def test_get_plaintext_tally_all_guardians_present(self, data,
parties: int,
contests: int):
# Arrange
description = data.draw(election_descriptions(parties, contests))
builder = ElectionBuilder(self.NUMBER_OF_GUARDIANS, self.QUORUM,
description)
metadata, context = builder.set_public_key(
self.joint_public_key).build()
plaintext_ballots: List[PlaintextBallot] = data.draw(
plaintext_voted_ballots(metadata, randrange(3, 6)))
plaintext_tallies = accumulate_plaintext_ballots(plaintext_ballots)
encrypted_tally = self._generate_encrypted_tally(
metadata, context, plaintext_ballots)
subject = DecryptionMediator(metadata, context, encrypted_tally)
# act
for guardian in self.guardians:
self.assertIsNotNone(subject.announce(guardian))
decrypted_tallies = subject.get_plaintext_tally()
result = self._convert_to_selections(decrypted_tallies)
# assert
self.assertIsNotNone(result)
self.assertEqual(plaintext_tallies, result)
def test_get_plaintext_tally_with_all_guardians_present(
self, values, parties: int, contests: int):
# Arrange
description = values.draw(election_descriptions(parties, contests))
builder = ElectionBuilder(self.NUMBER_OF_GUARDIANS, self.QUORUM,
description)
internal_manifest, context = (builder.set_public_key(
self.joint_public_key.joint_public_key).set_commitment_hash(
self.joint_public_key.commitment_hash).build())
plaintext_ballots: List[PlaintextBallot] = values.draw(
plaintext_voted_ballots(internal_manifest, randrange(3, 6)))
expected_plaintext_tally = accumulate_plaintext_ballots(
plaintext_ballots)
encrypted_tally = self._generate_encrypted_tally(
internal_manifest, context, plaintext_ballots)
mediator = DecryptionMediator(self.decryption_mediator_id, context)
available_guardians = self.guardians
DecryptionHelper.perform_decryption_setup(available_guardians,
mediator, context,
encrypted_tally, [])
# Act
plaintext_tally = mediator.get_plaintext_tally(encrypted_tally)
selections = _convert_to_selections(plaintext_tally)
# Assert
self.assertIsNotNone(plaintext_tally)
self.assertIsNotNone(selections)
self.assertEqual(expected_plaintext_tally, selections)
def test_tally_cast_ballots_accumulates_valid_tally(
self, everything: ELECTIONS_AND_BALLOTS_TUPLE_TYPE):
# Arrange
(
_election_description,
internal_manifest,
ballots,
secret_key,
context,
) = everything
# Tally the plaintext ballots for comparison later
plaintext_tallies = accumulate_plaintext_ballots(ballots)
# encrypt each ballot
store = DataStore()
encryption_seed = ElectionFactory.get_encryption_device().get_hash()
for ballot in ballots:
encrypted_ballot = encrypt_ballot(ballot, internal_manifest,
context, encryption_seed)
encryption_seed = encrypted_ballot.code
self.assertIsNotNone(encrypted_ballot)
# add to the ballot store
store.set(
encrypted_ballot.object_id,
from_ciphertext_ballot(encrypted_ballot, BallotBoxState.CAST),
)
# act
result = tally_ballots(store, internal_manifest, context)
self.assertIsNotNone(result)
# Assert
decrypted_tallies = self._decrypt_with_secret(result, secret_key)
self.assertEqual(plaintext_tallies, decrypted_tallies)
def test_tally_spoiled_ballots_accumulates_valid_tally(
self, everything: ELECTIONS_AND_BALLOTS_TUPLE_TYPE):
# Arrange
metadata, ballots, secret_key, context = everything
# Tally the plaintext ballots for comparison later
plaintext_tallies = accumulate_plaintext_ballots(ballots)
# encrypt each ballot
store = BallotStore()
seed_hash = EncryptionDevice("Location").get_hash()
for ballot in ballots:
encrypted_ballot = encrypt_ballot(ballot, metadata, context,
seed_hash)
seed_hash = encrypted_ballot.tracking_hash
self.assertIsNotNone(encrypted_ballot)
# add to the ballot store
store.set(
encrypted_ballot.object_id,
