Check if combined public key was correcly computed

check_trustees.py

#!/usr/bin/env python3
import requests
import sys
import os
import re

election_uuid = sys.argv[1]

base_url = 'https://votacao.ufscar.br'
login_url = '{}/auth/ldap/login'.format(base_url)
election_url = '{}/helios/elections/{}'.format(base_url, election_uuid)

s = requests.session()
r = s.get(login_url)
r.raise_for_status()
m = re.search(r'<input type="hidden" name="csrf_token" value="(.*?)" />', r.text)
csrf_token = m.group(1)
r = s.post(login_url, {'csrf_token': csrf_token,
                       'username': os.getenv('HELIOS_USERNAME'),
                       'password': os.getenv('HELIOS_PASSWORD')})
r.raise_for_status()

r = s.get(election_url)
r.raise_for_status()
election = r.json()

r = s.get(election_url + '/trustees')
r.raise_for_status()
trustees = r.json()

pk = trustees[0]['public_key']
for trustee in trustees[1:]:
    pkt = trustee['public_key']
    assert pkt['p'] == pk['p']
    assert pkt['q'] == pk['q']
    assert pkt['g'] == pk['g']
    pk['y'] = str((int(pk['y']) * int(pkt['y'])) % int(pk['p']))

assert pk == election['public_key']
print(pk)