how to use django's registration field(s) to custom table
from django.contrib.auth.models import User
from django.db.models.signals import post_save

class Token(models.Model):
  user = models.OneToOneField(User)
  api_key=models.CharField(max_length=50)


def create_user_token(sender, instance, created, **kwargs):
 if created:
   profile, created = Token.objects.get_or_create(user=instance)

#this will definitely not work because i have no field name api_key on form
post_save.connect(create_user_token, sender=User)

#password=posted from django-registration form as i have used django-registration
 digest = hmac.new('Secret', password, hashlib.sha256).hexdigest()

from django import forms
from registration.forms import RegistrationForm
from django.utils.translation import ugettext_lazy as _
from registration.models import RegistrationProfile

attrs_dict = { 'class': 'required' }

class RegistrationFormEx(RegistrationForm):
  cell_phone = forms.CharField(widget=forms.TextInput(attrs=attrs_dict))

import hashlib
import hmac
from django.db import models
from django.contrib.auth.models import User
from registration.signals import user_registered
from userInfo.forms import RegistrationFormEx


class ExProfile(models.Model):
   user = models.ForeignKey(User, unique=True)
   cell_phone = models.CharField(max_length=200, blank=True)
   api_key=      models.CharField(max_length=200, blank=True)

   def user_created(sender, user, request, **kwargs):
      form = RegistrationFormEx(data=request.POST)
      digest = hmac.new(str(request.POST['password1']), str(request.POST['username']), hashlib.sha256).hexdigest()
      new_user = User.objects.get(username=request.POST['username'])
      //here I have added api_key hash algo, you can change it
      new_profile = ExProfile(user=new_user,cell_phone=request.POST['cell_phone'],api_key=digest)
     new_profile.save()
     return new_user

  user_registered.connect(user_created)

from django.conf.urls import patterns, include, url
import registration.backends.default.urls as regUrls
from registration.views import register
from userInfo.forms import  RegistrationFormEx


urlpatterns = patterns('',
url(r'^accounts/register/$', register, {'backend': 'registration.backends.default.DefaultBackend','form_class': RegistrationFormEx}, name='registration_register'),
(r'^accounts/', include('registration.backends.default.urls'))

)

profile = Token.objects.get(user=request.user)
#set a new api key
profile.api_key =hashlib.sha1(str(random.random()) +
                                   'app_name' +
                                 str(time.time())).hexdigest()
profile.save()