Create S/MIME Detached Signature with PFX

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How to use a PFX to create a signed S/MIME message.

Chilkat.Mime mime = new Chilkat.Mime();

bool success;
success = mime.UnlockComponent("Anything for 30-day trial");
if (success == false) {
    MessageBox.Show("Failed to unlock component");
    return;
}

mime.AddHeaderField("Subject","This is a test");
mime.AddHeaderField("Abc","123");

mime.SetBodyFromPlainText("This is the body");

Chilkat.CertStore certStore = new Chilkat.CertStore();

string password;
password = "myPassword";
success = certStore.LoadPfxFile("chilkat.pfx",password);
if (success == false) {
    MessageBox.Show(certStore.LastErrorText);
    return;
}

Chilkat.Cert cert;
cert = certStore.FindCertBySubjectCN("Chilkat Software, Inc.");
if (cert == null ) {
    MessageBox.Show("Failed to find certificate!");
    return;
}

//  Display the full distinguished name of the cert.
textBox1.Text += cert.SubjectDN + "\r\n";
textBox1.Refresh();

success = mime.AddDetachedSignature(cert);
if (success == false) {
    MessageBox.Show(mime.LastErrorText);
    return;
}

textBox1.Text += mime.GetMime() + "\r\n";
textBox1.Refresh();