...I seem to be thinking of Mozilla's "Sync" there.
"your information is encrypted so only you can access it when you enter a Secret Phrase. Firefox puts security as a top priority and syncing is no exception."
I'm not sure how you actually use it.
"It just works. Install Xmarks on each browser you use, and it will seamlessly keep your bookmarks, (and optionally) passwords and open tabs in sync."
(1) Passwords?, and (2) using bookmarks on different -computers- may be a feature of the "Premium" product.
I assume they aren't being foolishly casual about the security of customers' -passwords-.
But maybe you should be looking for a password store with an add-on bookmark facility. (I assume they remember what the passwords are -for-.) There's "LastPass", although, did you hear...... oh dear.