VB.NET

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.

VB.NET

Dim success As Boolean = False

Dim cert As New Chilkat.Cert

success = cert.LoadFromFile("qa_data/certs/test_haswdt.cer")
If (success <> True) Then
    Debug.WriteLine(cert.LastErrorText)
    Exit Sub
End If


' Get the Authority Information Access extension, which is at OID 1.3.6.1.5.5.7.1.1
Dim extensionXmlStr As String = cert.GetExtensionAsXml("1.3.6.1.5.5.7.1.1")
If (cert.LastMethodSuccess = False) Then
    Debug.WriteLine("Certificate does not have the AuthInfoAccess extension.")
    Exit Sub
End If


Dim xml As New Chilkat.Xml
xml.LoadXml(extensionXmlStr)

' See what we have..
Debug.WriteLine(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:

Dim sbOcsp As New Chilkat.StringBuilder
success = xml.GetChildContentSb("/C/oid,1.3.6.1.5.5.7.48.1|++",sbOcsp)
If (success = True) Then
    sbOcsp.Decode("base64","utf-8")
    Debug.WriteLine("1.3.6.1.5.5.7.48.1:  " & sbOcsp.GetAsString())
End If


Dim sbIssuer As New Chilkat.StringBuilder
success = xml.GetChildContentSb("/C/oid,1.3.6.1.5.5.7.48.2|++",sbIssuer)
If (success = True) Then
    sbIssuer.Decode("base64","utf-8")
    Debug.WriteLine("1.3.6.1.5.5.7.48.2:  " & sbIssuer.GetAsString())
End If


' 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".