class someInputForm(forms.Form):
    def __init__(self, protectedFields, *args, **kwargs):
        super(someInputForm, self).__init__(*args, **kwargs)
        for key, value in protectedFields.iteritems(): # For Python 2.6 just use items()
            self.fields[key] = forms.CharField(initial = value, widget = forms.HiddenInput())
            item = value
            def cleanthis(item = item): # Sometimes you have to decide if you love Python for this or not ;-)
                return item
            setattr(self, 'clean_%s' %(key), cleanthis)

# Example:
hiddenData = {'action': 'add', 'hash': '05ff2cba6e002b09288a99701ad5cfc9'}
form = someInputForm(hiddenData)