Signal App Drawbacks ,Challenges , Cons And Things To Know About Signal

Signal Messenger 

In my experience, Signal sometimes doesn't work. Nine times out of ten, it's because the person I'm trying to message uninstalled Signal, or has turned off notifications for the app. If you have Signal as your default SMS Android app, you just tap and hold the send button and you'll see the option to switch to Unsecured SMS. These messages are marked with an unlocked padlock icon, but stay in the thread, which is handy. 

If you're familiar with WhatsApp or Apple Messages, some of Signals quirks might confuse you. For one thing, you won't be able to see the previous chat history when you join a group. That's because those messages can only be read by their intended recipients, which, at the time, didn't include you. 

You'll also periodically see warnings that a contact's Safety Number has changed. The Safety Number, also known as a "fingerprint" in cryptography circles, is a hash of the public key used to secure the messages of a particular chat. When the Safety Number changes, it means that something has occurred that required Signal to generate a new key for your conversation—usually something mundane, like reinstalling the app. But a changing Safety Number is also a warning that someone may be attempting a man-in-the-middle attack on your conversation. You can verify a Safety Number by comparing them to your fellow Signal users, perhaps over a video call. (The number that appears in Conversation Settings>View Safety Number.) If your numbers match, the conversation is secure. 

Screenshot of the Safety Number screen and the disappearing messages screen

This is confusing, and perhaps causes more harm than it helps users secure their messages as it's only useful once everyone understands what a Safety Number is and how to check it.