name 'privtopub' is not defined

My code looks like:

from django.shortcuts import render, redirect
from django.contrib.auth.models import User, auth
from django.contrib import messages
from .models import Details
from bitcoin import *
import random
import bs4
import requests

def login(request):

    if request.method == 'POST':
        username = request.POST['username']
        password = request.POST['password']

        user = auth.authenticate(username=username, password=password)

        if user is not None:
            auth.login(request, user)
            return redirect('/')
        else:
            messages.info(request, 'Invalid Credentials')
            return redirect('login')

    else:
        return render(request, 'login.htm')

def register(request):

    detail = Details()
    bits = random.getrandbits(256)
    bits_hex = hex(bits)
    private_key = bits_hex[2:]
    print(private_key)
    # private_key = random_key()
    public_key = privtopub(private_key)
    address = pubtoaddr(public_key)
    detail.private_key = private_key
    detail.public_key = public_key
    detail.address = address

But I get the error: name 'privtopub' is not defined