Signal

I decided to try Signal today. The security and privacy features are probably its best selling point as well as it being FOSS. However, it’s got some rough edges that you should probably be aware of before deleting all your other messaging accounts.

First, here’s a little background. I’m kinda old so I’ve used a fair amount of computer mediated communication systems over the years. I started with instant messaging on AOL in the early 1990s and continued using the standalone service (AIM) for awhile as well. Toward the late 1990s I had fun with ICQ. In the 2000s I picked up IRC and Lily, which is a chat service created by some RPI developers. I use IRC and Lily primarily in a terminal, which fits my usage patterns for other things. I ran my own XMPP (jabberd) server for awhile and was able to talk to folks who used Google Talk until Google decided to kill their XMPP S2S interface and re-invent the product as Google Hangouts. I also picked up Facebook Messenger as well because a few of my friends use it. I tried out Telegram in early 2020 but didn’t end up using it for anything. SMS is also there for correspondence with one or two folks as well as all those insecure 2FA things and a whole lotta spam.

For work, I’ve used Microsoft OCS/Lync at two jobs as well as Amazon Chime and Slack.

I’ve never used WhatsApp or SnapChat.

Here’s my current state of my non-work messaging:

  • IRC – Mostly idling and periodic chats
  • Lily – Mostly idling and periodic chats
  • Facebook Messenger – Daily chats
  • Google Hangouts – Daily chats
  • SMS – Daily spam, some chat, and horrible 2FA

Google has made it clear that they are going to kill Hangouts or at least change it into something I won’t like, so I’ve decided I will use Hangouts until it no longer works. I won’t be using any future chat products by Google.

With the pending (although it now seems delayed?) WhatsApp ToS change and the increasing popularity of Signal, I figured I’d give it a go.

Account creation was easy but used my phone number as my identity. This rubbed me the wrong way because I would like to think phone numbers are ephemeral. It’s not supported to change phone numbers, currently. I started with the Android app, created my PIN (4 digits or optional alphanumeric), and was off to the races.

The app found about a dozen or two contacts from my address book that are already using signal, including some good friends and family members. This was encouraging.

I was away from my Linux workstation and using my MacBook so I installed the macOS app and activated it using a QR code read by my phone. Pretty easy so far. I then later went to install the Linux app on Debian, and ran into some issues.

While Signal’s site indicates that it provides binaries for 64-bit Debian-based distributions I had to add an APT source that referenced the xenial distribution, indicating it was Ubuntu-centric. Broadcasting support for Debian-bases distributions and then being centered around Ubuntu is a pet peeve of mine. Anyway, I use Debian testing, which is a rolling snapshot of the next stable distribution (bullseye, at the moment) and I ran into dependency problems when trying to install signal-desktop:

The following packages have unmet dependencies:
signal-desktop : Depends: libappindicator1 but it is not installable

Well, that’s nice. According to a bug report this is due to libappindicator1 being deprecated. The workaround was to change sources to sid and try the install again, which worked. I, of course, changed my sources back to testing. I’m sure things will break again in the future.

The Signal app for Linux looks like it’s nothing more than an Electron-style wrapper that uses Chrome or Chromium under the hood:

(destiny:15:56:PST)% ps xf|grep signal-desktop|cut -b -$COLUMNS
1386976 ? SLl 1:43 | _ /opt/Signal/signal-desktop --no-sandbox
1386978 ? S 0:00 | _ /opt/Signal/signal-desktop --type=zygote --no-sandbox
1387002 ? Sl 0:15 | _ /opt/Signal/signal-desktop --type=gpu-process --field-t
1387008 ? Sl 0:00 | _ /opt/Signal/signal-desktop --type=utility --field-trial
1387023 ? Sl 9:21 | _ /opt/Signal/signal-desktop --type=renderer --no-sandbox
1479371 pts/22 S+ 0:00 _ grep --color signal-desktop

Yeah..

(destiny:15:58:PST)% ls -a1 /opt/Signal
.
..
chrome_100_percent.pak
chrome_200_percent.pak
chrome-sandbox
crashpad_handler
icudtl.dat
libEGL.so
libffmpeg.so
libGLESv2.so
libvk_swiftshader.so
LICENSE.electron.txt
LICENSES.chromium.html
locales
resources
resources.pak
signal-desktop
snapshot_blob.bin
swiftshader
v8_context_snapshot.bin
vk_swiftshader_icd.json

Meh, I don’t really care but I’m a little bit disappointed, especially because there is no actual web interface offered. It only takes up 332 MiB RSS, which is nice. It could be worse!

There’s a Pidgin plugin that I need to try. It looks like it has a hard dependency on signald to do anything, which I’m not familiar with at all. More things to do later, I suppose.

So, everything was mostly peachy, right?

It was until I decided to fire up signal on my 2nd phone, an iPhone Xs. Yes, I carry two phones because iOS offers some things that Android doesn’t and vice versa. I can’t decide which platform is best for me so I have selected both.

