Have you ever wondered how biometric data transfer works? You want to check whether do you have a match in a database but without revealing your identity to the database? It is possible if you know what to use. Guess what, it is not as hard you think! Even better now it is available in PHP. Choosing one of two options without letting the other party to know you what you choose, pretty easy and secure. Also possible to implement all of this with PHP without having to know in depth the protocol itself.
This could be used in plenty of cases, the idea of the talk is to introduce the audience to a cryptographic primitive that could be used in different scenarious by making a custom PHP extension and then a library that could be used by other people.