bug#20634: 25.0.50; Conflict between Tramp and EasyPG

[Jens Lechtenboerger <jens.lechtenboerger@fsfe.org>]

Hi there,

I use EasyPG for transparent access of encrypted files with
extension .gpg.  If I copy an encrypted file, say test.gpg, via ssh
(Tramp) to a remote location, then I’m asked what public key to use
for encryption (none for symmetric encryption), and the encrypted
file is encrypted again, rendering it useless from within Emacs.
(If I open the remote file via Tramp, the outer layer of encryption
is removed, and I see the original encrypted file.)

Recipe:

0. Encrypt a file: test.gpg

1. emacs -Q

2. Open directory of test.gpg (C-x C-f).

3. Copy (C) the file to a remote location
   (e.g., /user@localhost:/tmp).

   The key chooser opens.  Copy is cancelled if I cancel the choice.
   Otherwise, a remote file is created, which is not a copy but an
   encrypted file with two layers of encryption.

4. Open the remote file (C-x C-f /user@localhost:/tmp/test.gpg).
   Observe encrypted data.

In contrast, if I copy an encrypted file to a local directory, it is
copied without extra encryption.

Note also that if I copy a plaintext file (test.txt) locally to one
with gpg extension (test.gpg), it remains a plaintext file.  If I
copy that to a remote location, it gets encrypted.  This may be a
bug or a feature, but is certainly inconsistent behavior.

Best wishes
Jens