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Merge pull request #28 from just1fi3d/master
Encrypted/Signed Email changes for Issue #15
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,172 @@ | ||
| using System; | ||
| using System.Collections.Generic; | ||
| using System.Linq; | ||
| using System.Text; | ||
| using System.Net.Mail; | ||
| using System.IO; | ||
| using System.Text.RegularExpressions; | ||
| using System.Collections; | ||
| using System.Collections.Specialized; | ||
| using System.Net.Mime; | ||
| using System.Security.Cryptography.X509Certificates; | ||
| using System.Security.Cryptography.Pkcs; | ||
|
|
||
| namespace XstReader | ||
| { | ||
| static class MailMessageMimeParser | ||
| { | ||
|
|
||
| //parse mime message into a given message object adds alll attachments and inserts inline content to message body | ||
| public static void parseMessage(Message m, String mimeText) | ||
| { | ||
| Dictionary<string, string> headers = getHeaders(new StringReader(mimeText)); | ||
| string Boundary = Regex.Match(headers["content-type"], @"boundary=""(.*?)""", RegexOptions.IgnoreCase).Groups[1].Value; | ||
| string[] messageParts = getMimeParts(Boundary, mimeText); | ||
|
|
||
| foreach(string part in messageParts) | ||
| { | ||
| Dictionary<string, string> partHeaders = getHeaders(new StringReader(part)); | ||
| //message body | ||
| if (partHeaders.Keys.Contains("content-type") && partHeaders["content-type"].Trim().Contains("text/html;")) | ||
| { | ||
| m.BodyHtml = DecodeQuotedPrintable(partHeaders["mimeBody"]); | ||
| m.NativeBody = BodyType.HTML; | ||
| } | ||
| //real attachments | ||
| else if (partHeaders.Keys.Contains("content-disposition") && partHeaders["content-disposition"].Trim().Contains("attachment;")) | ||
| { | ||
| string filename = Regex.Match(partHeaders["content-disposition"], @"filename=""(.*?)""", RegexOptions.IgnoreCase).Groups[1].Value; | ||
| //add base64 content to an attachement on the message. | ||
| Attachment a = new Attachment(); | ||
| a.LongFileName = filename; | ||
| a.AttachMethod = AttachMethods.afByValue; | ||
| a.AttachmentBytes = Convert.FromBase64String(partHeaders["mimeBody"]); | ||
| a.Size = a.AttachmentBytes.Length; | ||
| m.Attachments.Add(a); | ||
| } | ||
| //inline images | ||
| else if (partHeaders.Keys.Contains("content-id")) | ||
| { | ||
| Attachment a = new Attachment(); | ||
| string contentid = Regex.Match(partHeaders["content-id"], @"<(.*)>", RegexOptions.IgnoreCase).Groups[1].Value; | ||
| string name = Regex.Match(partHeaders["content-type"], @".*name=""(.*)""", RegexOptions.IgnoreCase).Groups[1].Value; | ||
| a.AttachMethod = AttachMethods.afByValue; | ||
| a.ContentId = contentid; | ||
| a.LongFileName = name; | ||
| a.Flags = AttachFlags.attRenderedInBody; | ||
| a.AttachmentBytes = Convert.FromBase64String(partHeaders["mimeBody"]); | ||
| a.Size = a.AttachmentBytes.Length; | ||
| m.Attachments.Add(a); | ||
| } | ||
| } | ||
| } | ||
|
|
||
| //decrpts mime message bytes with a valid cert in the user cert store | ||
| // returns the decrypted message as a string | ||
| public static string decryptMessage(byte[] encryptedMessageBytes) | ||
| { | ||
| //get cert store and collection of valid certs | ||
| X509Store store = new X509Store("MY", StoreLocation.CurrentUser); | ||
| store.Open(OpenFlags.ReadOnly | OpenFlags.OpenExistingOnly); | ||
| X509Certificate2Collection collection = (X509Certificate2Collection)store.Certificates; | ||
| X509Certificate2Collection fcollection = (X509Certificate2Collection)collection.Find(X509FindType.FindByTimeValid, DateTime.Now, false); | ||
|
|
||
| //decrypt bytes with EnvelopedCms | ||
