How to install Signal dekstop to archlinux

Download Signal Desktop

eg. latest version v1.0.41

$ curl -s https://updates.signal.org/desktop/apt/pool/main/s/signal-desktop/signal-desktop_1.0.41_amd64.deb \
    -o /tmp/signal-desktop_1.0.41_amd64.deb

Verify Package

There is a way to manually verify the integrity of the package, by checking the hash value of the file against a gpg signed file. To do that we need to add a few extra steps in our procedure.

Download Key from the repository

$ wget -c https://updates.signal.org/desktop/apt/keys.asc

--2017-12-11 22:13:34--  https://updates.signal.org/desktop/apt/keys.asc
Loaded CA certificate '/etc/ssl/certs/ca-certificates.crt'
Connecting to 127.0.0.1:8118... connected.
Proxy request sent, awaiting response... 200 OK
Length: 3090 (3.0K) [application/pgp-signature]
Saving to: ‘keys.asc’

keys.asc                          100%[============================================================>]   3.02K  --.-KB/s    in 0s      

2017-12-11 22:13:35 (160 MB/s) - ‘keys.asc’ saved [3090/3090]

Import the key to your gpg keyring

$ gpg2 --import keys.asc

gpg: key D980A17457F6FB06: public key "Open Whisper Systems <support@whispersystems.org>" imported
gpg: Total number processed: 1
gpg:               imported: 1

you can also verify/get public key from a known key server

$ gpg2 --verbose --keyserver pgp.mit.edu --recv-keys 0xD980A17457F6FB06

gpg: data source: http://pgp.mit.edu:11371
gpg: armor header: Version: SKS 1.1.6
gpg: armor header: Comment: Hostname: pgp.mit.edu
gpg: pub  rsa4096/D980A17457F6FB06 2017-04-05  Open Whisper Systems <support@whispersystems.org>
gpg: key D980A17457F6FB06: "Open Whisper Systems <support@whispersystems.org>" not changed
gpg: Total number processed: 1
gpg:              unchanged: 1

Here is already in place, so no changes.

Download Release files

$ wget -c https://updates.signal.org/desktop/apt/dists/xenial/Release

$ wget -c https://updates.signal.org/desktop/apt/dists/xenial/Release.gpg

Verify Release files

$ gpg2 --no-default-keyring --verify Release.gpg Release

gpg: Signature made Sat 09 Dec 2017 04:11:06 AM EET
gpg:                using RSA key D980A17457F6FB06
gpg: Good signature from "Open Whisper Systems <support@whispersystems.org>" [unknown]
gpg: WARNING: This key is not certified with a trusted signature!
gpg:          There is no indication that the signature belongs to the owner.
Primary key fingerprint: DBA3 6B51 81D0 C816 F630  E889 D980 A174 57F6 FB06

That means that Release file is signed from whispersystems and the integrity of the file is not changed/compromized.

Download Package File

We need one more file and that is the Package file that contains the hash values of the deb packages.

$ wget -c https://updates.signal.org/desktop/apt/dists/xenial/main/binary-amd64/Packages

But is this file compromized?
Let’s check it against Release file:

$ sha256sum Packages

ec74860e656db892ab38831dc5f274d54a10347934c140e2a3e637f34c402b78  Packages

$ grep ec74860e656db892ab38831dc5f274d54a10347934c140e2a3e637f34c402b78 Release

 ec74860e656db892ab38831dc5f274d54a10347934c140e2a3e637f34c402b78     1713 main/binary-amd64/Packages

yeay !

Verify deb Package

Finally we are now ready to manually verify the integrity of the deb package:

$ sha256sum signal-desktop_1.0.41_amd64.deb

9cf87647e21bbe0c1b81e66f88832fe2ec7e868bf594413eb96f0bf3633a3f25  signal-desktop_1.0.41_amd64.deb

$ egrep 9cf87647e21bbe0c1b81e66f88832fe2ec7e868bf594413eb96f0bf3633a3f25 Packages

SHA256: 9cf87647e21bbe0c1b81e66f88832fe2ec7e868bf594413eb96f0bf3633a3f25

Perfect, we are now ready to continue

Extract under tmp filesystem

$ cd /tmp/

$ ar vx signal-desktop_1.0.41_amd64.deb

x - debian-binary
x - control.tar.gz
x - data.tar.xz

Extract data under tmp filesystem

$ tar xf data.tar.xz

Move Signal-Desktop under root filesystem

# sudo mv opt/Signal/ /opt/Signal/

Done

Actually, that’s it!

Run

Run signal-desktop as a regular user:

$ /opt/Signal/signal-desktop

Signal Desktop

Proxy

Define your proxy settings on your environment:

declare -x ftp_proxy="proxy.example.org:8080"
declare -x http_proxy="proxy.example.org:8080"
declare -x https_proxy="proxy.example.org:8080"

Signal