Dart

Load PEM ASN.1 and Convert to XML

See more ASN.1 Examples

Loads a CSR (Certificate Signing Request) from PEM and converts the ASN.1 to XML format. The purpose of this example is to compare the ASN.1 format with the corresponding XML. One means for accessing a particular piece of information within any ASN.1 document is to convert to XML, and then use any XML API to extract the required data.

The PEM used in this example may be downloaded here: Sample CSR PEM

It contains ASN.1 with this format:

After converting, the XML looks like this:

<?xml version="1.0" encoding="utf-8" ?>
<sequence>
    <sequence>
        <int>00</int>
        <sequence>
            <set>
                <sequence>
                    <oid>2.5.4.6</oid>
                    <printable>US</printable>
                </sequence>
            </set>
            <set>
                <sequence>
                    <oid>2.5.4.8</oid>
                    <utf8>Utah</utf8>
                </sequence>
            </set>
            <set>
                <sequence>
                    <oid>2.5.4.7</oid>
                    <utf8>Lindon</utf8>
                </sequence>
            </set>
            <set>
                <sequence>
                    <oid>2.5.4.10</oid>
                    <utf8>DigiCert Inc.</utf8>
                </sequence>
            </set>
            <set>
                <sequence>
                    <oid>2.5.4.11</oid>
                    <utf8>DigiCert</utf8>
                </sequence>
            </set>
            <set>
                <sequence>
                    <oid>2.5.4.3</oid>
                    <utf8>example.digicert.com</utf8>
                </sequence>
            </set>
        </sequence>
        <sequence>
            <sequence>
                <oid>1.2.840.113549.1.1.1</oid>
                <null />
            </sequence>
            <bits n="2160">3082010A0282010... </bits>
        </sequence>
        <contextSpecific tag="0" constructed="1" />
    </sequence>
    <sequence>
        <oid>1.2.840.113549.1.1.5</oid>
        <null />
    </sequence>
    <bits n="2048">1D2472B15C7129850E6...  </bits>
</sequence>

Dart

import 'package:chilkat/chilkat.dart';

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

  final pem = CkPem();

  // Load the PEM file.  The password is ignored because it is not an encrypted PEM.
  final password = 'notRequired';
  pem.loadPemFile('qa_data/asn/sampleCsr.pem', password);

  // Get the CSR in base64 format:
  final itemType = 'csr';
  final itemSubType = '';
  final encoding = 'base64';
  final index = 0;
  final csrBase64 = pem.getEncodedItem(itemType, itemSubType, encoding, index);

  // Load the CSR base64 string into the ASN object
  final asnRoot = CkAsn();

  try {
    asnRoot.loadEncoded(csrBase64, 'base64');
  } on ChilkatException catch (e) {
    print(e.lastErrorText);
    return;
  }

  // Get the ASN.1 in (Chilkat's) XML format:
  var asnXml = asnRoot.asnToXml();

  // The XML returned by AsnToXml is one long difficult-to-read string 
  // with no linebreaks.  It is meant to be compact.
  // To get the XML in pretty, human-readable, indented form,
  // load into the Chilkat XML object an then retrieve:
  final xmlObj = CkXml();
  xmlObj.loadXml(asnXml);
  asnXml = xmlObj.getXml();

  print(asnXml);
}