Using gpg from a console-based environment such as ssh sessions fails because the GTK pinentry dialog cannot be shown in a SSH session.

I tried unset DISPLAY but it did not help. The GPG command line options do not include a switch for forcing the pinentry to console-mode.

Older GPG versions offered a text-based prompt that worked fine in SSH sessions but after the upgrade it just fails.

There is the --textmode command line switch but apparently, it does something else.

What would be the proper and clean way of getting plain-text pin entry for remote sessions?

  • DISPLAY="" gpg2 ... helped me, I also installed pinentry-curses + pinentry-tty beforehand, not sure if they are strictly necessary – ThorSummoner May 10 at 21:45
up vote 74 down vote accepted

To change the pinentry permanently, append the following to your ~/.gnupg/gpg-agent.conf:

pinentry-program /usr/bin/pinentry-tty

(In older versions which lack pinentry-tty, use pinentry-curses for a 'full-terminal' dialog window.)

Tell the GPG agent to reload configuration:

gpg-connect-agent reloadagent /bye
  • 7
    It's not completely "sane". Normally, gpg-agent should itself detect the presence or lack of $DISPLAY and choose the apropriate pinentry... – grawity Dec 19 '12 at 15:00
  • 3
    The agent is most likely capable of detecting the presence of a running xorg. But having a DISPLAY defined does not necessarily mean I can or want to use it, for example, when connected over SSH. – ccpizza Dec 19 '12 at 17:34
  • 2
    @lfxgroove: the problem is that su does not change the ownership of your TTY, so you need to manually chown it. See this article. – Rufflewind Oct 9 '15 at 16:22
  • 2
    @Starx: You create one. – grawity Dec 8 '16 at 10:39
  • 3
    Another tip: to view all the available options, type ls /usr/bin | grep pinentry. I see pinentry, pinentry-curses, pinentry-emacs, pinentry-gnome3, pinentry-gtk2, pinentry-qt and pinentry-tty. This way you can choose the one that suits you better, if you don't have the lack of $DISPLAY issue. – Jeffrey Lebowski Jan 10 '17 at 12:56

I just had this problem on Ubuntu 16.04.3 when trying to generate/install a private key using gpg2 (2.1.11) on a system account without a password, and on a user account over ssh. Nothing worked giving:

gpg: key FE17AE6D/FE17AE6D: error sending to agent: Permission denied
gpg: error building skey array: Permission denied

I then found this which worked for me, so in brief:

pico ~/.gnupg/gpg-agent.conf
# add: allow-loopback-pinentry
gpg-connect-agent reloadagent /bye
gpg2 --pinentry-mode loopback --import private.key

To prevent the pinentry popup you could ssh localhost. Optionally forcing X11 disabled, -x Disables X11 forwarding. See the full example below.

patrick@patrick-C504:~$ ssh localhost
patrick@localhost's password: 
Welcome to Ubuntu 14.04.3 LTS (GNU/Linux 3.13.0-68-generic x86_64)

 * Documentation:  https://help.ubuntu.com/

Last login: Mon Nov 16 22:48:53 2015 from localhost
patrick@patrick-C504:~$ gpg --gen-key
gpg (GnuPG) 1.4.16; Copyright (C) 2013 Free Software Foundation, Inc.
This is free software: you are free to change and redistribute it.
There is NO WARRANTY, to the extent permitted by law.

Please select what kind of key you want:
   (1) RSA and RSA (default)
   (2) DSA and Elgamal
   (3) DSA (sign only)
   (4) RSA (sign only)
Your selection? 4
RSA keys may be between 1024 and 4096 bits long.
What keysize do you want? (2048) 
Requested keysize is 2048 bits
Please specify how long the key should be valid.
         0 = key does not expire
      <n>  = key expires in n days
      <n>w = key expires in n weeks
      <n>m = key expires in n months
      <n>y = key expires in n years
Key is valid for? (0) 
Key does not expire at all
Is this correct? (y/N) y

You need a user ID to identify your key; the software constructs the user ID
from the Real Name, Comment and Email Address in this form:
    "Heinrich Heine (Der Dichter) <heinrichh@duesseldorf.de>"

Real name: Foo
Name must be at least 5 characters long
Real name: FooBar
Email address: foorbar@foo.bar
Comment: 
You selected this USER-ID:
    "FooBar <foorbar@foo.bar>"

Change (N)ame, (C)omment, (E)mail or (O)kay/(Q)uit? o
You need a Passphrase to protect your secret key.

gpg: gpg-agent is not available in this session
Enter passphrase:
  • 3
    Which X11 features specifically should be disabled? I personally know the answer to my question, the author does not, so the answer seems incomplete without this information. – Ramhound Nov 17 '15 at 12:26
  • ssh'ing to local host was enough for me, but optionally -x Disables X11 forwarding. should prevent any X11 forwarding. Answer is updated. – PvdL Nov 18 '15 at 9:45
  • I prefer this solution, given that pinentry over -X doesn't show up – I'm normally physically at my laptop, where I want X pinentry (so I don't want to edit a conf file all the time), but if I happen to ssh -X into it I might still want a curses pinentry. Of course, ideally, the gtk pinentry would actually work over ssh -X :-/ – unhammer Jun 5 '16 at 13:29

I'll copy my answer from over here...

Looking at man pinentry-gnome3, I see this:

   pinentry-gnome3  implements  a PIN entry dialog based on GNOME 3, which
   aims to follow the GNOME Human Interface Guidelines as closely as  pos‐
   sible.   If the X Window System is not active then an alternative text-
   mode dialog will be used.  There are other flavors that  implement  PIN
   entry dialogs using other tool kits.

Unfortunately, this text-mode fallback doesn't work for me. It seems others have the same issue. However, this comment spurred my to try a different GUI pin-entry program: pinentry-gtk2. You can switch like this:

> sudo update-alternatives --config pinentry
There are 3 choices for the alternative pinentry (providing /usr/bin/pinentry).

  Selection    Path                      Priority   Status
------------------------------------------------------------
* 0            /usr/bin/pinentry-gnome3   90        auto mode
  1            /usr/bin/pinentry-curses   50        manual mode
  2            /usr/bin/pinentry-gnome3   90        manual mode
  3            /usr/bin/pinentry-gtk-2    85        manual mode

Press <enter> to keep the current choice[*], or type selection number: 3
update-alternatives: using /usr/bin/pinentry-gtk-2 to provide /usr/bin/pinentry (pinentry) in manual mode

Once I switched, it worked perfectly for me! In a terminal on the desktop, it will use the GUI password entry, but when I ssh into my machine, it will use a text-mode password entry.

If you don't have it, install pinentry-curses with yum or apt-get.

Then, run:

sudo update-alternatives --config pinentry

And select pinentry-curses from the list.

I found the "full example" in PvdL's answer a bit confusing, here's what I do:

ssh -X machine
# work hack hack work until I need something from gpg
ssh -x localhost -p$port
gpg2 --decrypt file.gpg
# enter password to pinentry
exit
# now the key is unlocked in gpg-agent, and I can keep decrypting files
# from my X ssh session without being asked for the password

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