from_ciphertext_ballot(encrypted_ballot,
BallotBoxState.SPOILED),
)
# act
result = tally_ballots(store, metadata, context)
self.assertIsNotNone(result)
# Assert
decrypted_tallies = self._decrypt_with_secret(result, secret_key)
self.assertCountEqual(plaintext_tallies, decrypted_tallies)
for value in decrypted_tallies.values():
self.assertEqual(0, value)
self.assertEqual(len(ballots), len(result.spoiled_ballots))
def setUp(self):
self.key_ceremony = KeyCeremonyMediator(self.CEREMONY_DETAILS)
self.guardians: List[Guardian] = []
# Setup Guardians
for i in range(self.NUMBER_OF_GUARDIANS):
sequence = i + 2
self.guardians.append(
Guardian(
"guardian_" + str(sequence),
sequence,
self.NUMBER_OF_GUARDIANS,
self.QUORUM,
))
# Attendance (Public Key Share)
for guardian in self.guardians:
self.key_ceremony.announce(guardian)
self.key_ceremony.orchestrate(identity_auxiliary_encrypt)
self.key_ceremony.verify(identity_auxiliary_decrypt)
self.joint_public_key = self.key_ceremony.publish_joint_key()
self.assertIsNotNone(self.joint_public_key)
# setup the election
self.election = election_factory.get_fake_election()
builder = ElectionBuilder(self.NUMBER_OF_GUARDIANS, self.QUORUM,
self.election)
self.assertIsNone(
builder.build()) # Can't build without the public key
builder.set_public_key(self.joint_public_key)
self.metadata, self.context = get_optional(builder.build())
self.encryption_device = EncryptionDevice("location")
self.ballot_marking_device = EncryptionMediator(
self.metadata, self.context, self.encryption_device)
# get some fake ballots
self.fake_cast_ballot = ballot_factory.get_fake_ballot(
self.metadata, "some-unique-ballot-id-cast")
self.more_fake_ballots = []
for i in range(10):
self.more_fake_ballots.append(
ballot_factory.get_fake_ballot(
self.metadata, f"some-unique-ballot-id-cast{i}"))
self.fake_spoiled_ballot = ballot_factory.get_fake_ballot(
self.metadata, "some-unique-ballot-id-spoiled")
self.assertTrue(
self.fake_cast_ballot.is_valid(
self.metadata.ballot_styles[0].object_id))
self.assertTrue(
self.fake_spoiled_ballot.is_valid(
self.metadata.ballot_styles[0].object_id))
self.expected_plaintext_tally = accumulate_plaintext_ballots(
[self.fake_cast_ballot] + self.more_fake_ballots)
# Fill in the expected values with any missing selections
# that were not made on any ballots
selection_ids = set([
selection.object_id for contest in self.metadata.contests
for selection in contest.ballot_selections
])
missing_selection_ids = selection_ids.difference(
set(self.expected_plaintext_tally))
for id in missing_selection_ids:
self.expected_plaintext_tally[id] = 0
# Encrypt
encrypted_fake_cast_ballot = self.ballot_marking_device.encrypt(
self.fake_cast_ballot)
encrypted_fake_spoiled_ballot = self.ballot_marking_device.encrypt(
self.fake_spoiled_ballot)
self.assertIsNotNone(encrypted_fake_cast_ballot)
self.assertIsNotNone(encrypted_fake_spoiled_ballot)
self.assertTrue(
encrypted_fake_cast_ballot.is_valid_encryption(
self.context.crypto_extended_base_hash, self.joint_public_key))
# encrypt some more fake ballots
self.more_fake_encrypted_ballots = []
for fake_ballot in self.more_fake_ballots:
self.more_fake_encrypted_ballots.append(
self.ballot_marking_device.encrypt(fake_ballot))
# configure the ballot box
ballot_store = BallotStore()
ballot_box = BallotBox(self.metadata, self.context, ballot_store)
ballot_box.cast(encrypted_fake_cast_ballot)
ballot_box.spoil(encrypted_fake_spoiled_ballot)
# Cast some more fake ballots
for fake_ballot in self.more_fake_encrypted_ballots:
ballot_box.cast(fake_ballot)
# generate encrypted tally
self.ciphertext_tally = tally_ballots(ballot_store, self.metadata,
self.context)
def setUp(self):
