Where does a signal come from

WhatsApp alternatives under the microscope: what can Signal do?

Most of us use WhatsApp to communicate with friends, family and maybe colleagues on a day-to-day basis. But there are also safer and better messengers out there. We want to present these in more detail in a series. Today: signal.

Signal is available free of charge for iOS and Android and as a desktop version for Mac, Windows and Linux. You read a lot about the fact that experts consider Messenger to be one of the safest alternatives to WhatsApp - if not the safest short message service of all.

We take a closer look at the reasons for this and whether Signal is really as safe as is often claimed.

Edward Snowden recommends Signal

Signal is the news app that Edward Snowden also uses - the US NSA whistleblower made it public on Twitter in November 2015.

Snowden has lived in exile in Russia since August 2013 and is preparing the publication of his memoirs, which he plans to publish on September 17, 2019. He was stranded there after leaking confidential documents to journalists about wiretapping practices by the US secret service NSA and other services in 2013.

He then fled from Hawaii to Hong Kong in order to fly from there to Moscow. The Americans meanwhile withdrew his passport, so that he could not get any further after a stopover in the Russian capital.

Today Snowden appears regularly on social networks like Twitter and comments on political developments. His current Russian residence permit will run until the beginning of 2020.

Signal is safe

It should instill trust that someone like Snowden is using Messenger. And there are reasons for that: With Signal, users can send encrypted messages, photos and videos and also make secure calls.

All texts, data and calls are always end-to-end encrypted. According to this, Signal should neither read your messages nor see your calls - like no one else.

WhatsApp now also encrypts end-to-end messages. However, WhatsApp did not develop this encryption itself, but in cooperation with Open Whisper Systems, the manufacturer of Signal.

Open Whisper Systems publishes the source code - i.e. the actual program for the application - freely accessible to all people on the online service Github. This step increases security, because thousands of developers can check this source code and publish changes themselves or send them to Signal directly.

This can close a lot more security gaps. After all, people outside the company can and should always be aware of this.

Signal is trustworthy

The end-to-end encryption of WhatsApp is based on the technology of Open Whisper Systems. What we don't know is whether WhatsApp might have built in its own back door.

WhatsApp publicly admits on its blog to work with other Facebook companies and to share information with them "so that they can provide WhatsApp services in the areas of infrastructure, technology and systems".

In 2016, the Messenger proved that Signal is trustworthy when it comes to handling data: An order from a US federal district court in the state of Virginia forced Open Whisper Systems to disclose user data and also to maintain absolute secrecy.

With the help of the American Civil Liberties Union (ACLU), however, the company succeeded in lifting the obligation to maintain silence and making some details public.

The authorities therefore requested data from two alleged users, although only one of them had actually used the signal. They wanted access to their name, IP address and the complete account history.

There was also interest in the payment information and other profiles linked via a tracking cookie. However, Open Whisper Systems only had two pieces of information: the time at which the account was created and when it last connected to the Signal servers.

Signal could not hand over any further data because the messenger did not have any further data apart from the telephone number.

Open Whisper Systems collects as little data as possible

Communication via signal is completely encrypted. So your data really only stays on your device. That is why experts like Snowden are happy to recommend the messenger to others.

This is possible because the company doesn't even have to rely on making money with user data. That looks different with the Facebook subsidiary WhatsApp, of course.

Signal is financed exclusively through "grants and donations", as it says on the website. Incidentally, Wikipedia does the same as a free encyclopedia.

The messenger in practice

If you downloaded the app from the Apple Store or the Google Play Store, you have to register your device with your phone number. You will then receive a code by SMS that you enter in the application. This is how you confirm that your phone number really belongs to you.

Then enter your name and optionally choose a profile picture. You allow the app to access your contacts from the phone book and your photos and videos if you want to send them.

Each user is assigned a unique key made up of letters and numbers. As soon as you exchange the first message with a new contact, this fingerprint is saved.

If you use a new mobile phone or reinstall the app, this key will change. Signal then notifies the person you are talking to. The digital fingerprint can also be verified using a barcode that you scan with another smartphone.

For whom Signal is not suitable

Signal masters all the basic functions of a messenger. We can send text and voice messages, photos, videos and GIFs. We can also create encrypted group chats, make phone calls and make video calls.

In terms of functionality, WhatsApp is also one step ahead: There are no status messages on Signal. Video calls with several people at the same time are also not possible.

Another point of criticism: Android users can easily create chat backups. This is currently not possible with an iPhone - not even with an iCloud or iTunes backup.

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In any case, it is true that Signal is one of the most secure messengers on the market. In contrast to the paid Threema, the application is also free of charge, as mentioned at the beginning.

However, the messenger cannot be used without a phone number. Signal is therefore not a WhatsApp alternative for you if you want to keep your number secret.

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