> One case although, is to keep a simple password you'll remember to access your client-side encrypted cloud backups of your password manager db. Otherwise you could end up in a case where you've lost all of your passwords and your shit out of luck when you lose your computer and your local backup.

The problem is that if you can remember a password, then a computer can guess it, and if you store something in the cloud then a computer can perform offline attacks all day long. And as time goes by, those offline attacks only get faster. This is one of the reasons that Mozilla's new Firefox accounts & sync system are insecure and unsuitable for storing passwords or other private data.

Sure, if it's an epic passphrase run through PBKDF2, bcrypt, scrypt or argon with a truly evil work factor (like, on the order of hours), then _maybe_ it's suitable for securing a backup of the keys to one's kingdom. Maybe.

Better, I think, is to encrypt the backup with a secure key, then encrypt the secure key with a memorable password, then use k-of-n secret sharing to give shares of the encrypted key to some number of trusted people. Up to k-1 of those people may disclose his share without endangering the encrypted secret, and if k do disclose it then it is still protected by the memorable password.

The problem is that in a world of cloud backups, a mistake tomorrow can endanger yesterday's backups.

>The problem is that in a world of cloud backups, a mistake tomorrow can endanger yesterday's backups.

This. This is the big problem with password managers. If your master password ever get compromised, you can't effectively change it in all backups and replicas, new and old, local and cloud, on various media supporting reliable wiping or not. You either can't track or can't control them. Even periodic rotation of master password is almost pointless.

I keep a note in the safe at work providing me with sufficient hints about my password manager password to be able to recreate it - without it being something that helps anybody else (think something along the lines of "every third word of the first two stanzas of that poem my second girlfriend loved").

I have the encrypted file synced across two phones, an iPad, a work machine (including it's on-site and off-site backups) two home machines (including a Dropbox account, a Time Machine networked backup drive, and a weekly rsync of the Time Machine backup to off-site storage).

I did once leave a bag containing my laptop, and my 60G iPod containing my laptop's only backup (including my only copy of my password manager file and a fair bit of confidential work-related source code) under an outside table at a cafe right before closing time. I spent a sleepless night worried as hell about it, but a friendly and familiar waitress who kind-of knew me had found it and stashed it behind the counter with a note to her manager describing me, so I got it back the next morning. That made me a) very happy, and b) somewhat more careful and paranoid about my backup and password storage habits...

It would be interesting to see a Shamir's Secret Sharing implementation applied to a bunch of multi-factor authentication devices.

Keep it simple but long, see famous relevant xkcd "correct horse battery staple" . My randomly generated passwords are usually 16 characters, but my password manager master is 40+ chars, and much easier to remember.