# Key Ceremony
self.key_ceremony_mediator = KeyCeremonyMediator(
"key_ceremony_mediator_mediator", self.CEREMONY_DETAILS)
self.guardians: List[Guardian] = KeyCeremonyHelper.create_guardians(
self.CEREMONY_DETAILS)
KeyCeremonyHelper.perform_full_ceremony(self.guardians,
self.key_ceremony_mediator)
self.joint_public_key = self.key_ceremony_mediator.publish_joint_key()
# Setup the election
manifest = election_factory.get_fake_manifest()
builder = ElectionBuilder(self.NUMBER_OF_GUARDIANS, self.QUORUM,
manifest)
builder.set_public_key(self.joint_public_key.joint_public_key)
builder.set_commitment_hash(self.joint_public_key.commitment_hash)
self.internal_manifest, self.context = get_optional(builder.build())
self.encryption_device = election_factory.get_encryption_device()
self.ballot_marking_device = EncryptionMediator(
self.internal_manifest, self.context, self.encryption_device)
# get some fake ballots
self.fake_cast_ballot = ballot_factory.get_fake_ballot(
self.internal_manifest, "some-unique-ballot-id-cast")
self.more_fake_ballots = []
for i in range(10):
self.more_fake_ballots.append(
ballot_factory.get_fake_ballot(
self.internal_manifest, f"some-unique-ballot-id-cast{i}"))
self.fake_spoiled_ballot = ballot_factory.get_fake_ballot(
self.internal_manifest, "some-unique-ballot-id-spoiled")
self.more_fake_spoiled_ballots = []
for i in range(2):
self.more_fake_spoiled_ballots.append(
ballot_factory.get_fake_ballot(
self.internal_manifest,
f"some-unique-ballot-id-spoiled{i}"))
self.assertTrue(
self.fake_cast_ballot.is_valid(
self.internal_manifest.ballot_styles[0].object_id))
self.assertTrue(
self.fake_spoiled_ballot.is_valid(
self.internal_manifest.ballot_styles[0].object_id))
self.expected_plaintext_tally = accumulate_plaintext_ballots(
[self.fake_cast_ballot] + self.more_fake_ballots)
# Fill in the expected values with any missing selections
# that were not made on any ballots
selection_ids = {
selection.object_id
for contest in self.internal_manifest.contests
for selection in contest.ballot_selections
}
missing_selection_ids = selection_ids.difference(
set(self.expected_plaintext_tally))
for id in missing_selection_ids:
self.expected_plaintext_tally[id] = 0
# Encrypt
self.encrypted_fake_cast_ballot = self.ballot_marking_device.encrypt(
self.fake_cast_ballot)
self.encrypted_fake_spoiled_ballot = self.ballot_marking_device.encrypt(
self.fake_spoiled_ballot)
# encrypt some more fake ballots
self.more_fake_encrypted_ballots = []
for fake_ballot in self.more_fake_ballots:
self.more_fake_encrypted_ballots.append(
self.ballot_marking_device.encrypt(fake_ballot))
# encrypt some more fake ballots
self.more_fake_encrypted_spoiled_ballots = []
for fake_ballot in self.more_fake_spoiled_ballots:
self.more_fake_encrypted_spoiled_ballots.append(
self.ballot_marking_device.encrypt(fake_ballot))
# configure the ballot box
ballot_store = DataStore()
ballot_box = BallotBox(self.internal_manifest, self.context,
ballot_store)
ballot_box.cast(self.encrypted_fake_cast_ballot)
ballot_box.spoil(self.encrypted_fake_spoiled_ballot)
# Cast some more fake ballots
for fake_ballot in self.more_fake_encrypted_ballots:
ballot_box.cast(fake_ballot)
# Spoil some more fake ballots
for fake_ballot in self.more_fake_encrypted_spoiled_ballots:
ballot_box.spoil(fake_ballot)
# generate encrypted tally
self.ciphertext_tally = tally_ballots(ballot_store,
self.internal_manifest,
self.context)
self.ciphertext_ballots = get_ballots(ballot_store,
BallotBoxState.SPOILED)
def test_accumulation_encryption_decryption(
self,
everything: ELECTIONS_AND_BALLOTS_TUPLE_TYPE,
nonce: ElementModQ,
):
"""
Tests that decryption is the inverse of encryption over arbitrarily generated elections and ballots.
