def perform_round_2(guardians: List[Guardian],
mediator: KeyCeremonyMediator) -> None:
"""Perform Round 2 including generating backups and sharing backups"""
for guardian in guardians:
guardian.generate_election_partial_key_backups(
identity_auxiliary_encrypt)
mediator.receive_backups(
guardian.share_election_partial_key_backups())
for guardian in guardians:
backups = mediator.share_backups(guardian.id)
for backup in backups:
guardian.save_election_partial_key_backup(backup)
def test_exchange_of_backups(self):
"""Round 2: Exchange of election partial key backups"""
# Arrange
mediator = KeyCeremonyMediator("mediator_backups_exchange",
CEREMONY_DETAILS)
KeyCeremonyHelper.perform_round_1(GUARDIANS, mediator)
# Round 2 - Guardians Only
GUARDIAN_1.generate_election_partial_key_backups()
GUARDIAN_2.generate_election_partial_key_backups()
backup_from_1_for_2 = GUARDIAN_1.share_election_partial_key_backup(
GUARDIAN_2_ID)
backup_from_2_for_1 = GUARDIAN_2.share_election_partial_key_backup(
GUARDIAN_1_ID)
# Act
mediator.receive_backups([backup_from_1_for_2])
# Assert
self.assertFalse(mediator.all_backups_available())
# Act
mediator.receive_backups([backup_from_2_for_1])
# Assert
self.assertTrue(mediator.all_backups_available())
# Act
guardian1_backups = mediator.share_backups(GUARDIAN_1_ID)
guardian2_backups = mediator.share_backups(GUARDIAN_2_ID)
# Assert
self.assertIsNotNone(guardian1_backups)
self.assertIsNotNone(guardian2_backups)
self.assertEqual(len(guardian1_backups), 1)
self.assertEqual(len(guardian2_backups), 1)
for backup in guardian1_backups:
self.assertEqual(backup.designated_id, GUARDIAN_1_ID)
for backup in guardian2_backups:
self.assertEqual(backup.designated_id, GUARDIAN_2_ID)
self.assertEqual(guardian1_backups[0], backup_from_2_for_1)
self.assertEqual(guardian2_backups[0], backup_from_1_for_2)
class TestEndToEndElection(TestCase):
"""
Test a complete simple example of executing an End-to-End encrypted election.
In a real world scenario all of these steps would not be completed on the same machine.
"""
NUMBER_OF_GUARDIANS = 5
QUORUM = 3
REMOVE_OUTPUT = False
# Step 0 - Configure Election
manifest: Manifest
election_builder: ElectionBuilder
internal_manifest: InternalManifest
context: CiphertextElectionContext
constants: ElectionConstants
# Step 1 - Key Ceremony
mediator: KeyCeremonyMediator
guardians: List[Guardian] = []
# Step 2 - Encrypt Votes
device: EncryptionDevice
encrypter: EncryptionMediator
plaintext_ballots: List[PlaintextBallot]
ciphertext_ballots: List[CiphertextBallot] = []
# Step 3 - Cast and Spoil
ballot_store: DataStore
ballot_box: BallotBox
# Step 4 - Decrypt Tally
ciphertext_tally: CiphertextTally
plaintext_tally: PlaintextTally
plaintext_spoiled_ballots: Dict[str, PlaintextTally]
decryption_mediator: DecryptionMediator
# Step 5 - Publish
guardian_records: List[GuardianRecord] = []
def test_end_to_end_election(self) -> None:
"""
Execute the simplified end-to-end test demonstrating each component of the system.
