As this book is being written, the two most popular cryptocurrencies are Bitcoin and Ethereum (once in a while, Ripple will take second place). If you ask a simple question to someone who knows a lot about cryptocurrencies, you may get an answer: Bitcoin is just for sending money, but you can create a program on Ethereum. The program can be tokens, auction, or escrow, among many other things. But that is a half-truth. You can also create a program on Bitcoin. Usually, people call this program a script. In fact, it is a must to provide a script in a Bitcoin transaction. A transaction in Bitcoin can be mundane, so if I want to send you 1 BTC (a unit of currency in Bitcoin) and your Bitcoin address is Z, I need to upload a script like this into Bitcoin blockchain:
What's your public key? If the public key is hashed, does it equal Z? If yes, could you...
