(C# UWP/WinRT) Create PKCS7 Attached/Opaque Signature (S/MIME)

Create an S/MIME message with a PKCS7 attached/opaque signature.

Chilkat Universal Windows Platform (UWP) / WinRT Downloads Chilkat for the Universal Windows Platform (UWP)

// This example requires 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.
// There are many ways of getting a certificate object:
// from a pfx file, from .cer and private-key files, from the
// Windows registry-based certificate stores, etc.
// Load a PFX file into a certificate object.
Chilkat.Cert cert = new Chilkat.Cert();
string pfxFilepath = "pfxFiles/something.pfx";
string pfxPassword = "secret";
bool success = cert.LoadPfxFile(pfxFilepath,pfxPassword);
if (success == false) {
    Debug.WriteLine(cert.LastErrorText);
    return;
}

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

// -------------------------------------------------------------------------------

// The default hash algorithm used in the signing process is "SHA1".
// To change it, set the SigningHashAlg property:
mime.SigningHashAlg = "SHA256";

// Convert the MIME to PKCS7 signed-data.
success = mime.ConvertToSigned(cert);
if (success == false) {
    Debug.WriteLine(mime.LastErrorText);
    return;
}

// Examine the signed MIME
Debug.WriteLine("--- MIME converted to PKCS7 signed-data ---");
Debug.WriteLine(mime.GetMime());

// The MIME after signing looks like this:
// -------------------------------------------------------------------------------