"""
self.step_0_configure_election()
self.step_1_key_ceremony()
self.step_2_encrypt_votes()
self.step_3_cast_and_spoil()
self.step_4_decrypt_tally()
self.step_5_publish_and_verify()
def step_0_configure_election(self) -> None:
"""
To conduct an election, load an `Manifest` file
"""
# Load a pre-configured Election Description
# TODO: replace with complex election
self.manifest = ElectionFactory().get_simple_manifest_from_file()
print(f"""
{'-'*40}\n
# Election Summary:
# Scope: {self.manifest.election_scope_id}
# Geopolitical Units: {len(self.manifest.geopolitical_units)}
# Parties: {len(self.manifest.parties)}
# Candidates: {len(self.manifest.candidates)}
# Contests: {len(self.manifest.contests)}
# Ballot Styles: {len(self.manifest.ballot_styles)}\n
{'-'*40}\n
""")
self._assert_message(
Manifest.is_valid.__qualname__,
"Verify that the input election meta-data is well-formed",
self.manifest.is_valid(),
)
# Create an Election Builder
self.election_builder = ElectionBuilder(self.NUMBER_OF_GUARDIANS,
self.QUORUM, self.manifest)
self._assert_message(
ElectionBuilder.__qualname__,
f"Created with number_of_guardians: {self.NUMBER_OF_GUARDIANS} quorum: {self.QUORUM}",
)
# Move on to the Key Ceremony
def step_1_key_ceremony(self) -> None:
"""
Using the NUMBER_OF_GUARDIANS, generate public-private keypairs and share
representations of those keys with QUORUM of other Guardians. Then, combine
the public election keys to make a joint election key that is used to encrypt ballots
"""
# Setup Guardians
for i in range(self.NUMBER_OF_GUARDIANS):
self.guardians.append(
Guardian(
"guardian_" + str(i + 1),
i + 1,
self.NUMBER_OF_GUARDIANS,
self.QUORUM,
))
# Setup Mediator
self.mediator = KeyCeremonyMediator("mediator_1",
self.guardians[0].ceremony_details)
# ROUND 1: Public Key Sharing
# Announce
for guardian in self.guardians:
self.mediator.announce(guardian.share_public_keys())
# Share Keys
for guardian in self.guardians:
announced_keys = self.mediator.share_announced()
for key_set in announced_keys:
if guardian.id is not key_set.election.owner_id:
guardian.save_guardian_public_keys(key_set)
self._assert_message(
KeyCeremonyMediator.all_guardians_announced.__qualname__,
"Confirms all guardians have shared their public keys",
self.mediator.all_guardians_announced(),
)
# ROUND 2: Election Partial Key Backup Sharing
# Share Backups
for sending_guardian in self.guardians:
sending_guardian.generate_election_partial_key_backups(
identity_auxiliary_encrypt)
backups = []
for designated_guardian in self.guardians:
if designated_guardian.id != sending_guardian.id:
backups.append(
sending_guardian.share_election_partial_key_backup(
designated_guardian.id))
self.mediator.receive_backups(backups)
self._assert_message(
KeyCeremonyMediator.receive_backups.__qualname__,
"Receive election partial key backups from key owning guardian",
len(backups) == NUMBER_OF_GUARDIANS - 1,
)
self._assert_message(
KeyCeremonyMediator.all_backups_available.__qualname__,
"Confirm all guardians have shared their election partial key backups",
self.mediator.all_backups_available(),
)
# Receive Backups
for designated_guardian in self.guardians:
backups = self.mediator.share_backups(designated_guardian.id)
self._assert_message(
KeyCeremonyMediator.share_backups.__qualname__,
"Share election partial key backups for the designated guardian",
len(backups) == NUMBER_OF_GUARDIANS - 1,
)
for backup in backups:
designated_guardian.save_election_partial_key_backup(backup)
# ROUND 3: Verification of Backups
# Verify Backups
for designated_guardian in self.guardians:
verifications = []
for backup_owner in self.guardians:
if designated_guardian.id is not backup_owner.id:
verification = (
designated_guardian.verify_election_partial_key_backup(
backup_owner.id, identity_auxiliary_encrypt))
verifications.append(verification)
self.mediator.receive_backup_verifications(verifications)
self._assert_message(
KeyCeremonyMediator.all_backups_verified.__qualname__,
"Confirms all guardians have verified the backups of all other guardians",
self.mediator.all_backups_verified(),
)
# FINAL: Publish Joint Key
joint_key = self.mediator.publish_joint_key()
self._assert_message(
KeyCeremonyMediator.publish_joint_key.__qualname__,
"Publishes the Joint Election Key",
joint_key is not None,
)
# Build the Election
self.election_builder.set_public_key(
get_optional(joint_key).joint_public_key)
self.election_builder.set_commitment_hash(
get_optional(joint_key).commitment_hash)
self.internal_manifest, self.context = get_optional(
self.election_builder.build())
self.constants = ElectionConstants()
# Move on to encrypting ballots
def step_2_encrypt_votes(self) -> None:
"""
Using the `CiphertextElectionContext` encrypt ballots for the election
"""
# Configure the Encryption Device
self.device = ElectionFactory.get_encryption_device()
self.encrypter = EncryptionMediator(self.internal_manifest,
self.context, self.device)
self._assert_message(
EncryptionDevice.__qualname__,
f"Ready to encrypt at location: {self.device.location}",
)
# Load some Ballots
self.plaintext_ballots = BallotFactory().get_simple_ballots_from_file()
self._assert_message(
PlaintextBallot.__qualname__,
f"Loaded ballots: {len(self.plaintext_ballots)}",
len(self.plaintext_ballots) > 0,
)
# Encrypt the Ballots
for plaintext_ballot in self.plaintext_ballots:
encrypted_ballot = self.encrypter.encrypt(plaintext_ballot)
self._assert_message(
EncryptionMediator.encrypt.__qualname__,
f"Ballot Id: {plaintext_ballot.object_id}",
encrypted_ballot is not None,
)
self.ciphertext_ballots.append(get_optional(encrypted_ballot))
# Next, we cast or spoil the ballots
def step_3_cast_and_spoil(self) -> None:
"""
Accept each ballot by marking it as either cast or spoiled.
