#206 Enigmail shows OpenPGP/MIME signatures as attachment

wont-fix
nobody
None
1.5.2
Minor
17.0.9
2.0.22
Linux
---
2014-05-04
2013-10-28
Till Schäfer
No

Enigmail shows signatures from OpenPGP/MIME as normal attachments. While this is technically correct, it does not reflect the normal use case. This makes it impossible to quickly find mails with "real" attachments. You have to open each mail and see if there is another attachment beside signature.asc.

Therefore, Enigmail should not show the signature as normal attachment. Alternatively it should provide a possibility to access the raw signature over the details drop down menu from the info line above a mail.

Discussion

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  • For me, Thunderbird with Enigmail installed shows no attachment for a PGP/MIME signed mail whether or not it is encrypted. In fact, Enigmail is hiding the MIME attachment which is necessary to technically transport the signature. It is not possible to hide this attachment for someone with a not OpenPGP aware mail program.

     
  • Till Schäfer
    Till Schäfer
    2013-11-13

    For me the problem still exist when using an encrypted and signed mail. I have attached the problematic mail. However, i dont know if it helps you because the content is encrypted. If you need a decryptable Mail, i can send you a test mail (you can send me your e-mail address to till2 dot schaefer at tu minus dortmund dot de).

    • The Mail was send using KMail 4.11.3 .
    • Tested with Enigmail 1.6 and Thunderbird 17.0.9
     
    Attachments
  • Till Schäfer
    Till Schäfer
    2013-11-13

    OK, when i send a mail from thunderbird, the attachement is not shown.
    So this bug seems related to the composer KMail. I cannot judge if this is a bug in KMail or in Enigmail, but KMail has the same problem for pgp/mime mails from thunderbird.

     
  • Till Schäfer
    Till Schäfer
    2013-11-13

    thunderbird composed mail

     
    Attachments
  • Hi,

    I cannot find something wrong about the attachment "problematic_mail.txt". The only thing why something could show up as attachment is the "Content-Disposition: attachment" in the PGP/MIME version section of the mail. This is inserted by KMai. Enigmail refrains from such a MIME header. Is the attachment shown in Thunderbird after decryption showing only a single line containing "Version: 1"?

    I'll write to you, requesting an encrypted mail.

     
  • I guess the problem is that the message follows RFC 3156, section 6.1 (in other words, you create a PGP/MIME signed message and then encrypt that message, creating an outer PGP/MIME encrypted message). This will lead to a "signature.asc" file or similar. Thunderbird currently does not hide that attachment automatically, and Enigmail doesn't do anything to instruct Thunderbird to do so.

    The difference to PGP/MIME mails created by Enigmail is that Enigmail uses the "combined method" as specified in RFC 3156, section 6.2, that is the message is signed and encrypted in one step.

    I don't understand the KDE bug you opened, you seem to describe something completely different than here.

     
  • Till Schäfer
    Till Schäfer
    2013-12-23

    @Ludwig: i have send you an Email. The attachment contains the complete signature.

    @Patrick: The kde bug report describes the reverse problem: If i send an email with thunderbird and use openpgp/mime there is an attachment signature.asc shown as well in kmail. Therefore, this bug works in both directions. Only kmail-kmail and thunderbird-thunderbird work correctly, but neither kmai-thunderbird nor thunderbird-kmail work.

     
  • The testmail I received from Till shows this behaviour clearly. Patrick, your interpretation is correct, there are two gpg operations when opening this testmail. The first is for decryption, the second for verification of the then visible signature. This signature is displayed as attachment of the decrypted mail.

    It's good that Enigmail can deal with section 6.1 PGP/MIME mails and correctly verify them, but I think we should hide the attachment - like for PGP/MIME signed mails.

     
    • status: open --> wont-fix
     
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