Tested with:

• Tails versions 4, 5 and 6
• Signal version 7.4.0

See howto: Tails.

Start Tails. Before logging in, make sure to enable the following option:

1. ☑️ Set an Administration Password.
2. ☑️ Enable the persistent storage

After the first start, you will be asked to create and configure the Persistent Storage. Make sure to check check the following boxes:

• ☑️ Enable persisting additionaly installed software
• ☑️ Enable Dotfiles feature

The approach used to run Signal on Tails is using Flatpak. Flatpak is a utility for software deployment and package management for Linux (Tails is a Linux).

Open Terminal and run the following command:

sudo apt update && sudo apt install flatpak --yes

Tails then asks if you want to add flatpak to your additional software. Choose: “Install every Time”.

In order to persist the configuration for Flatpak, some additional steps are required. Because they will be required after each boot, you will create a script to automate this.

The following terminal command will open a text editor to create a script in the directory /home/amnesia/Persistent/:

gnome-text-editor /home/amnesia/Persistent/flatpak-setup.sh

Content of the file:

#!/bin/sh

mkdir -p /home/amnesia/Persistent/flatpak
mkdir -p /home/amnesia/.local/share

if ! file /home/amnesia/.local/share/flatpak | grep -q 'symbolic link'; then
        rm -rf --one-file-system /home/amnesia/.local/share/flatpak
        ln -s /home/amnesia/Persistent/flatpak /home/amnesia/.local/share/flatpak
fi

mkdir -p /home/amnesia/Persistent/app
mkdir -p /home/amnesia/.var
ln -s /home/amnesia/Persistent/app /home/amnesia/.var/app

This is required so that the text file can be executed as a program:

chmod +x /home/amnesia/Persistent/flatpak-setup.sh

Run the set up script:

bash /home/amnesia/Persistent/flatpak-setup.sh

Now you create an entry in the autostart folder at /live/persistence/TailsData_unlocked/dotfiles/.config/autostart

Create the directory if it doesn't already exists:

mkdir -p /live/persistence/TailsData_unlocked/dotfiles/.config/autostart/

Open the file with the text editor:

gnome-text-editor /live/persistence/TailsData_unlocked/dotfiles/.config/autostart/FlatpakSetup.desktop

Content of the file:

[Desktop Entry]
Name=FlatpakSetup
GenericName=Setup Flatpak on Tails
Comment=This script runs the flatpak-setup.sh script on start of the user session
Exec=/live/persistence/TailsData_unlocked/Persistent/flatpak-setup.sh
Terminal=false
Type=Application

You will need to tell Flatpak from which URL to fetch the software packages:

torsocks flatpak remote-add --user --if-not-exists flathub https://flathub.org/repo/flathub.flatpakrepo

Install Signal. This command will take quite a couple of minutes:

torsocks flatpak --user install flathub org.signal.Signal

Configure Signal to use Tor for connecting to the internet:

flatpak override --user --env=HTTP_PROXY=socks://127.0.0.1:9050 org.signal.Signal
flatpak override --user --env=HTTPS_PROXY=socks://127.0.0.1:9050 org.signal.Signal

Create the directory for menu custom menu entries:

mkdir -p /live/persistence/TailsData_unlocked/dotfiles/.local/share/applications

Create the menu entry:

gnome-text-editor /live/persistence/TailsData_unlocked/dotfiles/.local/share/applications/update-flatpak.desktop

Content of the file:

[Desktop Entry]
Name=Update Flatpak apps
GenericName=Update Flatpak apps
Exec=/usr/bin/torsocks /usr/bin/flatpak update --user -y
Terminal=true
Type=Application

This file will now show up in your menu (when you hit the windows button) as “Update Flatpak apps”

You're all set. On subsequent reboots will only need to unlock the persistent volume.

Setting an administrator password will not be necessary, except you wish to do any changes to the setup.