Introduction to Cryptography & Digital wallet

When it comes to cryptography I love these following sections from Cypherpunk Manifesto (https://www.activism.net/cypherpunk/manifesto.html)

Privacy is necessary for an open society in the electronic age. Privacy is not secrecy. A private matter is something one doesn't want the whole world to know, but a secret matter is something one doesn't want anybody to know. Privacy is the power to selectively reveal oneself to the world.

Privacy in an open society also requires cryptography. If I say something, I want it heard only by those for whom I intend it. If the content of my speech is available to the world, I have no privacy.