Part 2 of 3 of the account archive agreed in #1198. When the admin turns on
"Account List Backup: Passwords" (off by default), saving the list offers to
include the passwords of the accounts signed in here with a plain password.
They are encrypted in the browser together with the list. On restore, those
accounts are signed in to in the background, one by one, without leaving the
active account; a refused password leaves the account waiting for a sign-in by
hand, as before. OAuth and TOTP accounts are saved without a password.
Users with several accounts can save the list of accounts in their browser
(address, server, label, colour) on the webmail server and bring it back on
another device. The list is encrypted in the browser with a password the user
chooses (PBKDF2-SHA-256, 600,000 iterations, AES-256-GCM, owner bound as
additional data); the server stores only the envelope, one file per owner
under SETTINGS_DATA_DIR/account-archives. No mailbox passwords are included.
Off by default behind the admin feature gate accountArchiveEnabled, pinned
off in Lite. Every method of /api/account-archive needs a session cookie of
the owner, matched without regard to case, whose credential is checked
against the mail server on each call; listing included.
Restored accounts this browser lacks are listed as awaiting sign-in: they
survive a reload, and opening one leads to the sign-in form with the address
filled in. Accounts already present get their archived label and colour.
Linus Rath
lucamzanon