(Excel) Load PEM ASN.1 and Convert to XML

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>

Download Excel Class Modules Chilkat Excel Class Modules

'  Starting in v9.5.0.49, all Chilkat classes can be unlocked at once at the beginning of a program
'  by calling UnlockBundle.  It requires a Bundle unlock code.
Dim chilkatGlob As Chilkat.CkGlobal
Set chilkatGlob = Chilkat.NewCkGlobal

success = chilkatGlob.UnlockBundle("Anything for 30-day trial.")
If (success <> True) Then
    Debug.Print chilkatGlob.LastErrorText
    Exit Sub
End If

Dim pem As Chilkat.Pem
Set pem = Chilkat.NewPem

'  Load the PEM file.  The password is ignored because it is not an encrypted PEM.

password = "notRequired"
success = pem.LoadPemFile("qa_data/asn/sampleCsr.pem",password)

'  Get the CSR in base64 format:

itemType = "csr"

itemSubType = ""

encoding = "base64"

index = 0

csrBase64 = pem.GetEncodedItem(itemType,itemSubType,encoding,index)

'  Load the CSR base64 string into the ASN object
Dim asnRoot As Chilkat.Asn
Set asnRoot = Chilkat.NewAsn

success = asnRoot.LoadEncoded(csrBase64,"base64")
If (success <> True) Then
    Debug.Print asnRoot.LastErrorText
    Exit Sub
End If

'  Get the ASN.1 in (Chilkat's) XML format:

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:
Dim xmlObj As Chilkat.Xml
Set xmlObj = Chilkat.NewXml
success = xmlObj.LoadXml(asnXml)
asnXml = xmlObj.GetXml()

Debug.Print asnXml