def create_petition_checker(inputs, reference_inputs, parameters, outputs,
returns, dependencies):
try:
# retrieve petition
petition = loads(outputs[1])
num_options = len(petition['options'])
print "CHECKING (create) - check format"
if len(inputs) != 1 or len(reference_inputs) != 0 or len(
outputs) != 2 or len(returns) != 0:
return False
if num_options < 1 or num_options != len(petition['scores']):
return False
print "CHECKING (create) - check tokens"
if loads(inputs[0])['type'] != 'PetitionEncToken' or loads(
outputs[0])['type'] != 'PetitionEncToken':
return False
if petition['type'] != 'PetitionEncObject':
return False
print "CHECKING (create) - check proof"
params = setup()
proof_init = unpack(parameters[0])
tally_pub = unpack(petition['tally_pub'])
for value in petition['scores']:
if not verifyzero(params, tally_pub, unpack(value), proof_init):
return False
# otherwise
return True
except (KeyError, Exception):
return False
def tally_checker(inputs, reference_inputs, parameters, outputs, returns,
dependencies):
try:
# retrieve vote
vote = loads(inputs[0])
result = loads(outputs[0])
# check format
if len(inputs) != 1 or len(reference_inputs) != 0 or len(
outputs) != 1 or len(returns) != 0:
return False
if len(vote['options']) != len(result['outcome']):
return False
# check tokens
if result['type'] != 'VoteResult':
return False
# generate params, retrieve tally's public key and the parameters
params = setup()
(G, _, (h0, _, _, _), _) = params
tally_pub = unpack(vote['tally_pub'])
sig = unpack(parameters['signature'])
proof_dec = loads(parameters['proof_dec'])
outcome = result['outcome']
# verify proof of correct decryption
for i in range(0, len(vote['scores'])):
a, b = unpack(vote['scores'][i])
ciphertext = (a, b - outcome[i] * h0)
if not verifyzero(params, tally_pub, ciphertext,
unpack(proof_dec[i])):
return False
# verify signature
hasher = sha256()
hasher.update(dumps(vote).encode('utf8'))
hasher.update(dumps(result['outcome']).encode('utf8'))
if not do_ecdsa_verify(G, tally_pub, sig, hasher.digest()):
return False
# otherwise
return True
except (KeyError, Exception):
return False
def create_vote_checker(inputs, reference_inputs, parameters, outputs, returns,
dependencies):
try:
# retrieve vote
vote = loads(outputs[1])
num_votes = len(vote['options'])
# check format
if len(inputs) != 1 or len(reference_inputs) != 0 or len(
outputs) != 2 or len(returns) != 0:
return False
if num_votes < 1 or num_votes != len(vote['scores']):
return False
if vote['participants'] == None:
return False
# check tokens
if loads(inputs[0])['type'] != 'VoteToken' or loads(
outputs[0])['type'] != 'VoteToken':
return False
if vote['type'] != 'VoteObject':
return False
# check proof
params = setup()
proof_init = unpack(parameters['proof_init'])
tally_pub = unpack(vote['tally_pub'])
for value in vote['scores']:
if not verifyzero(params, tally_pub, unpack(value), proof_init):
return False
# otherwise
return True
except (KeyError, Exception):
return False