Signal App Security has been thought to be the most private way to send messages in the past. As a result, they had to develop some ideas that were not popular with everyone. Are Signal and the other people in the group still safe?
First, you need to know the difference between cryptography and how it’s done in the real world. Cryptography is mostly math. Implementation is when cryptography is used in the form of computer code. Another way to think about this is the difference between theory and real life. You can think of cryptography as a theory and implementation as a way to put it into use.
The cryptography is called the “Signal protocol in the Signal app.” The Signal is a safe way to do things. WhatsApp, Skype, Google’s RCS, and even Facebook Messenger are all based on it.
The controversy comes from how the Signal protocol is used on the Signal messaging app. Some of them:
Using Phone Numbers
Signal and WhatsApp both use phone numbers as user account IDs, and this is how they work. To sign up for Signal, you need to give us your phone number to connect.
Putting your phone number out there isn’t something everyone is comfortable with. In most countries, you can’t get a mobile phone number without your real name. Every mobile phone number must be checked to make sure it is real. Even if you don’t need to show your ID (in the US, I think), you still need contact information like your email address. Once you give your email address, your anonymity is as good as the email service provider’s anonymity.
Another thing you need to do to activate your Signal app account is getting a text message (or get a phone call) from it. This means you need to turn on your cell phone. When you turn on your cell phone to get the text message, it will communicate with radio towers that can help you figure out where you are.
Syncing the User’s Social Graph With Signal’s
It would be ideal if messaging apps didn’t store any of your contacts’ phone numbers on their servers. This means that if the messaging app doesn’t have the phone numbers of the people you want to connect with, it can’t figure out your social graph. WhatsApp is the subject of a lot of debate.
Now, let’s say that Signal enables you to sign up with a user name that you come up with rather than your phone number. Let’s say that you have built up your social graph over time in the app. If you lose your phone, reinstall the app, or get a new one, your social graph will be lost. You can’t store your contacts’ Signal user names in your phone’s address book as a separate entry field.
The most private way to solve this is to encrypt your social graph on your phone before sending it to the cloud (the messaging app’s server). What is the question? Which encryption key should you use to protect your social graph? In this case, you can’t use the same key to encrypt your messages. If you lose your phone or get a new one, the key will be lost. Lost keys mean that you can’t open your social graph on the new phone. So, the only way to get the key is to come up with a password just for this purpose.
This is not a good idea because we already have too many passwords to remember. If you forget your password, you will lose all your friends and family. So, most people will come up with easy-to-remember passwords that are very weak when it comes to cryptography, so this will happen.
The Signal came up with a unique way to solve this problem. To understand this, look at your ATM PIN. It has a 4–6 digit number in it. Your ATM PIN is fragile when it comes to cryptography. But if you enter your ATM PIN wrong a certain number of times, the ATM will eat your ATM card.
In the same way, Signal made it so that your Signal PIN is needed to get the required cryptographic secret to decrypt your social graph (the cryptographic secret, in conjunction with your Signal PIN, is used to encrypt your social graph). If you want to get the cryptographic secret, you need a special computer inside Intel’s CPU called the “SGX.” Even Signal can’t get it. The most important thing to know is that if you give the SGX the wrong Signal PIN, it won’t give you the cryptographic secret. In the SGX, if you give it the incorrect Signal PIN too many times, it will lock you out of that secret. You can read about how Signal does this here.
To cybersecurity purists, this feature is a big no-no. They say that no user information should be sent to any servers. Period. You can also make sure that your Signal PIN is cryptographically safe by using the alpha-numeric option to enter a long and random text like this:
Signal Closes Source?
Then there’s the claim that Signal is no longer open-source. This isn’t 100% true. They don’t make all but some of their server software. The app itself is still free to use. This has something to do with spam. Signal has written an article that explains why some parts of their server software must be closed-source to fight spam. The following is my summary if you don’t have time to read the whole thing.
In traditional email spam-fighting, spam filters need to know about the content of emails to learn how to recognize spam (using AI machine learning). That said, Signal is built to keep the content of your messages private, so even Signal itself can’t read your messages. In this way, traditional spam filtering methods that use AI machine learning is not available to Signal. To find spam, they need to know how spammers act. Signal’s servers are made to look at how people act to see if a message is a spam or not. Even though spammers might be able to figure out what Signal thinks is suspicious, they can change their behavior to get around Signal’sSignal’s spam detection. Signal closed the source code of that part of their server because they didn’t want people to see it.
Everyone who wants to be a cybersecurity purist says that everything must be open source. Period.
What Links WhatsApp and Signal?
In 2017, Brian Acton left WhatsApp to help start a new foundation called the Signal Foundation. This foundation is the group that makes the Signal messaging app. Some people aren’t happy with that.
Are You the Product, Since Signal Is Free?
The Signal is a free app that lets you talk to others through text. But does that mean that their customers are their primary source of income, too?
A business called Signal isn’t really what it seems to be. It is set up as a non-profit organization. It gets money from people who want to help with its operations and services.
Cryptocurrency Support in Signal
Signal added a cryptocurrency feature to their app in the last few months. Users can send and receive payments for the cryptocurrency Mobile Coin through the Signal text messaging app.
A lot of people don’t like this.
Bitcoin is not private, contrary to what most people think. Every Bitcoin transaction is recorded on the blockchain, a public ledger. If your Bitcoin public key is ever linked to your name, all of your past and future transactions will be public. Mobile Coin, on the other hand, is meant to be private. If you use Mobile Coins, you won’t track them like you can with Bitcoins. As Bruce Schnier said, this is why,
This is a terrible idea. No, it’s not just the bloated secure communications app. Not only is blockchain stupid. The Signal isn’t even tied to a specific blockchain currency. A cryptocurrency is an end-to-end encrypted app that muddies the product’s morality and invites government investigation and regulation from the IRS, SEC, FinCEN, and probably the FBI.
And I see no reason to. In some cases, secure communication and secure transaction apps can be from the same organization. Encryption is already in jeopardy. The Signal is our best app. If it’s combined with a cryptocurrency, it means the whole system dies.
End-to-end encrypted messaging itself is a risk to the government. Adding a specially-designed private cryptocurrency service makes it easier for the government to attack.
So, Signal Is Still Safe Now?
When you look at Signal’sSignal’s decisions, you can see them in two ways.
If you wear the hat of a cybersecurity or privacy purist, you will be uncomfortable with what Signal does. It might not be worth it for some of them.
People who care about cybersecurity and privacy will be happy with your product, but most people won’t be able to use it. This is important to keep in mind. If most people can’t use it, it won’t become famous. Also, if your product makes cybersecurity and privacy purists happy, it will become a haven for bad actors, criminals, and abusers who want to do bad things. If that happens, the government will pay attention and stop it.
Understanding the reasoning behind their decisions will help you decide whether Signal is still safe for you. You will also have to decide for yourself if there is anything about these decisions that isn’t safe to keep using. If you want to have an app that is easy to use and can be found in the official app store, you can’t be a purist. There will be some compromises and regulatory oversight. If you don’t care about these things, Signal is still a good choice for a phone.
Of course, there are messaging app projects that try to appease purists (e.g., Keybase.io). However, due to philosophical differences, these projects frequently suffer from usability, performance, slow development progress, and infighting issues. As a result, they will always be on the fringes.