def create_vote(inputs, reference_inputs, parameters, options, participants,
tally_priv, tally_pub):
# genrate param
params = setup()
pub = unpack(tally_pub)
# encrypt initial score
(a, b, k) = binencrypt(params, pub, 0) # encryption of a zero
c = (a, b)
scores = [pack(c) for _ in loads(options)]
# new vote object
new_vote = {
'type': 'VoteObject',
'options': loads(options),
'scores': scores,
'participants': loads(participants),
'tally_pub': tally_pub
}
# proof that all init values are zero
proof_init = provezero(params, pub, c, unpack(tally_priv))
# return
return {
'outputs': (inputs[0], dumps(new_vote)),
'extra_parameters': {
'proof_init': pack(proof_init)
}
}
def tally(inputs, reference_inputs, parameters, tally_priv, tally_pub):
# retrieve last vote
vote = loads(inputs[0])
# generate params & retrieve tally's public key
params = setup()
table = make_table(params)
(G, _, (h0, _, _, _), _) = params
# decrypt aggregated results
outcome = []
for item in vote['scores']:
outcome.append(dec(params, table, unpack(tally_priv), unpack(item)))
# proof of decryption
proof_dec = []
for i in range(0, len(vote['scores'])):
a, b = unpack(vote['scores'][i])
ciphertext = (a, b - outcome[i] * h0)
tmp = provezero(params, unpack(tally_pub), ciphertext,
unpack(tally_priv))
proof_dec.append(pack(tmp))
# signature
hasher = sha256()
hasher.update(dumps(vote).encode('utf8'))
hasher.update(dumps(outcome).encode('utf8'))
sig = do_ecdsa_sign(G, unpack(tally_priv), hasher.digest())
# pack result
result = {'type': 'VoteResult', 'outcome': outcome}
# return
return {
'outputs': (dumps(result), ),
'extra_parameters': {
'proof_dec': dumps(proof_dec),
'signature': pack(sig)
}
}