TimestampSignCallback typedef

TimestampSignCallback = Future<Uint8List?> Function(Uint8List tsq)

Timestamp request callback

Example using dart:io

final url = Uri.parse('http://ts.ssl.com');
final client = HttpClient();
final request = await client.postUrl(url);
request.headers.contentType =
    ContentType('application', 'timestamp-query');
request.contentLength = tsq.lengthInBytes;
request.add(tsq);
final response = await request.close();
final tsr =
    await response.reduce((previous, element) => previous + element);
if (response.statusCode != 200) {
  throw Exception(utf8.decode(tsr));
}
return Uint8List.fromList(tsr);