This example demonstrates one way to accept ballots using the `BallotBox` class
"""
# Configure the Ballot Box
self.ballot_store = DataStore()
self.ballot_box = BallotBox(self.internal_manifest, self.context,
self.ballot_store)
# Randomly cast or spoil the ballots
for ballot in self.ciphertext_ballots:
if randint(0, 1):
submitted_ballot = self.ballot_box.cast(ballot)
else:
submitted_ballot = self.ballot_box.spoil(ballot)
self._assert_message(
BallotBox.__qualname__,
f"Submitted Ballot Id: {ballot.object_id} state: {get_optional(submitted_ballot).state}",
submitted_ballot is not None,
)
def step_4_decrypt_tally(self) -> None:
"""
Homomorphically combine the selections made on all of the cast ballots
and use the Available Guardians to decrypt the combined tally.
In this way, no individual voter's cast ballot is ever decrypted drectly.
"""
# Generate a Homomorphically Accumulated Tally of the ballots
self.ciphertext_tally = get_optional(
tally_ballots(self.ballot_store, self.internal_manifest,
self.context))
self.ciphertext_ballots = get_ballots(self.ballot_store,
BallotBoxState.SPOILED)
self._assert_message(
tally_ballots.__qualname__,
f"""
- cast: {self.ciphertext_tally.cast()}
- spoiled: {self.ciphertext_tally.spoiled()}
Total: {len(self.ciphertext_tally)}
""",
self.ciphertext_tally is not None,
)
# Configure the Decryption
ciphertext_ballots = list(self.ciphertext_ballots.values())
self.decryption_mediator = DecryptionMediator(
"decryption-mediator",
self.context,
)
# Announce each guardian as present
count = 0
for guardian in self.guardians:
guardian_key = guardian.share_election_public_key()
tally_share = guardian.compute_tally_share(self.ciphertext_tally,
self.context)
ballot_shares = guardian.compute_ballot_shares(
ciphertext_ballots, self.context)
self.decryption_mediator.announce(guardian_key, tally_share,
ballot_shares)
count += 1
self._assert_message(
DecryptionMediator.announce.__qualname__,
f"Guardian Present: {guardian.id}",
len(self.decryption_mediator.get_available_guardians()) ==
count,
)
# Get the plaintext Tally
self.plaintext_tally = get_optional(
self.decryption_mediator.get_plaintext_tally(
self.ciphertext_tally))
self._assert_message(
DecryptionMediator.get_plaintext_tally.__qualname__,
"Tally Decrypted",
self.plaintext_tally is not None,
)
# Get the plaintext Spoiled Ballots
self.plaintext_spoiled_ballots = get_optional(
self.decryption_mediator.get_plaintext_ballots(ciphertext_ballots))
self._assert_message(
DecryptionMediator.get_plaintext_ballots.__qualname__,
"Spoiled Ballots Decrypted",
self.plaintext_tally is not None,
)
# Now, compare the results
self.compare_results()
def compare_results(self) -> None:
"""
Compare the results to ensure the decryption was done correctly
"""
print(f"""
{'-'*40}
# Election Results:
""")
# Create a representation of each contest's tally
selection_ids = [
selection.object_id for contest in self.manifest.contests
for selection in contest.ballot_selections
]
expected_plaintext_tally: Dict[str, int] = {
key: 0
for key in selection_ids
}
# Tally the expected values from the loaded ballots
for ballot in self.plaintext_ballots:
if (get_optional(self.ballot_store.get(
ballot.object_id)).state == BallotBoxState.CAST):
for contest in ballot.contests:
for selection in contest.ballot_selections:
expected_plaintext_tally[
selection.object_id] += selection.vote
# Compare the expected tally to the decrypted tally
for tally_contest in self.plaintext_tally.contests.values():
print(f" Contest: {tally_contest.object_id}")
for tally_selection in tally_contest.selections.values():
expected = expected_plaintext_tally[tally_selection.object_id]
self._assert_message(
f" - Selection: {tally_selection.object_id}",
f"expected: {expected}, actual: {tally_selection.tally}",
expected == tally_selection.tally,
)
print(f"\n{'-'*40}\n")
# Compare the expected values for each spoiled ballot
for ballot in self.plaintext_ballots:
if (get_optional(self.ballot_store.get(
ballot.object_id)).state == BallotBoxState.SPOILED):
print(f"\nSpoiled Ballot: {ballot.object_id}")
for contest in ballot.contests:
print(f"\n Contest: {contest.object_id}")
for selection in contest.ballot_selections:
expected = selection.vote
decrypted_selection = (self.plaintext_spoiled_ballots[
ballot.object_id].contests[contest.object_id].