// Subject: This is a test
// MyCustomHeader: abc123
// Content-Disposition: attachment; filename="smime.p7m"
// Content-Transfer-Encoding: base64
// Content-Type: application/x-pkcs7-mime;
//  name="smime.p7m"; smime-type="signed-data"
// 
// MIIObAYJKoZIhvcNAQcCoIIOXTCCDlkCAQExDzANBglghkgBZQMEAgEFADB2BgkqhkiG9w0BBwGg
// aQRnU3ViamVjdDogVGhpcyBpcyBhIHRlc3QNCk15Q3VzdG9tSGVhZGVyOiBhYmMxMjMNCkNvbnRl
// bnQtVHlwZTogdGV4dC9wbGFpbg0KDQpUaGlzIGlzIGEgcGxhaW4tdGV4dCBib2R5LqCCCaAwggRm
// MIIDTqADAgECAhBEvgyLUAAktBHTNi3gs18bMA0GCSqGSIb3DQEBBQUAMIGVMQswCQYDVQQGEwJV
// UzELMAkGA1UECBMCVVQxFzAVBgNVBAcTDlNhbHQgTGFrZSBDaXR5MR4wHAYDVQQKExVUaGUgVVNF
// UlRSVVNUIE5ldHdvcmsxITAfBgNVBAsTGGh0dHA6Ly93d3cudXNlcnRydXN0LmNvbTEdMBsGA1UE
// AxMUVVROLVVTRVJGaXJzdC1PYmplY3QwHhcNOTkwNzA5MTgzMTIwWhcNMTkwNzA5MTg0MDM2WjCB
// lTELMAkGA1UEBhMCVVMxCzAJBgNVBAgTAlVUMRcwFQYDVQQHEw5TYWx0IExha2UgQ2l0eTEeMBwG
// A1UEChMVVGhlIFVTRVJUUlVTVCBOZXR3b3JrMSEwHwYDVQQLExhodHRwOi8vd3d3LnVzZXJ0cnVz
// dC5jb20xHTAbBgNVBAMTFFVUTi1VU0VSRmlyc3QtT2JqZWN0MIIBIjANBgkqhkiG9w0BAQEFAAOC
// AQ8AMIIBCgKCAQEAzqqBP6OjYXiqMQBVlRGeJw8fHN86m4JoMMBKYR3xLw76vnn3pSPvVVGWhM3b
// 47luPjHYCiBnx/TZv5TrRwQ+As4qol2HBAn2MJ0Yipeyqhz8QdKhNsv7PZG659lwNfrk55DDm6Ob
// 0zz1Epl3sbcJ4GjmHLjzlGOIamr+C3bJvvQi5Ge5qxped8GFB90NbL/uBsd3akGepw/X++6UF7f8
// hb6kq8QcMd3XttHk8O/fFo+yUpPXodSJoQcuv+EBEkIeGuHYlTTbZHko/7ouEcLl6FuSSPtHC8Js
// 2q0yg0HzpeVBcP1lkG36+lHE+b2WKxkELNNtp9zwf2+DZeJqq4eGdQIDAQABo4GvMIGsMAsGA1Ud
// DwQEAwIBxjAPBgNVHRMBAf8EBTADAQH/MB0GA1UdDgQWBBTa7WR0FJwUPKvdmam9WyhNizzJ2DBC
// BgNVHR8EOzA5MDegNaAzhjFodHRwOi8vY3JsLnVzZXJ0cnVzdC5jb20vVVROLVVTRVJGaXJzdC1P
// YmplY3QuY3JsMCkGA1UdJQQiMCAGCCsGAQUFBwMDBggrBgEFBQcDCAYKKwYBBAGCNwoDBDANBgkq
// hkiG9w0BAQUFAAOCAQEACB9SsTdEeNv9zrnalZaYqlVkgLVaQN0hpcXB818sTMhHWmnq6PA1NfTQ
// JfPIpqSHSr0bsXMIvdTDyrY1u1mGdzHNp4AUrhPv/LFI+WslJS1RtixtRcGYyIpWXT7uQ04+ayeO
// 0DpLhQtf0+1qp3XL0VqHLzl1E1pysAKBn77wD4RUIGJsadThTcYNmUMBDRKWjHidv1CisUSqas8X
// es9vD9T4JFVf8DQWSWY+UEbJY3E4MWK4YrnzU61stSuiEqoZTwnaXueTxo4UCP7wMIAYoIaFTch9
// 14sD/m7V950WrJIsoCPlnJFSH5TfF5Rzw7PBwXEFIAB4vRNSHag+zQAfyDCCBTIwggQaoAMCAQIC
// EQDm/GiUo2tiCnVnsAEgJ0r7MA0GCSqGSIb3DQEBBQUAMIGVMQswCQYDVQQGEwJVUzELMAkGA1UE
// CBMCVVQxFzAVBgNVBAcTDlNhbHQgTGFrZSBDaXR5MR4wHAYDVQQKExVUaGUgVVNFUlRSVVNUIE5l
// dHdvcmsxITAfBgNVBAsTGGh0dHA6Ly93d3cudXNlcnRydXN0LmNvbTEdMBsGA1UEAxMUVVROLVVT
// RVJGaXJzdC1PYmplY3QwHhcNMDkxMDEyMDAwMDAwWhcNMTAxMDEyMjM1OTU5WjCBoDELMAkGA1UE
// BhMCVVMxDjAMBgNVBBEMBTYwMTg3MREwDwYDVQQIDAhJbGxpbm9pczEQMA4GA1UEBwwHV2hlYXRv
// bjEaMBgGA1UECQwRMTcxOSBFIEZvcmVzdCBBdmUxHzAdBgNVBAoMFkNoaWxrYXQgU29mdHdhcmUs
// IEluYy4xHzAdBgNVBAMMFkNoaWxrYXQgU29mdHdhcmUsIEluYy4wggEiMA0GCSqGSIb3DQEBAQUA
// A4IBDwAwggEKAoIBAQC5ueUJPjI74J5Yavc3JUCWHEMMd2C9T+4VDuUcN7vzYuIOjsyV1yhzAl8+
