How can I change a Django form field value before saving?

If you need to do something to the data before saving, just create a function like:

def clean_nameofdata(self):
    data = self.cleaned_data['nameofdata']
    # do some stuff
    return data

All you need is to create a function with the name **clean_***nameofdata* where nameofdata is the name of the field, so if you want to modify password field, you need:

def clean_password(self):

if you need to modify passwordrepeat

def clean_passwordrepeat(self):

So inside there, just encrypt your password and return the encrypted one.

I mean:

def clean_password(self):
    data = self.cleaned_data['password']
    # encrypt stuff
    return data

so when you valid the form, the password would be encrypted.