access_tokenon Hivesigner are just simple message signed with Hive private keys and encoded in base64u. User Interface (UI) gives you easy way to handle your authorities and keys.
access_tokenis being sent from those applications to Hivesigner API, the API then verifies that token, if it's valid, transaction is broadcasted using @hivesigner posting key.
@ecency.appaccount to do posting operation on
@hivesignerto do posting operation on