How to force GPG to use console-mode pinentry to prompt for passwords?

Question

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?

grawity · Answer 1 · 2017-05-22T13:56:36.987

150

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

edited May 22 '17 at 13:56

answered Dec 18 '12 at 13:58

grawity

501,077

score 37 · Answer 2 · answered Dec 05 '18 at 21:34

37

On a debian box:

sudo apt install pinentry-tty
sudo update-alternatives --config pinentry

(and set it to pinentry-tty)

answered Dec 05 '18 at 21:34

John Lawrence Aspden

1,064

score 19 · Accepted Answer · answered Feb 20 '19 at 03:41

On Ubuntu 18.04, with the default installation of gpg 2.2.4, I have

/usr/bin/pinentry
/usr/bin/pinentry-gnome3
/usr/bin/pinentry-gtk-2
/usr/bin/pinentry-x11

I was able to do the following to have a text-based PIN entry:

export GPG_TTY=$(tty)
gpg-connect-agent updatestartuptty /bye >/dev/null

score 17 · Answer 4 · answered May 31 '18 at 05:58

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.

score 11 · Answer 5 · answered Oct 16 '17 at 15:49

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

score 7 · Answer 6 · answered Aug 11 '18 at 19:07

7

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.

answered Aug 11 '18 at 19:07

Aiden Woodruff

171

Victor Yarema · Answer 7 · 2022-03-22T16:56:40.330

6

Not sure which version of GPG this question was originally about. I am using GPG v2.2.19 in (K)ubuntu 20.04 LTS Focal. All I had to add was just --pinentry-mode loopback and it started to ask for a password in TTY. I didn't have to install anything. For example:

gpg --pinentry-mode loopback --export-secret-keys -a | less

edited Mar 22 '22 at 16:56

answered Mar 22 '22 at 16:51

Victor Yarema

428

PvdL · Answer 8 · 2015-11-18T09:54:05.860

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:

score 2 · Answer 9 · edited May 30 '19 at 20:53

If you do export GPG_TTY=$(tty) and unset DISPLAY it will give a TLI dialog box asking for the passphrase. Typing in the correct passphrase makes it decrypt.

If you do NOT do the above export of GPG_TTY and unset of DISPLAY it expects to use X Windows. If you launched your session (such as PuTTY) from an MS-Windows system with X11 forwarding turned on it wants to send the X-Window dialog to your MS Windows system. You can use an X emulator such as Exceed or Cygwin/X on Windows to allow the X-Window prompt for passphrase to appear on your MS-Windows box.

However, you can eliminate the need to set GPG_TTY and unset DISPLAY and getting either the TLI or GUI by running the command line with --batch option and putting the passphrase in with the --passphrase option:

gpg --batch --passphrase "<passphrase>" -o "<decrypted output file name>" --decrypt "<encrypted input file name>"

All 3 methods worked for me today on RHEL6 running gnupg2.

score 1 · Answer 10 · answered Jan 04 '17 at 11:03

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

score 0 · Answer 11 · answered Nov 06 '20 at 11:57

0

in CentOS 8 you can try :

yum -y install pinentry

answered Nov 06 '20 at 11:57

Think Big

101

score 0 · Answer 12 · answered Oct 20 '22 at 14:50

0

Simply uninstall pinentry, it has many issues on cli programs. GPG will ask for password on terminal if pinentry is not installed.

answered Oct 20 '22 at 14:50

Renato Araújo

1

score 0 · Answer 13 · answered Nov 13 '23 at 02:37

0

For me, export GPG_TTY=$(tty) did nothing - I had to install pinentry-tty and uninstall pinentry-curses. This fixed it using GPG in mutt, in screen, using SSH on a remote VPS.

answered Nov 13 '23 at 02:37

Nathan Paul Simons

101

Samveen · Answer 14 · 2024-03-13T04:36:24.520

I use GPG on a remote machine via ssh as follows:

When logging into the remote host from my laptop, I used ssh -Y to log in, which forwards all graphical program screens to be displayed on the server onto my laptop instead (Secure X Forwarding).

On the ssh server:

For pinentry, I usually install the pinentry-fltk variant, which is the most lightweight in terms of dependencies among the graphical pinentry clients (apt search pinentry)
pinentry-curses is the usual default on debian derivatives, which I update to use pinentry-fltk by updating alternatives configuration using sudo update-alternatives --config pinentry
pinentry-tty and pinentry-curses are the terminal based prompt programs, both of which have given me issues with terminal multiplexing, for example with screen, byobu or remote terminals.

Note: This is specific to Debian 11 (Bullseye) and upwards, as of Nov, 2022 till March, 2024. The exact package names will vary across other distribution families.

score 0 · Answer 15 · answered Apr 18 '24 at 14:12

I am a tmux user and usually GPG asks for the password in a different pane (I think the first one that interacted with GPG) when using pinentry-*. Whatever pinentry I set, the result was the same, and since I use WSL and also SSH, graphical options were out of the question. What I ended up doing was to set

pinentry-mode loopback'

to my $GNUPGHOME/gpg.conf and the password is always asked in the pane that was invoked. I post this as answer since the accepted answer did not work for me

How to force GPG to use console-mode pinentry to prompt for passwords?

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