LessPass: sync-less open source password manager
What this seems to be, in essence: password = HMAC(key, website).Why this is bad, compared to an encrypted on-disk key store:1. A password is now ciphertext, not a block of line noise. Every time you transmit it, you are giving away potential clues of use to an attacker.2. The search space for possible passwords is bounded if you know the website. You are subject to key guessing attacks. If your key is short, pure serial guessing will break it fast.3. They don't need any access to you or your stuff, to guess a key. They don't even need access to the server, it can be guessed on an unrelated machine. You don't have the opportunity to detect a break-in and neither does your bank, etc.4. You only have one password for all the sites, really, underneath, and it's your secret key. If it's broken, it's now a skeleton-key and your digital ass is theirs.