- End-to-end encryption using the Signal protocol to ensure complete privacy.
- Developed by a non-profit foundation and based on open source code.
- Minimal metadata collection compared to other commercial alternatives.
- Advanced features such as temporary messages and identity management using usernames.
If you've ever felt watched while chatting or worried about your personal data ending up in the hands of advertisers, you've probably heard of Signal. This tool isn't your typical messaging app found everywhere; it's become the gold standard for privacy for those who don't trust tech giants.
While it may not have WhatsApp's massive user base, Signal is the preferred choice of security experts and activists. It's not just about sending messages, but about doing so in an environment of maximum confidentiality where not even the app's creators can read what you write or listen to your calls.
What exactly is Signal and what is its origin?
Signal is essentially a free instant messaging platform that prioritizes security above all else. Its history is quite interesting, as it was created by Moxie Marlinspike and Stuart Anderson through Whisper Systems. Originally known as TextSecure for messages and RedPhone for calls, these features were merged into a single app in 2015 under the name we know today.
A key factor in its rise to fame was the recommendation of Edward Snowden , who claimed it was the app he personally used to communicate. Furthermore, its growth skyrocketed during a time of global political tension, when people began seeking refuge from government surveillance and censorship.
Unlike other companies, Signal is managed by the Signal Foundation , a 501(c)(3) nonprofit organization. This means they have no shareholders to pressure or data to sell; they are sustained by donations and the support of figures like Brian Acton, co-founder of WhatsApp, who contributed millions of dollars to ensure the app remained independent.
The technology behind encryption: The Signal Protocol
What makes this app so highly regarded is its technological engine. It uses end-to-end encryption (E2EE), meaning the message is locked on your phone and only unlocked on the recipient's. This Signal Protocol is so robust that even WhatsApp has implemented it in its own architecture.
To achieve this level of security, it relies on three fundamental pillars:
- X3DH (Extended Triple Diffie-Hellman): It allows two people to establish a shared secret key without the Signal server being aware of it. It was recently updated to PQXDH to be resistant to quantum computing.
- Double Ratchet: This algorithm causes the encryption keys to change constantly. Therefore, if someone manages to decrypt a message, they cannot use that information to read previous or subsequent messages, guaranteeing the perfect secret forward.
- Sesame: It is responsible for managing sessions across multiple devices and ensuring that messages arrive in order, even if there are connection problems.
Furthermore, Signal is open-source software . This means that any programmer in the world can review the code on GitHub to verify that there are no backdoors or vulnerabilities. This transparency is what truly builds trust within the technical community.
Main features and operation
If you know how to use WhatsApp, you'll have no trouble getting started with Signal. It's very intuitive: you register with your phone number, set up your profile, and start chatting. However, it offers options that go beyond the basics, such as the ability to blur your face in photos before sending them to add an extra layer of anonymity.
Among its most notable functions we find:
- Ephemeral messages: You can configure the self-destruction of chats from 5 seconds to one week.
- Calls and video calls: Fully encrypted and with support for groups of up to 50 people.
- Mass group chats: It supports up to 1.000 members with detailed administration controls.
- Stories: Visual content that disappears after 24 hours, with strict settings on who can see it.
To protect physical access to the mobile phone, the app allows you to set a security PIN and lock the application using a fingerprint or facial recognition, preventing someone who takes your phone from accessing your conversations.
Comparison: Signal vs. other giants
Many people wonder why bother switching apps if they already have WhatsApp or Telegram. The short answer is metadata management . While WhatsApp (owned by Meta) knows who you talk to, when, and for how long, Signal stores virtually nothing. As proven in court, they only store the registration date and the last time you were online.
Compared to traditional SMS, the difference is enormous. SMS messages are essentially an open book that any operator or government agency can read. Signal, on the other hand, turns communication into a secure tunnel.
If we compare Signal to Threema, we see that the latter is even more extreme by not requiring a phone number for registration. However, Signal wins in practicality due to its enormous user base compared to Threema, making it easier for your contacts to switch to the platform.
Some nuances and security concerns
Not everything is perfect, and there are some points that advanced users often debate. For example, the reliance on Amazon Web Services (AWS) to host its infrastructure could be a theoretical risk if the U.S. government decided to seize the servers, even though encryption protects the content of the messages.
There has also been talk about Intel SGX enclaves, which Signal uses to allow users to find contacts without the company having access to the address book. While efficient, some experts point out that side-channel attacks could compromise certain metadata.
Finally, the Signalgate phenomenon demonstrated that technology can be perfect, but humans are not. When a reporter ended up in a US national security group, it wasn't due to an app glitch, but rather human error in inviting the wrong person. This reminds us that security depends as much on software as it does on common sense.
This app remains the most balanced option for those seeking powerful messaging without sacrificing their privacy, preventing private life from becoming a commodity for advertisers thanks to its non-profit model and transparent architecture.