Hi Erik,
This looks promising. I like how the validators can be chained and the
whole simplicity of the patch.
Here's some comments I also left on the PR;
1. I think the settings should be name AUTH_PASSWORD_VALIDATORS since
it's being use by the auth contrib app;
2. I would avoid mixing the backend and validators terminology. e.g
`get_password_validators` sounds like a more consistent name then
`get_password_backends`;
3. I would either make `help_text` a property of rename the method to
`get_help_text`.
Like Raphael I also think we should avoid introducing a new way of defining
settings. I suggest we use a list of path to instances of password
validators instead:
AUTH_PASSWORD_VALIDATORS = [
'django.contrib.auth.password_validators.min_eight_chars_validator',
]
And document MinimumLengthPasswordValidator so you can create your own
instances and point the setting to it.
Simon
Le dimanche 8 mars 2015 10:48:00 UTC-4, Erik Romijn a écrit :
>
> Hello all,
>
> I've taken another stab at 16860[1]: having a password validation/policy
> in Django. I've made an initial simple PR[2] to show the approach I'd like
> to use - no tests or documentation yet, the example validators are not very
> nice, possibly bad naming, etc. But this should be sufficient to show how I
> would like to tackle this. There's quite a few decisions to take,
> influencing the later possibilities, which I'll try to outline below.
>
> Users choosing awful passwords is a serious security issue. Although
> password validation can only go so far - especially to the extent that we
> can implement in Django itself - to me it seems part of our responsibility
> in helping Django developers to build safer websites.
>
> First, let me briefly describe my approach: we add a new setting to define
> zero or more password validator classes. Optionally, a class can be
> provided with custom arguments to it's constructor. Each validator class
> has a help_text() method and a validate(password, user) method. The former
> produces a translatable sentence to be included in the form field's help
> text. The validate method validates a certain password, optionally taking
> the context of a user into account and passes its judgement on the
> password. If a validator considers a password insufficient, it raises a
> ValidationError.
>
> This is tied to the validation and form field setup in SetPasswordForm and
> AdminPasswordChangeForm. An obvious choice seems to be to tie this to
> User.set_password(). However, I intentionally did not include that step, as
> I feel this validation should primarily take place on the user frontend
> site with forms. This mirrors the way we typically handle this in Django.
> Should someone feel different, and want to tie this to set_password() as
> well, this is possible with a custom user object. Tying this validation
> into any other place is also trivial: just adding a single line.
>
> I decided not to go for standard Django validators, as I felt this would
> offer insufficient flexibility and configurability - as was already raised
> in previous discussions on this issue.
>
> In the ticket, Shai described a few particular goals for this feature:
>
> - Informing the user of the various password requirements: this is
> possible by each validator providing a description, which can be dependent
> on it's configuration, of it's requirements. Independent sentences from
> different validators are now concatenated, an approach which will not
> always yield the prettiest language.
> - Allowing policies to chain together smoothly: multiple validators can be
> run sequentially, stopping after the first failure.
> - Provide flexibility for complex requirements (some may include their own
> models): this is entirely possible within the design.
> - Backwards compatibility: the default setting is to have no validators,
> which means no change and no modifications in help text. I do suggest we
> include some reasonable defaults in the standard project template.
> - Javascript validation assistance or HTML5 support: not implemented
> currently, but this could be added in a similar way as help texts.
> - Prevent using email, username or other user attributes as (part of)
> passwords: where possible, the user object is passed to the validator.
> There's a (not pretty) example of this in the PR.
> - Prevent reuse of old passwords: it is possible in the design for a
> validator to store all passwords it saw. I have doubts on whether this
> would be a good approach though.
>
> So I think this design makes it simple to have sane defaults for new
> projects, extensive configurability while keeping simple scenarios simple
> to configure, and easy extensibility with third party password validators
> (zxcvbn comes to mind). I'd love to hear any feedback and ideas you may
> have.
>
> Erik
>
>
> [1] https://code.djangoproject.com/ticket/16860
> [2] https://github.com/django/django/pull/4276
>
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