There are several places where someone finds information about how to trouble shoot a crypto application problem.

TODO: link to relevant sections in other documentation.

For problems with adele see EmailExercisesRobot.

Contents

  1. General
  2. Decryption Failure with Gpg4win-3.1.2 or later
    1. Update key to ensure MDC is used even by older versions
  3. Can't sign files anymore
    1. Possible Reason: Activated VS-NfD mode
  4. Windows > 8 and Server 2012 Task Scheduler Problems
  5. GpgOL won't load in Outlook
  6. GpgOL does not work
  7. GpgOL: Not all attachments can be shown
    1. Possible reason: Attachment too big
  8. Hints / Tips
    1. Command line operations
      1. Passphrase on the command line
    2. Enable GpgOL debugging
    3. Manually update GpgOL to a beta
    4. Antivirus reports on Gpg4win
    5. Disable Gpg4win update check and notification
    6. Restoring corrupted Archives created by Kleopatra

General

  1. If the problem is with GpgOL, try the operation with GpgEX or Kleopatra, to exclude Outlook's influence. Note that if GpgEX/Kleopatra works, you have a fallback solution to just work via files and send them by attachment, so can can still use crypto, but with less comfort.
  2. If GUI frontend applications fail, try to do the operations on the command line. This way you can often exclude that the problem is within the frontend. And you sometimes get additional helpful messages.
  3. Look at or activate and look at additional diagnostic output (see links at the top). There are many places where additional output can be found or enabled.
  4. When you face problems while trying to get a public key it can be helpful to use the dirmngr.
  5. Try to reproduce, sometimes a different installation or a different computer gives you an idea about the difference between a running and a problem case.
  6. Precisely check the version numbers of components.
  7. Check general operating or usage issues. Things like a full harddrive or wrong filesystem permissions.
  8. Run Gpg4win as user, not as administrator.

Decryption Failure with Gpg4win-3.1.2 or later

Starting with Gpg4win-3.1.2 the MDC message integrity mechanism, which has been well established for over 15 years, is now enforced by GnuPG. The reason for this was the public attention to attacks possible against messages without MDC with the publication of "EFail".

Since Gpg4win-3.1.3 Kleopatra offers to decrypt such messages anyway if they were done using an old encryption algorithm. In that case you only need to click on the decrypt anyway button. For messages that were encrypted using modern algorithms but still don't use MDC there is a hard failure that will be shown in diagnostics. Such new algo, no MDC, messages are supposed to be rare and might be an indication of broken / insecure software or configuration.

You can fix the error by re-encrypting it. Afterwards it can be used as usual in Kleopatra and will be integrity protected.

To decrypt it, even without an MDC, open the command line (see below for additional hints) and decrypt your file like:

    gpg --ignore-mdc-error --decrypt "path_to_your_file"

Additionally to decrypting this will list the keyids of the recipients of that message, which you can then use in the command to re-encrypt the message.

    gpg -r "recipient_keyid_1" -r "recipient_keyid_2" --encrypt "path_to_your_file"

Alternatively only using Kleopatra you can also decrypt it with Gpg4win-3.1.1 and then encrypt it again after your key has been updated to ensure MDC is used (see below)

Update key to ensure MDC is used even by older versions

Can't sign files anymore

Possible Reason: Activated VS-NfD mode

kleopatra_vs_nfd_compliant_communication_not_possible.png

This error is shown when you use a version of Gpg4win which is not compliant to VS-NfD while the VS-NfD mode is activated. There are two options to solve this issue:

Windows > 8 and Server 2012 Task Scheduler Problems

GnuPG uses (as suggested by Microsoft and usual) %APPDATA%\gnupg to store data on Windows. When launched from the Task Scheduler %APPDATA% is not always set to the correct users directory. (If you launch it with system privileges it is another place altogether). GnuPG as a result is unable to find the Keys or configuration in the directory Windows provides.

This is a known Windows bug. See the Knowledge Base article Or This technet discussion

Instead of the Workaround mentioned in the knowledge base article GnuPG provides you with the option to set the Home directory as part of the command. (--homedir) Which makes it easy to workaround that bug.

For example:

  gpg --homedir c:\Users\aheinecke\AppData\Roaming\gnupg --encrypt -r <recipient> <file>

Would ignore the broken value of %APPDATA% and use the keys stored in c:\Users\aheinecke\AppData\Roaming\gnupg instead. Make sure access rights are set accordingly of course so that this works with the user the Scheduled task runs under.

GpgOL won't load in Outlook

If it is correctly installed and enabled:

Check in the Windows Registry that

HKEY_CURRENT_USER\Software\Microsoft\Office\Outlook\Addins\GNU.GpgOL LoadBehavior

is set to 3.

In the following Registry Keys replace <VERSION> with your Outlook Version. The <VERSION> values are:

Additionally, if they exist, delete all REG_BINARY Entries under:

HKEY_CURRENT_USER\Software\Microsoft\Office\<VERSION>\Outlook\Resiliency\DisabledItems

and

HKEY_CURRENT_USER\Software\Microsoft\Office\<VERSION>\Outlook\Resiliency\CrashingAddinList

Finally create the Registry Key:

HKEY_CURRENT_USER\Software\Microsoft\Office\<VERSION>\Outlook\Resiliency\DoNotDisableAddinList

And add a REG_DWORD entry with name GNU.GpgOL and value 1.

