MailModel HandlePgpMime(Outlook.MailItem mailItem, Outlook.Attachment encryptedMime, Outlook.Attachment sigMime, string sigHash = "sha1")
{
Logger.Trace("> HandlePgpMime");
CryptoContext context = null;
var cleartext = mailItem.Body;
// 1. Decrypt attachement
if (encryptedMime != null)
{
if (DecryptMime(mailItem, encryptedMime, ref context, ref cleartext))
{
return null;
}
}
// 2. Verify signature
Signature signature = null;
if (sigMime != null)
{
context = new CryptoContext(Passphrase);
signature = VerifySignature(mailItem, sigMime, sigHash, ref context);
}
if (context == null)
return null;
// Extract files from MIME data
MailModel mailModel = null;
var msg = new SharpMessage(cleartext);
string body = mailItem.Body;
if (mailItem.BodyFormat == Outlook.OlBodyFormat.olFormatPlain)
{
mailModel = new PlainMailModel
{
Body = msg.Body
};
}
else if (mailItem.BodyFormat == Outlook.OlBodyFormat.olFormatHTML)
{
if (!msg.Body.TrimStart().ToLower().StartsWith("<html"))
{
body = msg.Body;
body = System.Net.WebUtility.HtmlEncode(body);
body = body.Replace("\n", "<br />");
mailModel = new HtmlMailModel
{
Body = "<html><head></head><body>" + body + "</body></html>"
};
}
else
{
mailModel = new HtmlMailModel
{
Body = msg.Body
};
}
}
else
{
// May cause mail item not to open correctly
mailModel = new PlainMailModel
{
Body = msg.Body,
Signature = signature
};
}
foreach (SharpAttachment mimeAttachment in msg.Attachments)
{
mimeAttachment.Stream.Position = 0;
var fileName = mimeAttachment.Name;
var tempFile = Path.Combine(Path.GetTempPath(), fileName);
using (var fout = File.OpenWrite(tempFile))
{
mimeAttachment.Stream.CopyTo(fout);
}
if (fileName == "signature.asc")
{
var detachedsig = File.ReadAllText(tempFile);
var clearsig = CreateClearSignatureFromDetachedSignature(mailItem, sigHash, detachedsig);
var crypto = new PgpCrypto(context);
signature = VerifyClearSignature(ref context, crypto, clearsig);
}
mailModel.Attachments.Add(new Attachment
{
TempFile = tempFile,
AttachmentType = Outlook.OlAttachmentType.olByValue,
FileName = fileName
});
}
mailModel.Body = mailModel.Body;
mailModel.Signature = signature;
return mailModel;
}
public MailModel DecryptEmail(Outlook.MailItem mailItem)
{
if (mailItem.Body == null || Regex.IsMatch(mailItem.Body, PgpEncryptedHeader) == false)
{
return HandleMailWithoutPgpBody(mailItem);
}
MailModel mailModel;
// Sometimes messages could contain multiple message blocks. In that case just use the
// very first one.
var firstPgpBlock = GetFirstPgpBlock(mailItem);
var encoding = GetEncoding(firstPgpBlock);
CryptoContext context;
var cleardata = DecryptAndVerify(mailItem.To, Encoding.ASCII.GetBytes(firstPgpBlock), out context);
if (cleardata == null)
return null;
if (mailItem.BodyFormat == Outlook.OlBodyFormat.olFormatHTML)
{
// Don't HMTL encode or we will encode emails already in HTML format.
// Office has a safe html module they use to prevent security issues.
// Not encoding here should be no worse then reading a standard HTML
// email.
var html = encoding.GetString(cleardata);
html = html.Replace("\n", "<br/>");
html = "<html><body>" + html + "</body></html>";
mailModel = new HtmlMailModel
{
Body = html
};
}
else
{
var mailText = encoding.GetString(cleardata);
mailModel = new PlainMailModel
{
Body = mailText
};
}
// Decrypt all attachments
var mailAttachments = CreateAttachmentListFromMailItem(mailItem);
var attachments = new List<Attachment>();
foreach (var attachment in mailAttachments)
{
var tempAttachment = new Attachment();
// content id
if (attachment.FileName.StartsWith("Attachment") && attachment.FileName.EndsWith(".pgp"))
{
var property = attachment.PropertyAccessor.GetProperty("http://schemas.microsoft.com/mapi/proptag/0x3712001F");
tempAttachment.FileName = property.ToString();
if (tempAttachment.FileName.Contains('@'))
{
tempAttachment.FileName = tempAttachment.FileName.Substring(0, tempAttachment.FileName.IndexOf('@'));
}
tempAttachment.TempFile = Path.GetTempPath();
tempAttachment.AttachmentType = attachment.Type;
tempAttachment.TempFile = Path.Combine(tempAttachment.TempFile, tempAttachment.FileName);
attachment.SaveAsFile(tempAttachment.TempFile);
TryDecryptAndAddAttachment(mailItem, tempAttachment, attachments);
}
//else if (attachment.FileName == "PGPexch.htm.pgp")
//{
// // This is the HTML email message.
// var TempFile = Path.GetTempFileName();
// attachment.SaveAsFile(TempFile);
// // Decrypt file
// var cyphertext = File.ReadAllBytes(TempFile);
// File.Delete(TempFile);
// try
// {
// var plaintext = DecryptAndVerify(mailItem.To, cyphertext);
// mailItem.BodyFormat = Outlook.OlBodyFormat.olFormatHTML;
// mailItem.HTMLBody = _encoding.GetString(plaintext);
// }
// catch
// {
// // Odd!
// }
//}
else
{
tempAttachment.FileName = Regex.Replace(attachment.FileName, EncryptionExtension, "");
tempAttachment.DisplayName = Regex.Replace(attachment.DisplayName, EncryptionExtension, ""); ;
tempAttachment.TempFile = Path.GetTempPath();
tempAttachment.AttachmentType = attachment.Type;
tempAttachment.TempFile = Path.Combine(tempAttachment.TempFile, tempAttachment.FileName);
attachment.SaveAsFile(tempAttachment.TempFile);
TryDecryptAndAddAttachment(mailItem, tempAttachment, attachments);
}
}
mailModel.Attachments = attachments;
return mailModel;
}
