Changing your password should actually change your key

Changing your password after a scare — a phishing email you almost clicked, a device you briefly lost — feels like it should fix the problem. On most apps, it barely does anything. The new password changes how you log in going forward. It does not touch the data that was already encrypted under the old key, because most apps never re-encrypt anything; they just swap the login credential in front of data that was never really tied to that password in the first place.

What an actual rotation has to do

For a password change to mean something in a system where your password genuinely is your encryption key, changing it has to produce a real, new key — and every piece of data has to be re-encrypted under that new key, with the old key destroyed afterward. Anything an attacker copied while the old key was live becomes permanently unreadable to them, because the key that could have unlocked it no longer exists anywhere.

Two modes, for two different situations

Fast rotation — under a second. For routine safety, when you just want a new key with no specific suspicion of compromise. Your vault is re-keyed instantly.

Full rewrite — a few minutes, running in the background. For when you suspect real compromise. Every note is decrypted and re-encrypted under a new key, then the old key is destroyed. This is the mode that matters after a lost device or a password you think leaked.

The full rewrite is also built to survive being interrupted — a dead battery or a crash mid-rotation should never leave your vault half-encrypted under two different keys at once. The new, fully re-encrypted copy is only swapped in once it is completely verified; the old copy is only removed after that. If the process is interrupted, you are still left with one working, fully-intact vault, not a half-finished one.