(C#) Create CMS (PKCS7) Detached MIME Signature

Demonstrates how to add a CMS detached signature to MIME.

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// This example assumes the Chilkat API to have been previously unlocked.
// See Global Unlock Sample for sample code.

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

// Load a certificate w/ private key for signing.
Chilkat.Cert cert = new Chilkat.Cert();
bool success = cert.LoadPfxFile("qa_data/pfx/ecc256_12345.p12","12345");
if (success != true) {
    Debug.WriteLine(cert.LastErrorText);
    return;
}

Debug.WriteLine("Cert: " + cert.SubjectDN);

// Create a simple MIME message to be signed:
mime.AddHeaderField("Subject","This is a test");
mime.AddHeaderField("MyCustomHeader","abc123");
mime.ContentType = "text/plain";
mime.SetBody("This is a plain-text body.");

// Examine the MIME prior to signing:
Debug.WriteLine("--- MIME prior to signing ---");
Debug.WriteLine(mime.GetMime());

// The MIME prior to signing looks like this:

// Subject: This is a test
// MyCustomHeader: abc123
// Content-Type: text/plain; format=flowed
// 
// This is a plain-text body.

// Use SHA256 as the hash algorithm in the CMS signature.
mime.SigningHashAlg = "SHA256";

// Add a detached signature:
success = mime.AddDetachedSignature(cert);
if (success == false) {
    Debug.WriteLine(mime.LastErrorText);
    return;
}

// Examine the MIME with detached signature:
Debug.WriteLine("--- MIME with detached signature ---");
Debug.WriteLine(mime.GetMime());

// Content-Type: multipart/signed; boundary="----=_NextPart_6e3_c655_9641494d.b4f00501";
//  protocol="application/x-pkcs7-signature";
//  micalg=sha256
// 
// ------=_NextPart_6e3_c655_9641494d.b4f00501
// Subject: This is a test
// MyCustomHeader: abc123
// Content-Type: text/plain; format=flowed
// 
// This is a plain-text body.
// ------=_NextPart_6e3_c655_9641494d.b4f00501
// Content-Transfer-Encoding: base64
// Content-Type: application/x-pkcs7-signature; name="smime.p7s"
// Content-Disposition: attachment; filename="smime.p7s"
// 
// MIID7AYJKoZIhvcNAQcCoIID3TCCA9kCAQExDzANBglghkgBZQMEAgEFADALBgkqhkiG9w0BBwGg
// ggJxMIICbTCCAhOgAwIBAgIJAJuS2kgOoyr+MAkGByqGSM49BAEwWzELMAkGA1UEBhMCQVUxEzAR
// BgNVBAgTClNvbWUtU3RhdGUxITAfBgNVBAoTGEludGVybmV0IFdpZGdpdHMgUHR5IEx0ZDEUMBIG
// A1UEAxMLZWNjMjU2LXRlc3QwHhcNMTYwODIzMTU0OTM5WhcNNDQwMTA4MTU0OTM5WjBbMQswCQYD
// VQQGEwJBVTETMBEGA1UECBMKU29tZS1TdGF0ZTEhMB8GA1UEChMYSW50ZXJuZXQgV2lkZ2l0cyBQ
// dHkgTHRkMRQwEgYDVQQDEwtlY2MyNTYtdGVzdDBZMBMGByqGSM49AgEGCCqGSM49AwEHA0IABARy
// Hd86A7+qQ4DlIfKynZaFGdGLpkU3GlQwqaVD6GIJg3QIDhaWEksYtZ9OWjNHn9a6+i/P9o5/NrdI
// SP0VWDWjgcAwgb0wHQYDVR0OBBYEFGmd2DfK4c3VBTVn8ebKH2BTmRicMIGNBgNVHSMEgYUwgYKA
// FGmd2DfK4c3VBTVn8ebKH2BTmRicoV+kXTBbMQswCQYDVQQGEwJBVTETMBEGA1UECBMKU29tZS1T
// dGF0ZTEhMB8GA1UEChMYSW50ZXJuZXQgV2lkZ2l0cyBQdHkgTHRkMRQwEgYDVQQDEwtlY2MyNTYt
// dGVzdIIJAJuS2kgOoyr+MAwGA1UdEwQFMAMBAf8wCQYHKoZIzj0EAQNJADBGAiEAhuiwGy0lZKtK
// LA13Ffc8AMTK7NsePPSfs0clXlZUR78CIQDXsJXpYsJ7tlTeockrK+6099sG/gGFTRPiQYU8juyf
// LzGCAT8wggE7AgEBMGgwWzELMAkGA1UEBhMCQVUxEzARBgNVBAgTClNvbWUtU3RhdGUxITAfBgNV
// BAoTGEludGVybmV0IFdpZGdpdHMgUHR5IEx0ZDEUMBIGA1UEAxMLZWNjMjU2LXRlc3QCCQCbktpI
// DqMq/jANBglghkgBZQMEAgEFAKBpMBgGCSqGSIb3DQEJAzELBgkqhkiG9w0BBwEwHAYJKoZIhvcN
// AQkFMQ8XDTIyMDUwODE0MzM1NFowLwYJKoZIhvcNAQkEMSIEIMvNpYuymLvF68aFFe+l3NEQTdkB
// 7T8U6/j+Y5FgDlIUMAoGCCqGSM49BAMCBEYwRAIgQ6migEn3Le9ciIVUP/qc2JZAJZWjpulJXY9Q
// IZJ3XK0CIGZwpLOgiv7ES8958hqT9a/q7aPc1xmkaZHtsat/k+Ki
// 
// ------=_NextPart_6e3_c655_9641494d.b4f00501--