selections[selection.object_id])
self._assert_message(
f" - Selection: {selection.object_id}",
f"expected: {expected}, actual: {decrypted_selection.tally}",
expected == decrypted_selection.tally,
)
def step_5_publish_and_verify(self) -> None:
"""Publish and verify steps of the election"""
self.publish_results()
self.verify_results()
if self.REMOVE_OUTPUT:
rmtree(RESULTS_DIR)
def publish_results(self) -> None:
"""
Publish results/artifacts of the election
"""
self.guardian_records = [
guardian.publish() for guardian in self.guardians
]
publish(
self.manifest,
self.context,
self.constants,
[self.device],
self.ballot_store.all(),
self.plaintext_spoiled_ballots.values(),
self.ciphertext_tally.publish(),
self.plaintext_tally,
self.guardian_records,
RESULTS_DIR,
)
self._assert_message(
"Publish",
f"Artifacts published to: {RESULTS_DIR}",
path.exists(RESULTS_DIR),
)
def verify_results(self) -> None:
"""Verify results of election"""
# Deserialize
manifest_from_file = Manifest.from_json_file(MANIFEST_FILE_NAME,
RESULTS_DIR)
self.assertEqual(self.manifest, manifest_from_file)
context_from_file = CiphertextElectionContext.from_json_file(
CONTEXT_FILE_NAME, RESULTS_DIR)
self.assertEqual(self.context, context_from_file)
constants_from_file = ElectionConstants.from_json_file(
CONSTANTS_FILE_NAME, RESULTS_DIR)
self.assertEqual(self.constants, constants_from_file)
device_name = DEVICE_PREFIX + str(self.device.uuid)
device_from_file = EncryptionDevice.from_json_file(
device_name, DEVICES_DIR)
self.assertEqual(self.device, device_from_file)
for ballot in self.ballot_store.all():
name = BALLOT_PREFIX + ballot.object_id
ballot_from_file = SubmittedBallot.from_json_file(
name, BALLOTS_DIR)
self.assertEqual(ballot, ballot_from_file)
for spoiled_ballot in self.plaintext_spoiled_ballots.values():
name = BALLOT_PREFIX + spoiled_ballot.object_id
spoiled_ballot_from_file = PlaintextTally.from_json_file(
name, SPOILED_DIR)
self.assertEqual(spoiled_ballot, spoiled_ballot_from_file)
published_ciphertext_tally_from_file = PublishedCiphertextTally.from_json_file(
ENCRYPTED_TALLY_FILE_NAME, RESULTS_DIR)
self.assertEqual(self.ciphertext_tally.publish(),
published_ciphertext_tally_from_file)
plainttext_tally_from_file = PlaintextTally.from_json_file(
TALLY_FILE_NAME, RESULTS_DIR)
self.assertEqual(self.plaintext_tally, plainttext_tally_from_file)
for guardian_record in self.guardian_records:
set_name = COEFFICIENT_PREFIX + guardian_record.guardian_id
guardian_record_from_file = GuardianRecord.from_json_file(
set_name, GUARDIAN_DIR)
self.assertEqual(guardian_record, guardian_record_from_file)
def _assert_message(self,
name: str,
message: str,
condition: Union[Callable, bool] = True) -> None:
if callable(condition):
result = condition()
else:
result = condition
print(f"{name}: {message}: {result}")
self.assertTrue(result)