Message signing script example

This example shows how to build a solution that will allow proving ownership of a private key. sign_message function produces a hashref containing all the data required to verify you own a bitcoin address or a public key (bitcoin address is deterministically generated from a public key so they are pretty much the same thing), ready to be serialized using JSON for example. verify function accepts this hashref and returns a true or false value, meaning whether the message is verified successfully.