On Signal you're encouraged to verify out-of-band (such as in person) with the "safety number" which allows users to verify each other's keys to prevent a man-i

On Signal you're encouraged to verify out-of-band (such as in person) with the "safety number" which allows users to verify each other's keys to prevent a man-in-the-middle attack. This way you'll notice if the initial key exchange has been compromised.