(MFC) 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>

Chilkat C/C++ Library Downloads MS Visual C/C++ Libs

See Also: Using MFC CString in Chilkat

#include <CkGlobal.h>
#include <CkPem.h>
#include <CkAsn.h>
#include <CkXml.h>

void ChilkatSample(void)
    {
    CkString strOut;

    //  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.
    CkGlobal chilkatGlob;
    bool success = chilkatGlob.UnlockBundle("Anything for 30-day trial.");
    if (success != true) {
        strOut.append(chilkatGlob.lastErrorText());
        strOut.append("\r\n");
        SetDlgItemText(IDC_EDIT1,strOut.getUnicode());
        return;
    }

    CkPem pem;

    //  Load the PEM file.  The password is ignored because it is not an encrypted PEM.
    const char *password = "notRequired";
    success = pem.LoadPemFile("qa_data/asn/sampleCsr.pem",password);

    //  Get the CSR in base64 format:
    const char *itemType = "csr";
    const char *itemSubType = "";
    const char *encoding = "base64";
    int index = 0;
    const char *csrBase64 = pem.getEncodedItem(itemType,itemSubType,encoding,index);

    //  Load the CSR base64 string into the ASN object
    CkAsn asnRoot;

    success = asnRoot.LoadEncoded(csrBase64,"base64");
    if (success != true) {
        strOut.append(asnRoot.lastErrorText());
        strOut.append("\r\n");
        SetDlgItemText(IDC_EDIT1,strOut.getUnicode());
        return;
    }

    //  Get the ASN.1 in (Chilkat's) XML format:
    const char *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:
    CkXml xmlObj;
    success = xmlObj.LoadXml(asnXml);
    asnXml = xmlObj.getXml();

    strOut.append(asnXml);
    strOut.append("\r\n");


    SetDlgItemText(IDC_EDIT1,strOut.getUnicode());

    }