verify method
Verifies if the url is valid for the given signature to check if it's an authentic url.
Implementation
bool verify(
String url, String urlEncodedBase64Signature, KeyPair signerPublicKey) {
final String urlSignatureLess = url.replaceAll(
"&" + signatureParameterName + "=" + urlEncodedBase64Signature, "");
final Uint8List payloadBytes = _getPayload(urlSignatureLess);
final String base64Signature =
Uri.decodeComponent(urlEncodedBase64Signature);
return signerPublicKey.verify(payloadBytes, base64Decode(base64Signature));
}