(C#) Add S/MIME Signature using PFX

Add a digital signature to a MIME message using the certificate + private key from a PFX file.

Download: Chilkat .NET Assemblies

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

bool success;
success = mime.UnlockComponent("Anything for 30-day trial");
if (success == false) {
    textBox1.Text += mime.LastErrorText + "\r\n";
    return;
}

//  Load a PFX file into a certificate object.
Chilkat.Cert cert = new Chilkat.Cert();
string pfxFilepath;
pfxFilepath = "pfxFiles/something.pfx";
string pfxPassword;
pfxPassword = "secret";
success = cert.LoadPfxFile(pfxFilepath,pfxPassword);
if (success == false) {
    textBox1.Text += cert.LastErrorText + "\r\n";
    return;
}

mime.SetBodyFromPlainText("This is the plain-text MIME body.");

mime.Charset = "utf-8";
mime.Encoding = "quoted-printable";

//  Sign the MIME (adds a PKCS7 detached signature)
success = mime.AddDetachedSignature(cert);
if (success == false) {
    textBox1.Text += mime.LastErrorText + "\r\n";
    return;
}

//  Save the S/MIME to a file.
success = mime.SaveMime("/temp/signedMime.txt");
if (success == false) {
    textBox1.Text += mime.LastErrorText + "\r\n";
    return;
}

MessageBox.Show("success!");