Is this specific to the Mastodon implementation or is it in the ActivityPub protocol specification?
I didn't know Mastodon implemented a built-in way to verify your account, this is great news. For those who want to verify on other networks: you can use keyoxide.org for that - however it is a rather cumbersome process. But I know that the developer (@yarmo@fosstodon.org) is aware of it and aim to make it more easier to verify different accounts on different platforms.
Is this specific to the Mastodon implementation or is it in the ActivityPub protocol specification?