But the short answer is that part of the negotiated key material for the call is used to derive two words from the PGP word list, which are displayed to the user.
If the users then have a conversation about those words and they are the same, then chances are that they have the same key material. In the case of a MITM, they would have different key material, and thus different short authentication strings.
But the short answer is that part of the negotiated key material for the call is used to derive two words from the PGP word list, which are displayed to the user.
If the users then have a conversation about those words and they are the same, then chances are that they have the same key material. In the case of a MITM, they would have different key material, and thus different short authentication strings.