This test uses an abitrarily generated dataset with a single public-private keypair for the election
encryption context. It also manually verifies that homomorphic accumulation works as expected.
"""
# Arrange
election_description, metadata, ballots, secret_key, context = everything
# Tally the plaintext ballots for comparison later
plaintext_tallies = accumulate_plaintext_ballots(ballots)
num_ballots = len(ballots)
num_contests = len(metadata.contests)
zero_nonce, *nonces = Nonces(nonce)[:num_ballots + 1]
self.assertEqual(len(nonces), num_ballots)
self.assertTrue(len(metadata.contests) > 0)
# Generatea valid encryption of zero
encrypted_zero = elgamal_encrypt(0, zero_nonce,
context.elgamal_public_key)
# Act
encrypted_ballots = []
# encrypt each ballot
for i in range(num_ballots):
encrypted_ballot = encrypt_ballot(ballots[i], metadata, context,
SEED_HASH, nonces[i])
encrypted_ballots.append(encrypted_ballot)
# sanity check the encryption
self.assertIsNotNone(encrypted_ballot)
self.assertEqual(num_contests, len(encrypted_ballot.contests))
# decrypt the ballot with secret and verify it matches the plaintext
decrypted_ballot = decrypt_ballot_with_secret(
ballot=encrypted_ballot,
election_metadata=metadata,
crypto_extended_base_hash=context.crypto_extended_base_hash,
public_key=context.elgamal_public_key,
secret_key=secret_key,
remove_placeholders=True,
)
self.assertEqual(ballots[i], decrypted_ballot)
# homomorphically accumualte the encrypted ballot representations
encrypted_tallies = _accumulate_encrypted_ballots(
encrypted_zero, encrypted_ballots)
decrypted_tallies = {}
for object_id in encrypted_tallies.keys():
decrypted_tallies[object_id] = encrypted_tallies[
object_id].decrypt(secret_key)
# loop through the contest descriptions and verify
# the decrypted tallies match the plaintext tallies
for contest in metadata.contests:
# Sanity check the generated data
self.assertTrue(len(contest.ballot_selections) > 0)
self.assertTrue(len(contest.placeholder_selections) > 0)
decrypted_selection_tallies = [
decrypted_tallies[selection.object_id]
for selection in contest.ballot_selections
]
decrypted_placeholder_tallies = [
decrypted_tallies[placeholder.object_id]
for placeholder in contest.placeholder_selections
]
plaintext_tally_values = [
plaintext_tallies[selection.object_id]
for selection in contest.ballot_selections
]
# verify the plaintext tallies match the decrypted tallies
self.assertEqual(decrypted_selection_tallies,
plaintext_tally_values)
# validate the right number of selections including placeholders across all ballots
self.assertEqual(
contest.number_elected * num_ballots,
sum(decrypted_selection_tallies) +
sum(decrypted_placeholder_tallies),
)
