protected override DecryptResult Decrypt(IContentEncryptionUi ui, string sourceFile)
{
object doc = null;
string tempfile = Path.GetTempFileName();
var decryptWrapper = new WordApplicationDecryptWrapper();
try
{
decryptWrapper.CreateHostApplication();
DecryptResult result = OpenDocument(ui, sourceFile, out doc, decryptWrapper);
if (result != DecryptResult.Ok)
{
return result;
}
// Modify document passwords, save to -another- temporary file (decryptedPath)
// Need to save twice, or for some reason the read/modify passwords get kept
Logger.LogDebug(string.Format("WordEncryption.Decrypt: Saving attachment to \"{0}\"", sourceFile));
decryptWrapper.SetOpenPassword(doc, string.Empty);
decryptWrapper.SetWritePassword(doc, string.Empty);
try
{
decryptWrapper.Save(doc);
}
catch (InvalidOperationException ex)
{
// if the document is readonly, Save() throws up UI, so instead it throws an InvalidOperationException, which we ignore...
Logger.LogInfo(ex);
}
// If you have Office 2003 & a .docx file the SaveDocumentAs cannot write over the original
// source file as it is currently locked. As a workaround we save to a temporary file
// then move the tempfile over the sourceFile
decryptWrapper.SaveDocumentAs(doc, tempfile, false, string.Empty, string.Empty);
}
finally
{
if (doc != null)
{
decryptWrapper.CloseDocument(doc, false);
}
decryptWrapper.Dispose();
}
if (File.Exists(sourceFile))
{
File.Delete(sourceFile);
}
File.Move(tempfile, sourceFile); // creates an empty file where sourceFile was -> only do if no error!!
return DecryptResult.Ok;
}
private DecryptResult OpenDocument(IContentEncryptionUi ui, string sourceFile, out object doc, WordApplicationDecryptWrapper decryptWrapper)
{
bool bUseDummyModifyPassword = false;
doc = null;
DecryptResult result = DecryptResult.Skip;
// TODO - Fix the handling of Modify passwords to correctly validate them.
// Currently any Modify password is stripped from the document when it is saved.
// This is due to the fact that we don't correctly verify the Modify password when opening
// the document and as a result it might be possible for the user to enter an incorrect password.
// When saving, the incorrect password would still be applied causing problems for the receiver.
string extension = System.IO.Path.GetExtension(sourceFile);
switch (extension.ToLower())
{
case ".doc":
case ".docx":
case ".docm":
case ".dotx":
case ".dotm":
result = this.GetAndCheckPasswords(ui);
break;
case ".rtf":
result = this.GetAndCheckModifyPassword(ui);
break;
default:
result = this.GetAndCheckOpenPassword(ui);
break;
}
if (result == DecryptResult.Ok)
{
// Don't use the cache to decrypt because password errors leave word in a state where
// subsequent calls return RPC_UNAVAIABLE.
try
{
doc = decryptWrapper.Decrypt(sourceFile, false, string.IsNullOrEmpty(OpenPassword) ? DUMMY_PASSWORD : OpenPassword, string.IsNullOrEmpty(ModifyPassword) ? DUMMY_PASSWORD : ModifyPassword, AttachmentFileType);
// If the user typed a Modify or Open password for a document that didn't need one
// remove it here, otherwise it will be added to the saved document.
if (!decryptWrapper.ShouldHandleOpenPassword(doc))
{
OpenPassword = "";
}
if (!decryptWrapper.ShouldHandleWritePassword(doc))
{
ModifyPassword = "";
}
// Bug fix for VE: 97
// In OfficeXP, casting Microsoft.Office.Interop.Word.DocumentClass to Microsoft.Office.Interop.Word.Document fails at
// runtime. Use _Document instead.
Word12Interop._Document wordDoc = doc as Word12Interop._Document;
DisableReadingLayout(wordDoc);
Logger.LogDebug("Document Protection Type: " + wordDoc.ProtectionType);
if( wordDoc.ProtectionType != Microsoft.Office.Interop.Word.WdProtectionType.wdNoProtection )
{
m_typeProtect = wordDoc.ProtectionType;
if (!CanUnprotectDocument(wordDoc))
{
result = this.GetDocumentProtectionPassword(ui);
if (result == DecryptResult.Ok)
{
if (string.IsNullOrEmpty(DocumentProtectionPassword))
{
m_typeProtect = Microsoft.Office.Interop.Word.WdProtectionType.wdNoProtection;
}
else if (m_typeProtect != Microsoft.Office.Interop.Word.WdProtectionType.wdNoProtection)
{
object password = DocumentProtectionPassword;
wordDoc.Unprotect(ref password);
Logger.LogDebug(string.Format("WordEncryption.OpenDocument: Successfully unprotected document \"{0}\"", sourceFile));
}
}
}
}
}
catch(UnauthorizedAccessException)
{
Logger.LogInfo("Incorrect password. Exit word, and retry");
DocumentProtectionPassword = string.Empty;
decryptWrapper.ForceQuit();
throw;
}
catch (COMException ex)
{
Logger.LogError("Office Open Exception");
Logger.LogError(ex);
// handle exceptions for incorrect encryption passwords and the document preotection password
if( ex.ErrorCode == unchecked((int)0x800A03EC) || ex.ErrorCode == unchecked((int)0x800A156D) )
{
Logger.LogInfo("Incorrect password. Exit word, and retry");
DocumentProtectionPassword = string.Empty;
decryptWrapper.ForceQuit();
throw new UnauthorizedAccessException("Failed to open encrypted file - incorrect password");
}
throw;
}
finally
{
// Reset any dummy password which may have been used so that the
// document doesn't incorrectly get saved with it.
if (bUseDummyModifyPassword)
{
ModifyPassword = "";
}
}
}
return result;
}
