It shouldn't be hard
Fring should just have the real password a secret, and let the user have a meta-password which unlocks the single real Fring password to unlock the various protected passwords.
When the Fring user wants to change his Fring password (the meta-password) the real secret password doesn't change but is just re-encrypted with the new meta-password.
SSH public keys are often protected in a similar way.
I expect that all Fring uers will need to create a new account ^H^H^H^H^H^H^H upgrade their account to use the new secure "you can change your password" feature.
Sam


