Prove identity and ownership of a Ripple secret key using digital signatures
var privateKey = new PrivateKey('shpwJtZ5YmbSMWLhGAPvs4w4pgWqb');
var publicKey = new PublicKey('rnw7J57JRZqzj5QgYmpK7z3uL6mVYWvVsA');
var message = new Message('important information to verify');
var signer = new Signer(privateKey);
var signature = signer.sign(message);
var verifier = new Verifier(publicKey);
assert(verifier.verify(message, signature));