You can also enable logging even if Outlook does not start by launching c:\Program Files\Gpg4win\bin\gpgolconfig.exe directly. This gives you the config dialog of Gpg4win with the usual debugging options.

GpgOL does not work

Check if you have one of the known incompatible Addons.

GpgOL: Not all attachments can be shown

gpgol_not_all_attachments_can_be_shown.png

Possible reason: Attachment too big

Outlook has a limit for the size of files. When you are using IMAP or POP3 the limit is 20 MB. When you use an Exchange Server the limit depends on the settings of the server (default: 10 MB).

If you try to read an encrypted email which contains a bigger file the message shown above appears. Microsoft published an instruction to increase the limit in the registry editor.

Hints / Tips

Command line operations

The manual of the GnuPG (crypto engine) will describe the command line usage in detail, but for testing we give some simple commands here.

First you need to open the "cmd.exe" command line application in windows. Then you can type commands at the prompt. For good results, create a new directory and change into it with cd and create or copy a testfile you can operate on for, example hello.txt.

An example to use your own key to sign something with CMS with double verbose output:

gpgsm.exe -vv --sign hello.txt >hello.p7s

An example to decrypt something with OpenPGP, no extra output

gpg --decrypt hello.gpg

and now with full diagnostic output (be careful when sharing with others, this may contain sensitive information), usually you start with no diagnostic output, then add "-v"s and additional "--debug" options. (With gpg --debug help showing available choices to give after --debug.)

gpg --debug-all -vvv hello.gpg

Passphrase on the command line

The private key, which is protected by a passphrase, is handled by gpg-agent. This means that with GnuPG 2.1 adding --passphrase on the command line will no longer work out of the box. If you really don't want a passphrase (you have it in a script or the command line history anyway) It is suggested to remove the passphrase from that key. Other options are:

e.g.:

  gpg --pinentry-mode loopback --passphrase <yourpassphrase> -d <somefile>

Enable GpgOL debugging

GpgOL can log what it does internally. You might be asked for such a debug log to analyze a problem.

To enable it:

The value of enableDebug -> If set to 1 it logs less and should not leak any private data except Mail Addresses. If set to 1922 the log will contain the plaintext of decrypted messages, so only use that if you have a test mail or some unconfidential mail.

Manually update GpgOL to a beta

Sometimes after reporting an issue on https://dev.gnupg.org you might be asked to install an updated GpgOL binary which contains a fix that should be tested, as it is sometimes impossible for the developers to reproduce the exact conditions for a problem.

The binaries can be found as HTTPS secured download under: https://files.gpg4win.org/Beta/gpgol/

Look for the directory of the version you want to use and open it. In there you find the corresponding source code and two binaries.
The gpgol.dll in the top level binary is the 32 Bit version of GpgOL.
The gpgol.dll in the x64 sub directory is the 64 Bit version of GpgOL.

Which version you need depends on your Outlook Version. You can find out if you have a 32bit or 64bit outlook by looking at
File -> Office Account -> Info about Microsoft Outlook.
64 Bit versions have it noted at the top of the info window.

outlook-info.png

Once you have downloaded the correct version you need to *shutdown Outlook* and replace the gpgol.dll in the installation directory of Gpg4win. For the 64 bit version the gpgol.dll must be placed in the bin_64 subfolder.

The default paths are:
c:\Program Files (x86)\Gpg4win\bin\gpgol.dll for 32 bit.
c:\Program Files (x86)\Gpg4win\bin_64\gpgol.dll for 64 bit.

General warning: Beta versions are naturally less tested, than stable released versions. They still may have critical defects. On the other hand, they may also have important defects fixed. Depending on the need of your security level, you should estimate if it is okay to use a beta version for your production environment with real keys. Rule of thumb, unless noted otherwise, we believe that it is okay to use a beta version in production settings for normal security requirements and as a precaution do should use it in high security environments or with highly sensitive key-material.

Antivirus reports on Gpg4win

See Gpg4win/AntiVirusSoftware

Disable Gpg4win update check and notification

To disable and hide the update check and notification of Gpg4win create a new file in the Gpg4win Installation directory in the subfolder "share". The file needs to have the name "kleopatrarc" and no file extension.

e.g.: c:\program files\gpg4win\share\kleopatrarc

The contents of the file should be:

[KDE Action Restrictions][$i]
action/help_check_updates=false

[UpdateNotification][$i]
NeverShow=true

Restoring corrupted Archives created by Kleopatra

Kleopatra before Version 3.1.6 had an issue that might have caused the creation of corrupted archives. T4332 If you are affected get errors when extracting such an archive the good news are: The data can be restored with some effort because there were only "bad blocks" added and no data removed.

To repair such an Archive:

If you are in luck and your data does not naturally contain blocks of 512 zeros this should do the trick. If your data can contain blocks of 512 zeros naturally, e.g. pdfs. It gets more complicated. In that case your best bet is to look for "candidate blocks" remove them. Run gpgtar and check if the errors changed.

If you need assistance with that you can ask on one of the channels under: https://www.gpg4win.org/community.html

TroubleShooting (last edited 2022-11-01 15:16:09 by Christoph Klassen)