[guardian-dev] Sending Secure Broadcast Messages with Signal

Nathan of Guardian nathan at guardianproject.info
Mon Feb 13 01:01:21 EST 2017


All credit for my simple script hack is due to the Signal-CLI project,
which works extremely well.

***
https://nathan.freitas.net/2017/02/13/sending-secure-broadcast-messages-with-signal/

I have a created a simple Signal batch sending script (signal-batch.sh),
which works with the fantastic Signal-CLI (Command Line Interface)
project.

Now, you might be asking, why is this needed, or why wouldn’t I just use
a group? Well, there are many cases where a person may want to send an
alert or update message to a large group of people, who don’t otherwise
want to be associated with each other. This is a one-to-many use case,
not a many-to-many. For situations of high risk related to human rights,
activism, living under a police state, or these days, even just being a
U.S. born NASA scientist, it is a very real threat that your phone might
be physically taken from you, and forced to be unlocked. In that case,
anyone in any groups you are in would then also be exposed and put at
risk, as happened in the tragic story of a Mexican activist.

In some cases, you may want to send messages out to 10,000s of people,
for protests, events, concerts, emergencies, and so on. This is a use
cases that goes back to the early, pre-Twitter TXTMob and RNC2004
systems I was involved in , except we were just using plain old SMS
then, which was expensive and risky. Now, you can do this with fully
encrypted messages, sent freely anywhere on the globe, right from your
laptop. Neato!

Okay, so how does the script work? Here’s a quick run-down with
instructions for any Linux or MacOS system. (This can work for Windows,
but someone needs to rewrite the script as a BAT script).

Download Signal-CLI and unpack it somewhere
Download the signal-batch.sh script and put it into the “bin” folder for
Signal-CLI
Create a text file with all of the numbers you want to send to, one per
line, with country code (+12125551212)
Open a terminal, and follow, the excellent signal-cli readme
instructions on how to register your number (or a new, clean number)
with Signal
Once you complete the registration and verification, you are ready to
run signal-batch.sh!
In the terminal type > ./signal-batch.sh to see the usage info below
usage: ./signal-batch yourSignalNumber yourBatchList “Your message goes
here!”
example: ./signal-batch +12125551212 mygrouplist.txt “This is the
broadcast message you requested!”

Before I go, I must state this: DO NOT ABUSE THIS SCRIPT FOR SPAM, DoS
OR OTHER MALICIOUS PURPOSES. I am sure your Signal account will be
shutdown if you do, and the “this is why we can’t have nice things” bad
karmic spirits will reign down on you.

Finally, if you are promoting the use of Signal to high risk
communities, please read some of these excellent guides below and making
it as safe as possible:

EFF Surveillance Self Defense: Signal iOS Guide  Signal Android Guide
The Intercept: Security Tips Every Signal User Should Know
DeepDotWeb: Tips for using Signal Safely as possible

-- 
  Nathan of Guardian
  nathan at guardianproject.info


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