(C) Get Certificate Distinguished Name in .NET Format

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Certificate distinguished names (DN's), in the real world, can be constructed in various ways. Some systems expect certain ways of doing things. This example demonstrates how to get a DN (or SimpleName) exactly as .NET would return it.

This example requires Chilkat v9.5.0.96.

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#include <C_CkCert.h>

void ChilkatSample(void)
    {
    HCkCert cert;
    BOOL success;
    const char *subjectDN;

    cert = CkCert_Create();

    success = CkCert_LoadFromFile(cert,"qa_data/certs/testCert.cer");
    if (success == FALSE) {
        printf("%s\n",CkCert_lastErrorText(cert));
        CkCert_Dispose(cert);
        return;
    }

    // In 99% of all cases, Chilkat already returns the Distinguished Name in the identical format as .NET.
    // 
    // In most cases, (internal to the certificate) the ASN.1 for the certificate's Subject 
    // contains a sesquence of OIDs and values, where each OID is the single item in a SET.
    // For example:

    // SEQUENCE (3 elem)
    //       SET (1 elem)
    //         SEQUENCE (2 elem)
    //           OBJECT IDENTIFIER 2.5.4.6 countryName (X.520 DN component)
    //           PrintableString FR
    //       SET (1 elem)
    //         SEQUENCE (2 elem)
    //           OBJECT IDENTIFIER 2.5.4.12 title (X.520 DN component)
    //           UTF8String Mdecin
    //       SET (3 elem)
    //         SEQUENCE (2 elem)
    //           OBJECT IDENTIFIER 2.5.4.42 givenName (X.520 DN component)
    //           UTF8String ALAIN
    //       SET (3 elem)
    //         SEQUENCE (2 elem)
    //           OBJECT IDENTIFIER 2.5.4.4 surname (X.520 DN component)
    //           UTF8String DUBOIS RPPS
    //       SET (3 elem)
    //         SEQUENCE (2 elem)
    //           OBJECT IDENTIFIER 2.5.4.3 commonName (X.520 DN component)
    //           UTF8String 389900098933

    // If we look at the DN, we get this:
    subjectDN = CkCert_subjectDN(cert);
    printf("%s\n",subjectDN);

    // Chilkat produces this:
    // C=FR, Title=Mdecin, G=ALAIN, SN=DUBOIS RPPS, CN=389900098933

    // However, if the certificate's internal ASN.1 groups several items in a single SET,
    // such as shown below, Microsoft .NET will produce a DN like this:
    // G=ALAIN + SN=DUBOIS RPPS + CN=389900098933, T=Mdecin, C=FR

    // Notice how the items in the SET are grouped with " + ".
    // Also notice the order is reverse, and "T" is used instead of using "Title.
    // These are all variations of how a DN might be formatted.
    // In practice, there is no correct way because what is needed depends on what is
    // required as input to whatever is receiving the DN.

    // SEQUENCE (3 elem)
    //       SET (1 elem)
    //         SEQUENCE (2 elem)
    //           OBJECT IDENTIFIER 2.5.4.6 countryName (X.520 DN component)
    //           PrintableString FR
    //       SET (1 elem)
    //         SEQUENCE (2 elem)
    //           OBJECT IDENTIFIER 2.5.4.12 title (X.520 DN component)
    //           UTF8String Mdecin
    //       SET (3 elem)
    //         SEQUENCE (2 elem)
    //           OBJECT IDENTIFIER 2.5.4.42 givenName (X.520 DN component)
    //           UTF8String ALAIN
    //         SEQUENCE (2 elem)
    //           OBJECT IDENTIFIER 2.5.4.4 surname (X.520 DN component)
    //           UTF8String DUBOIS RPPS
    //         SEQUENCE (2 elem)
    //           OBJECT IDENTIFIER 2.5.4.3 commonName (X.520 DN component)
    //           UTF8String 389900098933

    // To ensure Chilkat produces the same DN format as .NET, you can specify
    // the keyword "DotNetSimpleName" in the UncommonOptions.
    // For example:

    CkCert_putUncommonOptions(cert,"DotNetSimpleName");

    // If the above option is used (which was added in Chilkat v9.5.0.96), then Chilkat
    // will produce the DN in the same format as .NET

    subjectDN = CkCert_subjectDN(cert);
    printf("%s\n",subjectDN);

    // Now Chilkat produces this:
    // G=ALAIN + SN=DUBOIS RPPS + CN=389900098933, T=Mdecin, C=FR


    CkCert_Dispose(cert);

    }