Add an initial seed

[shauncroton]

I have not had a great play with this but is seems to me it lacks an initial seed value.
For example if I want both my and my wife's phone to both give back the same hash for say "amazon.com/password" and for no-one else to be able to generate same hash I would need to enter a common seed on both installations that would participate in the hash.

[phw]

True in general. But as this is just a implementation of pwdhash and the goal was to be compatible with that I won't introduce any changes not available in the original. The implementation should still work with all the pwdhash plugins that are available to desktop browsers.

I had already thought of extending this app into a more general password management solution, based on the pwdhash idea but extending it. One issue is of course the lack of browser extensions in that case. And more importantly my lack of time :)

[quassy]

@phw Do you have any drafts for this? I'd be interested in collaborting to create a scrypt, Argon2 or bcrypt based solution with a user configurable salt and flexible iteration number (maybe something like 2^currentyear so hashes depend on the year they are created and people are motivated but not forced to update every year).