Why do they recommend the user to verify the 60 digit code in person or via other medium of communication.
How is the security code generated and work on Signal and Whatsapp Messanger?
Cryptography Stack Exchange is a question and answer site for software developers, mathematicians and others interested in cryptography. It only takes a minute to sign up.Sign up to join this community
Here is a detailed blog post about the safety numbers: https://signal.org/blog/safety-number-updates/
They are unique per conversation and basically consist of hashes of your and your contact's public long-term key.
You should compare them if you want to be sure that there is no man-in-the-middle.