| EnvelopedCms ec = new EnvelopedCms(); | ||
| ec.Decode(encryptedMessageBytes); | ||
| ec.Decrypt(fcollection); | ||
| byte[] decryptedData = ec.ContentInfo.Content; | ||
|
|
||
| return System.Text.Encoding.ASCII.GetString(decryptedData); | ||
| } | ||
|
|
||
| //Signed messages are base64 endcoded and broken up with \r\n | ||
| //This extracts the base64 content from signed message that has been wrapped in an encrypted message and decodes it | ||
| // returns the decoded message string | ||
| public static string DecodeSignedMessage(string s) | ||
| { | ||
| //parse out base64 encoded content in "signed-data" | ||
| string base64Message = s.Split(new string[] { "filename=smime.p7m" }, StringSplitOptions.None)[1]; | ||
| string data = base64Message.Replace("\r\n", ""); | ||
|
|
||
| // parse out signing data from content | ||
| SignedCms sc = new SignedCms(); | ||
| sc.Decode(Convert.FromBase64String(data)); | ||
|
|
||
| return System.Text.Encoding.ASCII.GetString(sc.ContentInfo.Content); | ||
| } | ||
|
|
||
| //parse out mime headers from a mime section | ||
| //returns a dictionary with the header type as the key and its value as the value | ||
| private static Dictionary<string, string> getHeaders(StringReader mimeText) | ||
| { | ||
| Dictionary<string, string> Headers = new Dictionary<string, string>(); | ||
|
|
||
| string line = string.Empty; | ||
| string lastHeader = string.Empty; | ||
| while ((!string.IsNullOrEmpty(line = mimeText.ReadLine()) && (line.Trim().Length != 0))) | ||
| { | ||
|
|
||
| //If the line starts with a whitespace it is a continuation of the previous line | ||
| if (Regex.IsMatch(line, @"^\s")) | ||
| { | ||
| Headers[lastHeader] = Headers[lastHeader] + " " + line.TrimStart('\t', ' '); | ||
| } | ||
| else | ||
| { | ||
| string headerkey = line.Substring(0, line.IndexOf(':')).ToLower(); | ||
| string value = line.Substring(line.IndexOf(':') + 1).TrimStart(' '); | ||
| if (value.Length > 0) | ||
| Headers[headerkey] = line.Substring(line.IndexOf(':') + 1).TrimStart(' '); | ||
| lastHeader = headerkey; | ||
| } | ||
| } | ||
|
|
||
| string mimeBody = ""; | ||
| while ((line = mimeText.ReadLine()) != null) | ||
| { | ||
| mimeBody += line +"\r\n"; | ||
| } | ||
| Headers["mimeBody"] = mimeBody; | ||
| return Headers; | ||
| } | ||
|
|
||
| // splits a mime message into its individual parts | ||
| // returns a string[] with the parts | ||
| private static string[] getMimeParts(string initialBoundary, string mimetext) | ||
| { | ||
| String partRegex = @"\r\n------=_NextPart_.*\r\n"; | ||
| string[] test = Regex.Split(mimetext, partRegex); | ||
|
|
||
| return test; | ||
| } | ||
|
|
||
| //decodes quoted printable text into UTF-8 | ||
| // returns the decoded text | ||
| private static string DecodeQuotedPrintable(string input) | ||
| { | ||
| Regex regex = new Regex(@"(\=[0-9A-F][0-9A-F])+|=\r\n", RegexOptions.IgnoreCase); | ||
| string value = regex.Replace(input, new MatchEvaluator(HexDecoderEvaluator)); | ||
| return value; | ||
| } | ||
|
|
||
| //converts hex endcoded values to UTF-8 | ||
| //returns the UTF-8 representation of the hex encoded value | ||
| private static string HexDecoderEvaluator(Match m) | ||
| { | ||
| if (m.Groups[1].Success) | ||
| { | ||
| byte[] bytes = new byte[m.Value.Length / 3]; | ||
|
|
||
| for (int i = 0; i < bytes.Length; i++) | ||
| { | ||
| string hex = m.Value.Substring(i * 3 + 1, 2); | ||
| int iHex = Convert.ToInt32(hex, 16); | ||
| bytes[i] = Convert.ToByte(iHex); | ||
| } | ||
| return System.Text.Encoding.UTF8.GetString(bytes); | ||
| } | ||
| return ""; | ||
| } | ||
| } | ||
| } |
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