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.

Tails configuration

• Create a Persistent Storage: https://tails.net/doc/persistent_storage/
• Enable the Additional Software feature of Tails persistence: https://tails.net/doc/persistent_storage/additional_software/
• Enable Dotfiles feature: https://tails.net/doc/persistent_storage/configure/

Reboot

When logging in after the reboot, unlock persistence volume and set an Administration Password.

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). WARNING: since you download (and update) Signal from flatpak source you now depend on Flatpaks integrity!!!

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”.

Put these commands into a script (a simple text file) in persistent folder i.e. /home/amnesia/Persistent/flatpak-setup.sh. You can do so by opening it from the Terminal with a text editor:

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

• Make script executable

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

• Add script to autostart

Create a file: /live/persistence/TailsData_unlocked/dotfiles/.config/autostart/FlatpakSetup.desktop. To do so, first create the directory, then open the file with a text editor:

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

Reboot

When logging in after the reboot, unlock persistence volume and set an Administration Password.

Open Terminal:

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

torify flatpak install flathub org.signal.Signal

(This will take quite a couple of minutes.)

Put these commands into a script (a simple text file) in /home/amnesia/Persistent/signal.sh. To do so, open the file in a text editor:

gnome-text-editor /home/amnesia/Persistent/signal.sh

Content of the file:

#!/bin/sh

export HTTP_PROXY=socks://127.0.0.1:9050
export HTTPS_PROXY=socks://127.0.0.1:9050
flatpak run org.signal.Signal

• Make script executable

chmod +x /home/amnesia/Persistent/signal.sh

• Add script to applications

Create a file: /live/persistence/TailsData_unlocked/dotfiles/.local/share/applications/Signal.desktop. To do so, first create the directory, then open the file with a text editor:

mkdir -p /live/persistence/TailsData_unlocked/dotfiles/.local/share/applications
gnome-text-editor /live/persistence/TailsData_unlocked/dotfiles/.local/share/applications/Signal.desktop

Content of the file:

[Desktop Entry]
Name=Signal
GenericName=Signal Desktop Messenger
Exec=/home/amnesia/Persistent/signal.sh
Terminal=false
Type=Application
Icon=/home/amnesia/.local/share/flatpak/app/org.signal.Signal/current/active/files/share/icons/hicolor/128x128/apps/org.signal.Signal.png

Reboot and unlock persistence volume. (You need to unlock persistence volume every time you want to use Signal)

Signal now shows as part of the Gnome applications with a nice Signal icon (hit “windows” button and search for “Signal”).

It's possible to start Signal like this as well:

cd /home/amnesia/Persistent && ./signal.sh

IMPORTANT: to check for updates and update Signal you have to manually run:

torify flatpak update