Dart

Get Certificate Authority Information Access

See more Certificates Examples

Demonstrates how to get a certificate's Authority Information Access extension data (if it exists).

Note: This example requires Chilkat v9.5.0.76 or greater.

Dart

import 'package:chilkat/chilkat.dart';

void main() {
  final cert = CkCert();

  try {
    cert.loadFromFile('qa_data/certs/test_haswdt.cer');
  } on ChilkatException catch (e) {
    print(e.lastErrorText);
    return;
  }

  // Get the Authority Information Access extension, which is at OID 1.3.6.1.5.5.7.1.1
  final String extensionXmlStr;
  try {
    extensionXmlStr = cert.getExtensionAsXml('1.3.6.1.5.5.7.1.1');
  } on ChilkatException {
    print('Certificate does not have the AuthInfoAccess extension.');
    return;
  }

  final xml = CkXml();
  xml.loadXml(extensionXmlStr);

  // See what we have..
  print(xml.getXml());

  // We should get XML like this:

  // <?xml version="1.0" encoding="utf-8" ?>
  // <sequence>
  //     <sequence>
  //         <oid>1.3.6.1.5.5.7.48.2</oid>
  //         <contextSpecific tag="6" constructed="0">aHR0cDovL2NydC5jb21vZG9jYS5jb20vQ09NT0RPUlNBQ2xpZW50QXV0aGVudGljYXRpb25hbmRTZWN1
  // cmVFbWFpbENBLmNydA==</contextSpecific>
  //     </sequence>
  //     <sequence>
  //         <oid>1.3.6.1.5.5.7.48.1</oid>
  //         <contextSpecific tag="6" constructed="0">aHR0cDovL29jc3AuY29tb2RvY2EuY29t</contextSpecific>
  //     </sequence>
  // </sequence>

  // Typically, a certificate AIA(Authority Information access) contains 2 parts:
  // 
  //     On-line Certificate Status Protocol (1.3.6.1.5.5.7.48.1)
  //     Certification Authority Issuer (1.3.6.1.5.5.7.48.2)
  // 
  // The base64 content for each OID (in this case) is just a string.  
  // The data can be accessed and decoded like this:

  final sbOcsp = CkStringBuilder();
  try {
    xml.getChildContentSb('/C/oid,1.3.6.1.5.5.7.48.1|++', sbOcsp);
    sbOcsp.decode('base64', 'utf-8');
    print('1.3.6.1.5.5.7.48.1:  ${sbOcsp.getAsString()}');
  } on ChilkatException {
    // xml.getChildContentSb() failed; continue anyway.
  }

  final sbIssuer = CkStringBuilder();
  try {
    xml.getChildContentSb('/C/oid,1.3.6.1.5.5.7.48.2|++', sbIssuer);
    sbIssuer.decode('base64', 'utf-8');
    print('1.3.6.1.5.5.7.48.2:  ${sbIssuer.getAsString()}');
  } on ChilkatException {
    // xml.getChildContentSb() failed; continue anyway.
  }

  // The output looks like this:

  // 1.3.6.1.5.5.7.48.1:  http://ocsp.comodoca.com
  // 1.3.6.1.5.5.7.48.2:  http://crt.comodoca.com/COMODORSAClientAuthenticationandSecureEmailCA.crt

  // -------------------------------------------------------------------------------
  // Note: The Chilkat path passed to GetChildContentSb is composed of two commands:
  // The first command is "/C/oid,1.3.6.1.5.5.7.48.1".   It says "traverse the XML tree from the caller
  // node and stop at the 1st node having tag = "oid" and content = "1.3.6.1.5.5.7.48.1".
  // The "|" char separates the 1st command from the 2nd.
  // The 2nd command is "++" and says "move to the next sibling".
}