gistfile1.py

    def save(self,*args,**kwargs):
        self.response = self.response.lower()
        if not self.expiration:
            self.expiration = datetime.datetime.now() + datetime.timedelta(minutes= int(captcha_settings.CAPTCHA_TIMEOUT))
        if not self.hashkey:
            key_ = unicodedata.normalize('NFKD', str(randrange(0,MAX_RANDOM_KEY)) + str(time.time()) + unicode(self.challenge)).encode('ascii', 'ignore') + unicodedata.normalize('NFKD', unicode(self.response)).encode('ascii', 'ignore')
            if hashlib:
                self.hashkey = hashlib.new('sha', key_).hexdigest()
            else:
                self.hashkey = sha.new(key_).hexdigest()
            del(key_)
        super(CaptchaStore,self).save(*args,**kwargs)