94 lines
3.6 KiB
Python
94 lines
3.6 KiB
Python
# Eos - Verifiable elections
|
|
# Copyright © 2017 RunasSudo (Yingtong Li)
|
|
#
|
|
# This program is free software: you can redistribute it and/or modify
|
|
# it under the terms of the GNU Affero General Public License as published by
|
|
# the Free Software Foundation, either version 3 of the License, or
|
|
# (at your option) any later version.
|
|
#
|
|
# This program is distributed in the hope that it will be useful,
|
|
# but WITHOUT ANY WARRANTY; without even the implied warranty of
|
|
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
|
|
# GNU Affero General Public License for more details.
|
|
#
|
|
# You should have received a copy of the GNU Affero General Public License
|
|
# along with this program. If not, see <http://www.gnu.org/licenses/>.
|
|
|
|
from eos.core.bigint import *
|
|
from eos.core.objects import *
|
|
from eos.core.hashing import *
|
|
from eos.psr.election import *
|
|
|
|
class RPCMixnetParam(EmbeddedObject):
|
|
permutation = IntField()
|
|
reencryption = EmbeddedObjectListField(BigInt)
|
|
rand_a = EmbeddedObjectField(BigInt)
|
|
rand_b = EmbeddedObjectField(BigInt)
|
|
|
|
class RPCMixnet(EmbeddedObject):
|
|
mix_order = IntField()
|
|
params = EmbeddedObjectListField(RPCMixnetParam)
|
|
|
|
@property
|
|
def is_left(self):
|
|
return (self.mix_order % 2 == 0)
|
|
|
|
def random_permutation(self, n):
|
|
permutation = list(range(n))
|
|
# Fisher-Yates shuffle
|
|
i = n
|
|
while i != 0:
|
|
rnd = BigInt.crypto_random(0, i - 1)
|
|
rnd = rnd.__int__()
|
|
i -= 1
|
|
permutation[rnd], permutation[i] = permutation[i], permutation[rnd]
|
|
return permutation
|
|
|
|
def shuffle(self, encrypted_answers):
|
|
shuffled_answers = [None] * len(encrypted_answers)
|
|
permutations = self.random_permutation(len(encrypted_answers))
|
|
|
|
permutations_and_reenc = []
|
|
|
|
for i in range(len(encrypted_answers)):
|
|
encrypted_answer = encrypted_answers[i]
|
|
|
|
# Reencrypt the answer
|
|
shuffled_blocks = []
|
|
block_reencryptions = []
|
|
for block in encrypted_answer.blocks:
|
|
block2, reenc = block.reencrypt()
|
|
shuffled_blocks.append(block2)
|
|
block_reencryptions.append(reenc)
|
|
# And shuffle it to the new position
|
|
shuffled_answers[permutations[i]] = BlockEncryptedAnswer(blocks=shuffled_blocks)
|
|
# Record the parameters
|
|
permutations_and_reenc.append(RPCMixnetParam(permutation=permutations[i], reencryption=block_reencryptions, rand_a=block.public_key.group.random_Zq_element(), rand_b=block.public_key.group.random_Zq_element()))
|
|
|
|
commitments = []
|
|
if self.is_left:
|
|
for i in range(len(permutations_and_reenc)):
|
|
val = permutations_and_reenc[i]
|
|
val_obj = MixChallengeResponse(challenge_index=i, response_index=val.permutation, reenc=val.reencryption, rand=val.rand_a)
|
|
commitments.append(SHA256().update_obj(val_obj).hash_as_bigint())
|
|
else:
|
|
for i in range(len(permutations_and_reenc)):
|
|
# Find the answer that went to 'i'
|
|
idx = next(idx for idx in range(len(permutations_and_reenc)) if permutations_and_reenc[idx].permutation == i)
|
|
val = permutations_and_reenc[idx]
|
|
|
|
val_obj = MixChallengeResponse(challenge_index=i, response_index=idx, reenc=val.reencryption, rand=val.rand_b)
|
|
commitments.append(SHA256().update_obj(val_obj).hash_as_bigint())
|
|
|
|
self.params = permutations_and_reenc
|
|
return shuffled_answers, commitments
|
|
|
|
def challenge(self, i):
|
|
if self.is_left:
|
|
val = self.params[i]
|
|
return MixChallengeResponse(challenge_index=i, response_index=val.permutation, reenc=val.reencryption, rand=val.rand_a)
|
|
else:
|
|
idx = next(idx for idx in range(len(self.params)) if self.params[idx].permutation == i)
|
|
val = self.params[idx]
|
|
return MixChallengeResponse(challenge_index=i, response_index=idx, reenc=val.reencryption, rand=val.rand_b)
|