Dart

Combine Timestamp Reply and Content File into a TimeStampData

See more ASN.1 Examples

Demonstrates how to combine a timestamp reply (RFC 3161) with a data file (any type of file) to create a TimeStampData structure (RFC 5544). Dart

import 'package:chilkat/chilkat.dart';

void main() {
  // This example requires the Chilkat API to have been previously unlocked.
  // See Global Unlock Sample for sample code.

  // Also see this example:
  // Send a TimeStamp Request to a TimeStamp Authority and get the Response

  // Load a timestamp reply file
  final bdTsr = CkBinData();
  try {
    bdTsr.loadFile('qa_data/tsd/sample.tsr');
  } on ChilkatException {
    print('Failed to load timestamp reply file.');
    return;
  }

  // Load the tsr into an ASN.1 object.
  final asnTsr = CkAsn();
  try {
    asnTsr.loadEncoded(bdTsr.getEncoded('base64'), 'base64');
  } on ChilkatException catch (e) {
    print(e.lastErrorText);
    return;
  }

  // Get the timestamp reply as XML.
  final xmlTsr = CkXml();
  xmlTsr.loadXml(asnTsr.asnToXml());

  // The timestamp reply XML begins like this:
  // We'll want to remove the 1st "sequence" subtree.

  //     <?xml version="1.0" encoding="utf-8"?>
  //     <sequence>
  //         <sequence>       <---- Remove this sub-tree.
  //             <int>00</int>
  //             <sequence>
  //                 <utf8>Operation Okay</utf8>
  //             </sequence>
  //         </sequence>
  //         <sequence>   
  //             <oid>1.2.840.113549.1.7.2</oid>
  //             <contextSpecific tag="0" constructed="1">
  //             ...

  // Remove the 1st sub-tree..
  xmlTsr.removeChildByIndex(0);

  // In this example, the data file we're combining with the timestamp into a timestampData is a .p7m.
  // However, it can be any type of file (text or binary), it doesn't matter..
  final bdContent = CkBinData();
  try {
    bdContent.loadFile('qa_data/tsd/sample.p7m');
  } on ChilkatException {
    print('Failed to load content file.');
    return;
  }

  // Begin building the TimeStampData.  
  // We'll build as XML and then convert to ASN.1
  final xml = CkXml();
  xml.tag = 'sequence';
  xml.updateChildContent('oid', '1.2.840.113549.1.9.16.1.31');
  xml.updateAttrAt('contextSpecific', true, 'tag', '0');
  xml.updateAttrAt('contextSpecific', true, 'constructed', '1');
  xml.updateChildContent('contextSpecific|sequence|int', '01');
  xml.updateChildContent('contextSpecific|sequence|octets', bdContent.getEncoded('base64'));
  xml.updateAttrAt('contextSpecific|sequence|contextSpecific', true, 'tag', '0');
  xml.updateAttrAt('contextSpecific|sequence|contextSpecific', true, 'constructed', '1');

  final xContext = xml.getChildWithTag('contextSpecific|sequence|contextSpecific');
  xContext.addChildTree(xmlTsr);

  // Convert the XML to ASN.1
  final tsd = CkAsn();
  tsd.loadAsnXml(xml.getXml());

  // Write the timestamped data to a file.
  tsd.writeBinaryDer('qa_output/sample.tsd');

  // Alternatively, get the tsd ASN.1 as base64..
  final tsdBase64 = tsd.getEncodedDer('base64_mime');
  print(tsdBase64);
}