My iPhone has a different phone number, of course, so I plugged in my original phone number when starting up the iOS Signal app. Everything seemed to work fine until I realized that the Signal app on my other devices and Android phone started kicking out API errors. After trying to figure what was going on I found the page that indicates that more than one phone is not supported.

Huhwha? While this is not a deal-breaker I also realized that Android tablets are not supported either. I don’t get it, why can’t Signal on my iPhone be activated the same way the macOS and Linux clients were activated? I have a feeling the answer is security-related, but I can’t actually figure it out.

Lastly, to finish this up, I was curious who hosted Signal. I tcpdump’ed some DNS requests from a fresh Wi-Fi connection from my Android phone to see the following:

16:09:00.217072 IP 10.3.6.114.48167 > 10.3.5.1.53: 7640+ AAAA? textsecure-service.whispersystems.org. (55)
16:09:00.260375 IP 10.3.5.1.53 > 10.3.6.114.48167: 7640 0/1/0 (140)
16:09:00.261707 IP 10.3.6.114.25681 > 10.3.5.1.53: 18696+ A? textsecure-service.whispersystems.org. (55)
16:09:00.389951 IP 10.3.5.1.53 > 10.3.6.114.25681: 18696 2/0/0 A 76.223.92.165, A 13.248.212.111 (87)
16:09:00.697416 IP 10.3.6.114.39256 > 10.3.5.1.53: 21129+ AAAA? storage.signal.org. (36)
16:09:00.843944 IP 10.3.5.1.53 > 10.3.6.114.39256: 21129 4/0/0 AAAA 2001:4860:4802:34::15, AAAA 2001:4860:4802:38::15, AAAA 2001:4860:4802:32::15, AAAA 2001:4860:4802:36::15 (148)
16:09:00.845337 IP 10.3.6.114.16859 > 10.3.5.1.53: 41372+ A? storage.signal.org. (36)
16:09:00.882592 IP 10.3.5.1.53 > 10.3.6.114.16859: 41372 4/0/0 A 216.239.34.21, A 216.239.36.21, A 216.239.38.21, A 216.239.32.21 (100)

This mostly matches up with what’s detailed here regarding firewall settings for Signal. It looks like *.signal.org and *.whispersystems.org are the main domain names. Right now, textsecure-service.whispersystems.org. is not dual-stacked, which means it won’t work in an IPv6-only environment. Also, looking up the addresses that the two names resolve to gives me:

(destiny:16:13:PST)% for i in 76.223.92.165 13.248.212.111 2001:4860:4802:34::15 2001:4860:4802:38::15 2001:4860:4802:32::15 2001:4860:4802:36::15 216.239.34.21 216.239.36.21 216.239.38.21 216.239.32.21; do ipin ${i}; done
4 Address: 76.223.92.165
4 PTR: ac88393aca5853df7.awsglobalaccelerator.com.
4 Prefix: 76.223.92.0/24
4 Origin: AS16509 [AMAZON-02, US]
4 Address: 13.248.212.111
4 PTR: ac88393aca5853df7.awsglobalaccelerator.com.
4 Prefix: 13.248.212.0/24
4 Origin: AS16509 [AMAZON-02, US]
6 Address: 2001:4860:4802:34::15
6 PTR: any-in-2001-4860-4802-34--15.1e100.net.
6 Prefix: 2001:4860::/32
6 Origin: AS15169 [GOOGLE, US]
6 Address: 2001:4860:4802:38::15
6 PTR: any-in-2001-4860-4802-38--15.1e100.net.
6 Prefix: 2001:4860::/32
6 Origin: AS15169 [GOOGLE, US]
6 Address: 2001:4860:4802:32::15
6 PTR: any-in-2001-4860-4802-32--15.1e100.net.
6 Prefix: 2001:4860::/32
6 Origin: AS15169 [GOOGLE, US]
6 Address: 2001:4860:4802:36::15
6 PTR: any-in-2001-4860-4802-36--15.1e100.net.
6 Prefix: 2001:4860::/32
6 Origin: AS15169 [GOOGLE, US]
4 Address: 216.239.34.21
4 PTR: any-in-2215.1e100.net.
4 Prefix: 216.239.34.0/24
4 Origin: AS15169 [GOOGLE, US]
4 Address: 216.239.36.21
4 PTR: any-in-2415.1e100.net.
4 Prefix: 216.239.36.0/24
4 Origin: AS15169 [GOOGLE, US]
4 Address: 216.239.38.21
4 PTR: any-in-2615.1e100.net.
4 Prefix: 216.239.38.0/24
4 Origin: AS15169 [GOOGLE, US]
4 Address: 216.239.32.21
4 PTR: any-in-2015.1e100.net.
4 Prefix: 216.239.32.0/24
4 Origin: AS15169 [GOOGLE, US]

That’s some nice big tech right there! Ah well, at least Signal is end-to-end encrypted so I don’t have to care who or what is in the middle.

I’ll keep an eye out for multi-phone support as well as IPv6 server support and the ability to change phone numbers in the future. For now, Signal seems like a clear privacy-centric alternative to other things like WhatsApp, FB Messenger, and Google Hangouts (and whatever will replace it).

Leave a Reply

Your email address will not be published.