Maybe you still remember the times of good old analogue cameras. They had a film , which had to be send to be developped. You made some really good photos of your friend and for good reason you don’t wanted them to be seen by anybody else.
However the guy developping the film maybe would have looked at them ? Well, here is where “homomorphic encryption” comes into play.
Now it’s possible to analyze and develop data without ever decrypting it and with hopefully nobody else but you knowing what’s going on.
This can be used for analyzing data which contains private information like your income, the amount of your savings and so on. It can also be used to solve the millionaires problem. A quite funny problem where two millionaires want to know which one of them is richer but no one wants to tell how much many he actually has.
There is actually one project developped by MIT since 2015 which is blockchain supported and probably let’s you try out that think. It’s on http://www.enigma.co .
There is one slight drawback , which pulls down the now rising euphory a bit. In order for this homomorphic encryption to work noise has to be created with every operation. When there is too much noise accumulating or piling up the data is of no use anymore or in other words just undecipherable.
To avoid this – well not desirable result – there are so called refresh keys which refresh the data without revealing its content. Johann Höchtl was so friendly to provide this highly complex topic in a quite easy understandable way and even provides the slides of his presentation on http://www.slideshare.net/jhoechtl .