Using CAPICOM and .NET to envelope email.

From: Michael Marr (michael_at_marrconsulting.com)
Date: 08/31/05 

Date: 30 Aug 2005 16:23:32 -0700

Hello,

I'm using CAPICOM and .NET to envelope an e-mail. When I receive the
e-mail, I see that it is encrypted, but the body of the e-mail is empty
when I open it. I've been working on the issue for a couple days, so
any help would be greatly appreciated. Here's the code I'm using.

Thanks,
Michael...

-----------------------------------------------------------

using System;
using System.IO;
using CAPICOM;
using CDO;
using System.Runtime.InteropServices;

namespace test
{
  class EmailTest
  {
    [STAThread]
    static void Main(string[] args)
    {
      try
      {
        EmailTest me = new EmailTest();
        CAPICOM.Certificate signerCert = null;
        CAPICOM.Certificate recieverCert = null;
        CAPICOM.Store store = null;
        CAPICOM.Certificates certs = null;
        CDO.IMessage message = new MessageClass();
        CDO.IMessage secondMsg = new MessageClass();
        CDO.Configuration mailerConfig = new
CDO.ConfigurationClass();

        //
        // Setup mailer configuration.
        //

mailerConfig.Fields["http://schemas.microsoft.com/cdo/configuration/smtpserver"].Value
= "localhost";

mailerConfig.Fields["http://schemas.microsoft.com/cdo/configuration/smtpserverport"].Value
= "25";
        mailerConfig.Fields.Update();

        //
        // Retrieve certificates from certificate store.
        //
        store = new StoreClass();
        store.Open(CAPICOM_STORE_LOCATION.CAPICOM_CURRENT_USER_STORE,
"AddressBook", CAPICOM_STORE_OPEN_MODE.CAPICOM_STORE_OPEN_EXISTING_ONLY
| CAPICOM_STORE_OPEN_MODE.CAPICOM_STORE_OPEN_READ_ONLY);
        certs = (Certificates)store.Certificates;
        certs =
(Certificates)certs.Find(CAPICOM_CERTIFICATE_FIND_TYPE.CAPICOM_CERTIFICATE_FIND_SUBJECT_NAME,
"foo@domain.com", false);
        if(0 != certs.Count)
        {
          recieverCert = (Certificate)certs[1];
        }
        store.Open(CAPICOM_STORE_LOCATION.CAPICOM_CURRENT_USER_STORE,
"My", CAPICOM_STORE_OPEN_MODE.CAPICOM_STORE_OPEN_EXISTING_ONLY |
CAPICOM_STORE_OPEN_MODE.CAPICOM_STORE_OPEN_READ_ONLY);
        certs = (Certificates)store.Certificates;
        certs =
(Certificates)certs.Find(CAPICOM_CERTIFICATE_FIND_TYPE.CAPICOM_CERTIFICATE_FIND_SUBJECT_NAME,
"bar@domain.com", false);
        if(0 != certs.Count)
        {
          signerCert = (Certificate)certs[1];
        }

        //
        // Setup message...
        //
        message.To =
recieverCert.GetInfo(CAPICOM.CAPICOM_CERT_INFO_TYPE.CAPICOM_CERT_INFO_SUBJECT_EMAIL_NAME);
        message.From =
signerCert.GetInfo(CAPICOM.CAPICOM_CERT_INFO_TYPE.CAPICOM_CERT_INFO_SUBJECT_EMAIL_NAME);
        message.Subject = "Test Message " + DateTime.Now.ToString();
        message.HTMLBody = "<html><body>Test 123</body></html>";

        secondMsg = me.EnvelopeMessage(message, recieverCert);
        secondMsg.Configuration = mailerConfig;
        secondMsg.Send();

    }
      catch(Exception e)
      {
        Console.WriteLine(e.ToString());
      }
    }

    private CDO.IMessage EnvelopeMessage(CDO.IMessage message,
Certificate cert)
    {
      CDO.IMessage secureMsg = new CDO.MessageClass();
      CDO.IBodyPart bodyPart = null;
      CAPICOM.EnvelopedData envData = new
CAPICOM.EnvelopedDataClass();
      string content = String.Empty;
      string encryptedData = String.Empty;

      //
      // Copy message into new object.
      //
      secureMsg.DataSource.OpenObject(message, "IMessage");

      //
      // Configure header inforamtion.
      //
      bodyPart = secureMsg.BodyPart;
      bodyPart.ContentMediaType =
"application/pkcs7-mime;smime-type=enveloped-data;name=smime.p7m;";
      bodyPart.ContentTransferEncoding = "base64";

bodyPart.Fields["urn:schemas:mailheader:content-disposition"].Value =
"attachment;filename=smime.p7m";
      bodyPart.Fields.Update();

      //
      // Add the recipient certificate and encrypt the bodypart from
the original message.
      //
      envData.Recipients.Add(cert);
      ADODB.Stream tmpStream = message.BodyPart.GetStream();
      content = tmpStream.ReadText(tmpStream.Size);
      envData.Content = content;
      encryptedData =
envData.Encrypt(CAPICOM.CAPICOM_ENCODING_TYPE.CAPICOM_ENCODE_BASE64);

      //
      // Get stream handle and copy the encrypted data into the secure
message.
      //
      ADODB.Stream stream =
secureMsg.BodyPart.GetDecodedContentStream();
      stream.Type = ADODB.StreamTypeEnum.adTypeBinary;

      byte[] byteData = Convert.FromBase64String(encryptedData);

      stream.Write(byteData);
      stream.Flush();
      stream.Close();

      return secureMsg;
    }
  }
}

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