to provide your name, surname, and address; going deeper, you will be asked for your social security number and other sensitive data that identifies you. Of course, you know that exposing such data via the internet can be very dangerous because someone might steal your private information and use it for nefarious purposes.

Some time ago, I watched a video that impressed me. I have even decided to insert it into my presentations about privacy and security, and I presented it during an event related to Smart Cities in Silicon Valley where I had been invited to talk. The video starts with an alleged magician who invites...