[FEATURE] Add the ability for signing and verify messages. about wavesgui HOT 2 OPEN

axlsign.openMessage = function(publicKey, signedMsg) {
  checkArrayTypes(signedMsg, publicKey);
  if (publicKey.length !== 32) throw new Error('wrong public key length');
  var tmp = new Uint8Array(signedMsg.length);
  var mlen = curve25519_sign_open(tmp, signedMsg, signedMsg.length, publicKey);
  if (mlen < 0) return null;
  var m = new Uint8Array(mlen);
  for (var i = 0; i < m.length; i++) m[i] = tmp[i];
  return m;
};

axlsign.sign = function(secretKey, msg, opt_random) {
  checkArrayTypes(secretKey, msg);
  if (secretKey.length !== 32) throw new Error('wrong secret key length');
  if (opt_random) {
    checkArrayTypes(opt_random);
    if (opt_random.length !== 64) throw new Error('wrong random data length');
  }
  var buf = new Uint8Array((opt_random ? 128 : 64) + msg.length);
  curve25519_sign(buf, msg, msg.length, secretKey, opt_random);
  var signature = new Uint8Array(64);
  for (var i = 0; i < signature.length; i++) signature[i] = buf[i];
  return signature;
};

axlsign.verify = function(publicKey, msg, signature) {
  checkArrayTypes(msg, signature, publicKey);
  if (signature.length !== 64) throw new Error('wrong signature length');
  if (publicKey.length !== 32) throw new Error('wrong public key length');
  var sm = new Uint8Array(64 + msg.length);
  var m = new Uint8Array(64 + msg.length);
  var i;
  for (i = 0; i < 64; i++) sm[i] = signature[i];
  for (i = 0; i < msg.length; i++) sm[i+64] = msg[i];
  return (curve25519_sign_open(m, sm, sm.length, publicKey) >= 0);
};

// function accepts buffer with private key and an array with dataToSign
            // returns buffer with signed data
            // 64 randoms bytes are added to the signature
            // method falls back to deterministic signatures if crypto object is not supported
            this.nonDeterministicSign = function(privateKey, dataToSign) {
                var crypto = window.crypto || window.msCrypto;
                var random;
                if (crypto) {
                    random = new Uint8Array(64);
                    crypto.getRandomValues(random);
                }

                var signature = axlsign.sign(privateKey, new Uint8Array(dataToSign), random);

                return this.base58.encode(signature);
            };

            // function accepts buffer with private key and an array with dataToSign
            // returns buffer with signed data
            this.deterministicSign = function(privateKey, dataToSign) {
                var signature = axlsign.sign(privateKey, new Uint8Array(dataToSign));

                return this.base58.encode(signature);
            };

            this.verify = function(senderPublicKey, dataToSign, signatureBytes) {
                return axlsign.verify(senderPublicKey, dataToSign, signatureBytes);
            };