Pinentry in emacs without X doesn't work reliably

[Tassilo Horn <tsdh@gnu.org>]

Hi all,

at work, I'm blocked from important information sources such as IRC and
the usenet.  To work around that limitation, I ssh to some server of
mine (and did I mention that I have to tunnel the ssh connection thru
HTTPS using corkscrew to access my server?!), and that server has a
current emacs master checkout which I use for Gnus and rcirc.

So far, so good.  My problem is that the server obviously has no X
server, but my connection information for gnus/rcirc are in files
encrypted using GnuPG (I use the same config files on all my machines).
When I fire up Gnus or rcirc, emacs will try to decrypt those files
transparently using EasyPG.

With my laptop, some X11/GTK/GNOME pinentry dialog pops up where I can
type in my password.  On the server, I get this (curses?) dialog:

       ┌────────────────────────────────────────────────────────────────┐
       │ Please enter the passphrase to unlock the OpenPGP secret key:  │
       │ "Tassilo Horn <my@mail.invalid>"                               │
       │ XXXX-bit ELG key, ID XXXXXXXXXXXXXXXX,                         │
       │ created 20XX-XX-XX (main key ID XXXXXXXXXXXXXXXX).             │
       │                                                                │
       │                                                                │
       │ Passphrase: __________________________________________________ │
       │                                                                │
       │         <OK>                                    <Cancel>       │
       └────────────────────────────────────────────────────────────────┘

Now the problem is, that my keyboard input doesn't seem to get thru to
that pinentry dialog reliably.  For examply, I type "geheimnis" and what
the dialog shows is, e.g., "**" as if it had only received two
characters.

So basically what I do is I type

  gggggggg
  ee
  hhhhhhhhhhhhhhhh
  eeeeee
  i
  mmmmmmm
  nnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnnn
  iiiiiiiiiiiiiiiiiii
  ssss

that is, I repeat every password char as long as no additional * shows
up at the password prompt.

Sometimes, that quirky workaround doesn't even help.  I can type "g" as
often as I want and nothing appears at the dialog.

I think I encountered that problem for quite some time now but it hasn't
been important enough to complain.  Well, now it is.

The server is running gnupg-2.1.13 and pinentry-0.9.7 where the latter
has the following pinentry programs (not sure which is used):

  /usr/bin/pinentry-curses
  /usr/bin/pinentry-emacs
  /usr/bin/pinentry-gnome3
  /usr/bin/pinentry-gtk-2
  /usr/bin/pinentry-qt
  /usr/bin/pinentry-tty

Any idea how to fix or debug that issue?

Thanks,
Tassilo