A more modern howto is available here (via Tor Onion Service here)

(heavily based on: bisco.org )

Tested with:

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

See howto: Tails and run it.

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

1. Set an Administration Password.

After the first start, you will be asked if you want to enable and configure the Persistent Storage:

1. Enable the Persistent Storage
2. Configure the Persistent Storage:
   • Enable persisting additionaly installed software:
   • Enable Dotfiles feature: https://tails.net/doc/persistent_storage/configure/

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:

sudo apt update && sudo apt install flatpak

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

First you create a setup script. 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

chmod +x /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 reboot for the script to take effect.

When logging in after the reboot:

• Unlock persistent volume
• Set an administration password.

In the terminal, configure the Package repository for Flatpak:

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

Install the Signal app with Flatpak (This will take quite a couple of minutes):

torsocks flatpak 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.