// uxzE+dhfcRK8qw9JbRV56Dzfyz5DqJH9x0rlbzkM24NeNZyM1kXIs2NHCJTYlYUqlVLZ2SXpiqru
// nnYEFScZho3knWoBYC4841sdUay70pqluo2Y1CBbx5t+zYPXit370hEGzKLNK6XRTevcVQQMvL/f
// d/gz241M8KBT8yvqTAjv6NJz9tHNUqhYO5mTT65nsIwKQ5/T8L+hsOHi4VM2QdVW6ZD9jrfPIfES
// yOyfXCx2l9oEHfB3gwgdYQ4Mq9hRG77mIc9H+pw1V0yMmQmEVs0LP6hvAgMBAAGjggFuMIIBajAf
// BgNVHSMEGDAWgBTa7WR0FJwUPKvdmam9WyhNizzJ2DAdBgNVHQ4EFgQUBMe/RfjpWAOjAMHml1qw
// DvPa4OowDgYDVR0PAQH/BAQDAgeAMAwGA1UdEwEB/wQCMAAwEwYDVR0lBAwwCgYIKwYBBQUHAwMw
// EQYJYIZIAYb4QgEBBAQDAgQQMEYGA1UdIAQ/MD0wOwYMKwYBBAGyMQECAQMCMCswKQYIKwYBBQUH
// AgEWHWh0dHBzOi8vc2VjdXJlLmNvbW9kby5uZXQvQ1BTMEIGA1UdHwQ7MDkwN6A1oDOGMWh0dHA6
// Ly9jcmwudXNlcnRydXN0LmNvbS9VVE4tVVNFUkZpcnN0LU9iamVjdC5jcmwwNAYIKwYBBQUHAQEE
// KDAmMCQGCCsGAQUFBzABhhhodHRwOi8vb2NzcC5jb21vZG9jYS5jb20wIAYDVR0RBBkwF4EVYWRt
// aW5AY2hpbGthdHNvZnQuY29tMA0GCSqGSIb3DQEBBQUAA4IBAQAP/2IpG75SHSFFqjHqvCXy0n0O
// MTQk2IexnIUBlF7wm0oZquXBG2GlOPd9IXNr7k3wf4G+nZ6rgit6slVT1VxZS8RzqhGT3ZRTa2ud
// dSqJyKxxrqdBJMY/WWaWVtCSU74AKAAm/ONwD1Zz39IZ2Mr8ApXn2LnZy4ZgI3hZnVR8I92/sppl
// +NKWr0iMBpcz2KEwXZ5lrS5/4qRFlY+LQgRBFnjoM9WDW1lGEqeHFQQ/dqyrNiRAp+l7OzPBS4aM
// nfxS+Yj/blpnuW41dVi9TJTXozRwiHzQ41FfrkJMD4JZULc539SK1EU1cYMl13x3JODHlng2IrjZ
// pCKrFCsSCP2BMYIEJTCCBCECAQEwgaswgZUxCzAJBgNVBAYTAlVTMQswCQYDVQQIEwJVVDEXMBUG
// A1UEBxMOU2FsdCBMYWtlIENpdHkxHjAcBgNVBAoTFVRoZSBVU0VSVFJVU1QgTmV0d29yazEhMB8G
// A1UECxMYaHR0cDovL3d3dy51c2VydHJ1c3QuY29tMR0wGwYDVQQDExRVVE4tVVNFUkZpcnN0LU9i
// amVjdAIRAOb8aJSja2IKdWewASAnSvswDQYJYIZIAWUDBAIBBQCgggJKMBgGCSqGSIb3DQEJAzEL
// BgkqhkiG9w0BBwEwHAYJKoZIhvcNAQkFMQ8XDTEwMDYzMDE0NTg0MFowLwYJKoZIhvcNAQkEMSIE
// ILEFXqrFbp/l0XOJyyjW1IJhjJxJaOhLUlZTc8VcabVMMF8GCSqGSIb3DQEJDzFSMFAwCwYJYIZI
// AWUDBAECMAoGCCqGSIb3DQMHMA4GCCqGSIb3DQMCAgIAgDANBggqhkiG9w0DAgIBQDAHBgUrDgMC
// BzANBggqhkiG9w0DAgIBKDCBvAYJKwYBBAGCNxAEMYGuMIGrMIGVMQswCQYDVQQGEwJVUzELMAkG
// A1UECBMCVVQxFzAVBgNVBAcTDlNhbHQgTGFrZSBDaXR5MR4wHAYDVQQKExVUaGUgVVNFUlRSVVNU
// IE5ldHdvcmsxITAfBgNVBAsTGGh0dHA6Ly93d3cudXNlcnRydXN0LmNvbTEdMBsGA1UEAxMUVVRO
// LVVTRVJGaXJzdC1PYmplY3QCEQDm/GiUo2tiCnVnsAEgJ0r7MIG+BgsqhkiG9w0BCRACCzGBrqCB
// qzCBlTELMAkGA1UEBhMCVVMxCzAJBgNVBAgTAlVUMRcwFQYDVQQHEw5TYWx0IExha2UgQ2l0eTEe
// MBwGA1UEChMVVGhlIFVTRVJUUlVTVCBOZXR3b3JrMSEwHwYDVQQLExhodHRwOi8vd3d3LnVzZXJ0
// cnVzdC5jb20xHTAbBgNVBAMTFFVUTi1VU0VSRmlyc3QtT2JqZWN0AhEA5vxolKNrYgp1Z7ABICdK
// +zANBgkqhkiG9w0BAQEFAASCAQBfYh75saVFNXRPOzXOemaoVIFz+OHSsQB1fqXbV+hjGkxuvWAT
// ldq32luVFFCz2gErWDT8eZ0yFVVwi16XyP7ptZeGU4cIGtrOozq78dziWwbNB021c3Dcw0vmH83m
// FrU8ZNXYhL2+Lu4PlgvSCxHtC9EKrsP0s3WvBk3nMgXhu4Nmvkl1pCAofhAXWs545TfFB3jLEgeR
// spbT6PhRR2lErXKF/Ga5NUyUqpw/Ba2YB3fFsbwiMyncmYicnUT2eYxxYBPtX9X6DQSKh3+iLNz0
// sx89fluXIoqWONjR/XyN8zYd6WtEqMMwY6HQPAblFEuMPHZIhC0h/hfGAVisKLmh
// 

// ------------------------------------------------------------------------------